Your tests. Your depth of insight.

A CBC is a starting point when investigating fatigue, anemia, infection, or changes during treatment. Hemoglobin reflects oxygen-carrying capacity; hematocrit is the proportion of blood occupied by red cells.

Red-cell size (MCV) helps classify anemia: small cells can suggest iron deficiency, while large cells can suggest B12 or folate deficiency, among other causes. Platelet and white-cell counts answer different questions.

This version reports total white cells, not their detailed breakdown. A normal hemoglobin does not exclude early iron deficiency; ferritin assesses iron stores. An abnormal count does not identify the cause by itself.

Sample: Whole blood · Fasting: not listed as required

Reference reviewed: 2026-10-26

• MedlinePlus — Complete blood count ↗
• MedlinePlus — CBC blood test ↗
• BC Guidelines — Iron deficiency ↗

A CMP brings together 14 measurements: glucose; sodium, potassium, chloride and bicarbonate; calcium; creatinine and urea nitrogen; albumin and total protein; and several liver-related markers. It is useful when a broad chemistry assessment is needed.

Patterns matter more than a single flag. Creatinine helps assess kidney filtration; ALT and AST mainly signal cell injury, while bilirubin and alkaline phosphatase help assess other liver or bile-duct patterns.

This is not a complete check of every organ. It does not include a CBC, thyroid tests, magnesium, or cholesterol. Meals, hydration, medicines, and sample handling can influence individual results.

Sample: Serum · Fasting: not listed as required

Reference reviewed: 2026-10-26

• MedlinePlus — Comprehensive metabolic panel ↗
• MedlinePlus — Liver function tests ↗

This panel separates three questions: how much iron is circulating, how much the blood can carry (TIBC), and how much is stored (ferritin). Transferrin saturation relates circulating iron to carrying capacity.

Low ferritin supports depleted iron stores, even before anemia develops. Low iron with high TIBC often fits iron deficiency. Low iron with normal or low TIBC may occur with inflammation. High transferrin saturation can prompt investigation for iron overload.

Ferritin also rises with inflammation and liver disease, so a high value does not automatically mean excess iron. Serum iron varies with recent intake and timing; interpret the panel with CBC and clinical context.

Sample: Serum · Fasting: yes, confirm instructions

Reference reviewed: 2026-10-26

• MedlinePlus — Iron tests ↗
• BC Guidelines — Iron deficiency ↗
• American Society of Hematology — 2026 iron deficiency guidance ↗
• BC Guidelines - iron overload ↗

The standard starting point for assessing cholesterol and monitoring lipid-lowering treatment. It reports total cholesterol, HDL-C and triglycerides, with LDL-C usually calculated. Non-HDL-C is total cholesterol minus HDL-C and captures cholesterol carried by all the main plaque-forming particles.

LDL-C measures cholesterol content, while ApoB reflects particle number. Non-HDL-C or ApoB can be especially informative when triglycerides are elevated. Treatment decisions use overall cardiovascular risk, not total cholesterol alone; lower LDL-C goals apply to people at higher risk.

A reassuring HDL-C does not cancel the risk from elevated LDL-C or ApoB. Very high triglycerides can affect calculated LDL-C accuracy and may require a fasting repeat or another measure. Follow the collection instructions for your actual panel. This standard panel does not include separate ApoB or Lp(a) measurements.

Sample: Serum · Fasting: yes, confirm instructions

Reference reviewed: 2026-10-26

• MedlinePlus · Cholesterol tests ↗
• CCS · Canadian lipid guideline pocket guide (2022) ↗
• AHA/ACC · Dyslipidemia guideline (2026) ↗

ApoB adds a particle-based view of cardiovascular risk. Each LDL, IDL, VLDL and Lp(a) particle carries one ApoB molecule. Measuring ApoB protein therefore estimates the number of these potentially plaque-forming particles—not their size or the amount of cholesterol inside them.

Two people can have the same LDL-C but different numbers of particles. When LDL-C and ApoB disagree (discordance), risk generally follows ApoB more closely. This is particularly useful with high triglycerides, diabetes or insulin resistance, and sometimes during lipid-lowering treatment. Canadian guidance prefers ApoB or non-HDL-C over LDL-C when triglycerides exceed 1.5 mmol/L.

This is an established test with a growing guideline role, not a direct count of LDL alone. It complements the lipid panel and does not replace a separate Lp(a) test. ApoB goals depend on overall risk; a laboratory “normal” range is not a personal treatment goal. For unit comparison, 1.0 g/L equals 100 mg/dL.

Sample: Serum · Fasting: not listed as required

Reference reviewed: 2026-10-26

• NLA · ApoB clinical consensus (2024) ↗
• CCS · Canadian lipid guideline pocket guide (2022) ↗
• AHA/ACC · Dyslipidemia guideline (2026) ↗

Lp(a) is an LDL-like particle with an additional protein, apo(a). Its level is largely inherited and can reveal cardiovascular risk missed by a routine lipid panel. It is also associated with calcification and narrowing of the aortic valve. Canadian and current US guidance support measurement at least once in adulthood.

Risk rises progressively, rather than switching on at one cutoff. The 2024 NLA framework identifies increased risk at ≥125 nmol/L or ≥50 mg/dL; Canadian guidance uses ≥100 nmol/L or ≥50 mg/dL. These are guideline cutoffs, not interchangeable unit conversions. A high result can support closer management of other risk factors and testing of first-degree relatives.

Do not convert mg/dL to nmol/L using a fixed multiplier: particle size varies. Levels are usually fairly stable, so frequent routine repeats add little, although illness and certain kidney, liver or thyroid conditions can affect results. A high Lp(a) does not diagnose a blocked artery, and a low ApoB does not exclude high Lp(a).

Sample: Serum · Fasting: not listed as required

Reference reviewed: 2026-10-26

• NLA · Lp(a) clinical update (2024) ↗
• ACC · Lp(a), units and guideline comparisons (2023) ↗
• AHA/ACC · Dyslipidemia guideline (2026) ↗

A1c measures the proportion of hemoglobin with glucose attached. It summarizes roughly 2–3 months of blood sugar exposure, with greater influence from recent weeks, and is useful for diabetes diagnosis and follow-up.

In appropriate nonpregnant adults, A1c of 6.5% or higher meets a diagnostic threshold for diabetes; without clear symptoms, confirmation is required. This diagnostic threshold is different from an individualized treatment target. Diabetes Canada defines A1c 6.0-6.4% as prediabetes; US guidance starts at 5.7%. These clinical definitions differ from a laboratory reference interval.

No fasting is needed for A1c itself. Blood loss, transfusion, altered red-cell survival, iron deficiency, and some hemoglobin variants can distort results. A1c may miss glucose swings and should be checked against glucose results when they disagree.

Sample: Whole blood · Fasting: not listed as required

Reference reviewed: 2026-10-26

• Diabetes Canada - diagnosis and definitions ↗
• NIDDK — The A1C test and diabetes ↗
• NIDDK — Diabetes and prediabetes tests ↗
• HealthLink BC — Diabetes diagnostic criteria ↗

Insulin helps glucose enter cells. Measuring it can be useful when investigating low blood sugar or, in selected cases, understanding insulin production. The result must be interpreted with a glucose value taken at the same time.

A high insulin level with normal or high glucose can reflect compensation for reduced insulin sensitivity. A result that is inappropriately high during low glucose raises a different question. C-peptide can help distinguish the body’s insulin production from injected insulin.

Insulin alone does not diagnose diabetes. Meals, fasting duration, medicines, and assay differences matter. There is no single universal fasting-insulin or HOMA-IR cutoff that diagnoses insulin resistance in everyone.

Sample: Serum · Fasting: yes, confirm instructions

Reference reviewed: 2026-10-26

• MedlinePlus — Insulin in blood ↗
• NIDDK — Insulin resistance and prediabetes ↗
• Endotext — Assessing insulin sensitivity and resistance ↗

Homocysteine is produced during amino-acid metabolism and is processed using folate, B12, and B6. It can help investigate suspected vitamin deficiency and, in specialized care, inherited disorders such as homocystinuria.

An elevated result is not specific to a vitamin deficiency: kidney disease, hypothyroidism, age, and smoking can also increase it. B12, folate, and sometimes methylmalonic acid help clarify the pattern.

Although higher levels are associated with vascular risk, lowering the number with vitamins has not reliably prevented heart attacks. It is not a routine cardiovascular screening test for everyone, and a lower number is not automatically a treatment goal.

Sample: Serum · Fasting: not listed as required

Reference reviewed: 2026-10-26

• MedlinePlus — Homocysteine ↗
• MedlinePlus — Methylmalonic acid ↗

Total 25-hydroxyvitamin D is the usual blood test for vitamin D status. It helps investigate bone or mineral problems, poor absorption, or suspected deficiency or toxicity. It differs from active 1,25-dihydroxyvitamin D, which answers other clinical questions.

Read the result with calcium, kidney function, supplements, and the reason for testing. Units matter: 1 ng/mL equals 2.5 nmol/L. Different assays and seasons can produce different results.

The Endocrine Society recommends against routine screening in otherwise healthy people without an established indication. Its 2024 prevention guideline does not define a universal blood level to target for disease prevention.

Sample: Serum · Fasting: not listed as required

Reference reviewed: 2026-10-26

• NIH Office of Dietary Supplements — Vitamin D ↗
• Endocrine Society — Vitamin D guideline (2024) ↗

High-sensitivity CRP measures the same inflammatory protein as standard CRP, but detects much smaller concentrations. Its distinctive role is refining cardiovascular risk and identifying residual inflammatory risk, even when cholesterol is controlled. It does not measure plaque directly.

A persistently elevated hs-CRP of ≥2 mg/L can be a cardiovascular risk-enhancing factor in clinical assessment. The meaningful value is a stable baseline when you are well—not a measurement during an infection. A repeat can help distinguish persistent inflammation from a temporary rise.

Infection, injury and inflammatory diseases can all increase CRP. A result above 10 mg/L warrants consideration of these causes rather than automatic interpretation as heart risk; reassess after recovery. hs-CRP cannot identify the site or cause of inflammation and is not interchangeable with a standard CRP assay for low-level cardiovascular assessment.

Sample: Serum · Fasting: not listed as required

Reference reviewed: 2026-10-26

• ACC · hs-CRP and cardiovascular risk (2025) ↗
• Quest · hs-CRP test guide ↗

GGT is especially useful alongside alkaline phosphatase (ALP). ALP can come from the liver or bone; an accompanying rise in GGT supports a liver or bile-duct source rather than a bone source.

GGT can rise with bile-duct problems, liver disease, alcohol exposure, and some medicines. It adds context to ALT, AST, ALP, and bilirubin rather than replacing them.

An isolated increase is nonspecific: it does not establish alcohol misuse, identify the cause, or directly measure liver function. Review medicines, supplements, alcohol intake, and other liver results before drawing conclusions.

Sample: Serum · Fasting: not listed as required

Reference reviewed: 2026-10-26

• MedlinePlus — GGT ↗
• MedlinePlus — Liver function tests ↗

Uric acid forms when the body breaks down purines. This test helps investigate gout and monitor urate-lowering treatment; kidney function and some medicines influence how efficiently urate is removed.

For people receiving gout treatment, a commonly used target is below 360 µmol/L (6 mg/dL); lower targets may be chosen in severe disease. This is a treatment target, not the laboratory’s usual reference interval.

High urate alone does not diagnose gout or mean treatment is needed. Urate can fall during an acute flare; if gout remains suspected, repeat testing after the flare can be useful.

Sample: Serum · Fasting: not listed as required

Reference reviewed: 2026-10-26

• MedlinePlus — Uric acid ↗
• NICE NG219 — Gout diagnosis and management ↗

B12 and folate support DNA production and red blood cell formation; B12 also supports nerves. Testing is useful with enlarged red cells, unexplained anemia, neurologic symptoms, poor absorption, or dietary and medication-related risks.

A borderline B12 result may be clarified with methylmalonic acid (MMA), interpreted with kidney function. B12-related nerve damage can occur without anemia. Serum folate is sensitive to recent food intake, so it is less informative about long-term stores.

Supplements can change blood results. Folate can improve the anemia of B12 deficiency without correcting its nerve effects, so an unexplained anemia should not be treated as folate deficiency alone without considering B12.

Sample: Serum · Fasting: not listed as required

Reference reviewed: 2026-10-26

• NIH Office of Dietary Supplements — Vitamin B12 ↗
• NIH Office of Dietary Supplements — Folate ↗

MMA is a functional clue to vitamin B12 availability: it can accumulate when B12-dependent metabolism is impaired. It is particularly useful when serum B12 is borderline or does not fit the symptoms, rather than automatically adding it to every vitamin panel.

An elevated MMA supports B12 deficiency in the right context, but reduced kidney clearance can also raise it. Review creatinine/eGFR, serum B12, symptoms, and supplements together. Unlike homocysteine, MMA is not a marker of folate deficiency.

The laboratory method and kidney function matter more than a single universal cutoff. A high value does not quantify how severe the symptoms or deficiency are; treatment started before testing can complicate interpretation.

Sample: Serum · Fasting: not listed as required

Reference reviewed: 2026-10-26

• MedlinePlus — Methylmalonic acid test ↗
• NIH Office of Dietary Supplements — Vitamin B12 ↗

This panel combines the pituitary signal TSH with total T4, T3 uptake, and a calculated free T4 index. It helps evaluate whether the thyroid is producing too much or too little hormone.

T3 uptake assesses hormone-binding proteins; it is not a measurement of T3 or free T3. The free T4 index uses total T4 and uptake to account for changes in binding. This panel does not include thyroid antibodies.

TSH with a directly measured free T4 is commonly used instead. Pregnancy, estrogen therapy, illness, and assay interference may complicate interpretation; suspected pituitary disease requires a different assessment.

Sample: Serum · Fasting: not listed as required

Reference reviewed: 2026-10-26

• Quest — Thyroid Panel with TSH ↗
• American Thyroid Association — thyroid function tests ↗
• MedlinePlus — T3 uptake ↗

TSH acts like the thyroid’s thermostat: the pituitary raises the signal when it senses too little thyroid hormone and usually lowers it when there is too much. It is usually the first test for suspected primary thyroid dysfunction.

High TSH with low free T4 supports primary hypothyroidism; low TSH with high free T4 supports hyperthyroidism. Abnormal TSH with normal free T4 may indicate a subclinical pattern and often needs confirmation.

TSH alone can miss central (pituitary-related) hypothyroidism. Pregnancy, recent illness, and medicines alter interpretation. High-dose biotin can falsely lower some TSH results; discuss supplements and timing with the laboratory.

Sample: Serum · Fasting: not listed as required

Reference reviewed: 2026-10-26

• MedlinePlus — TSH test ↗
• ARUP — initial thyroid evaluation ↗
• ARUP — thyroid assay interference ↗

Free T3 measures the unbound portion of triiodothyronine, an active thyroid hormone. Its main diagnostic value is investigating suspected hyperthyroidism, especially when TSH is suppressed but free T4 is still normal.

An elevated T3 with low TSH can reveal T3-predominant hyperthyroidism. Conversely, a normal T3 does not exclude hypothyroidism. This is a different test from the T3 uptake included in some thyroid panels.

Free T3 assays are less reliable than some other thyroid measurements; a clinician may prefer total T3. Illness or restricted intake can lower T3 without primary thyroid failure. It is not a stand-alone measure of metabolism or a routine target for levothyroxine adjustment.

Sample: Serum · Fasting: not listed as required

Reference reviewed: 2026-10-26

• American Thyroid Association — T3 testing ↗
• MedlinePlus — T3 tests ↗

Free T4 measures thyroxine that is not attached to blood proteins. It helps interpret an abnormal TSH and distinguish a clear thyroid hormone deficiency or excess from a subclinical pattern.

High TSH plus low free T4 suggests primary hypothyroidism. Low or inappropriately normal TSH with low free T4 can point to a pituitary problem or effects of illness. Free T4 is different from total T4 and the calculated free T4 index.

Use the laboratory’s method- and pregnancy-appropriate interval. Thyroid medicine timing and high-dose biotin can affect results; an unexpected result should be checked before changing treatment.

Sample: Serum · Fasting: not listed as required

Reference reviewed: 2026-10-26

• MedlinePlus — thyroxine test ↗
• MedlinePlus — free T4 ↗
• ARUP — thyroid assay interference ↗

Includes the usual CBC measurements plus a differential: the numbers and proportions of neutrophils, lymphocytes, monocytes, eosinophils, and basophils. This extra detail helps investigate infections, medication effects, and blood or immune disorders.

Absolute cell counts are often more informative than percentages alone. A high percentage may reflect a decrease in another cell type. Eosinophils can rise with allergies or some parasites; neutrophil changes have several possible causes.

The differential does not identify a particular infection or prove an allergy. Stress and medicines can affect counts. A blood smear or further testing may be needed if abnormal or immature cells are suspected.

Sample: Whole blood · Fasting: not listed as required

Reference reviewed: 2026-10-26

• MedlinePlus — Blood differential ↗
• MedlinePlus — Blood differential test ↗
• MedlinePlus — Blood smear ↗

Plasma zinc can help investigate suspected deficiency when there is poor absorption, prolonged inadequate intake, impaired wound healing, or altered taste. These symptoms have many possible causes, so a zinc result is most useful when the history suggests a risk.

Blood zinc is an imperfect snapshot: infection, illness, hormones, and time of day influence it. A low value during inflammation does not necessarily mean low body stores; diet and clinical findings help distinguish these possibilities.

It is not a general measure of immune strength. Excess zinc supplements can interfere with copper absorption and cause copper deficiency, so a higher zinc level is not automatically better.

Sample: Plasma · Fasting: not listed as required

Reference reviewed: 2026-10-26

• NIH Office of Dietary Supplements — Zinc ↗
• NIH Office of Dietary Supplements — Copper ↗

Copper testing can help investigate deficiency associated with malabsorption or excess zinc intake, especially with unexplained anemia or neurologic symptoms. Most circulating copper is carried by ceruloplasmin, a protein that is often measured alongside it.

Copper and ceruloplasmin can rise with inflammation, pregnancy, and estrogen exposure. A raised blood copper level therefore does not by itself establish copper toxicity. Conversely, some disorders of copper handling need specialist tests beyond serum or plasma copper.

Review zinc-containing supplements and nutritional risks. There is no single fully reliable blood marker of total copper status, and the result should not be used alone to diagnose Wilson disease or justify copper supplementation.

Sample: Plasma · Fasting: not listed as required

Reference reviewed: 2026-10-26

• NIH Office of Dietary Supplements — Copper ↗
• ARUP Consult — Wilson disease ↗

Selenium supports enzymes involved in thyroid hormone metabolism and protection from oxidative damage. Blood testing may help assess suspected deficiency or excessive exposure, particularly when nutrition, absorption, or supplement history raises a specific concern.

Serum or plasma selenium mainly reflects recent intake; whole-blood measurements represent a different time window. These specimen types and their reference intervals are not interchangeable. A result should be considered with illness, diet, and all selenium-containing products.

A low-normal level does not establish that supplementation will improve thyroid symptoms or prevent cancer or heart disease. Excess selenium can cause hair loss, brittle nails, gastrointestinal symptoms, and other toxicity; more is not necessarily beneficial.

Sample: Serum · Fasting: not listed as required

Reference reviewed: 2026-10-26

• NIH Office of Dietary Supplements — Selenium ↗

Retinol testing is most useful when vitamin A deficiency is suspected, such as with fat malabsorption or difficulty seeing in dim light. Vitamin A supports vision and healthy tissues; much of the body’s supply is stored in the liver.

Serum retinol can remain normal until liver stores are substantially depleted. Infection and inflammation can lower it even without depleted stores. Thus, a single normal or low result does not precisely measure the amount stored in the body.

Interpret alongside symptoms, absorption problems, and supplement or retinoid use. High-dose preformed vitamin A can be toxic and can harm a developing fetus; a low result is not a reason to self-prescribe large doses.

Sample: Serum · Fasting: yes, confirm instructions

Reference reviewed: 2026-10-26

• NIH Office of Dietary Supplements — Vitamin A ↗

Vitamin E testing can help investigate deficiency when fat absorption is impaired or certain neurologic symptoms suggest it. Alpha-tocopherol is the main form used to assess nutritional vitamin E status, even when the assay reports other tocopherols.

Vitamin E circulates with blood lipids. A high cholesterol or triglyceride level can make the absolute vitamin E concentration look more reassuring than it is; interpretation may require comparison with lipid levels rather than the vitamin result alone.

This is not a general antioxidant or anti-aging score. A higher level does not establish cardiovascular benefit, and high-dose vitamin E can increase bleeding risk, particularly with anticoagulants or antiplatelet medicines.

Sample: Serum · Fasting: yes, confirm instructions

Reference reviewed: 2026-10-26

• NIH Office of Dietary Supplements — Vitamin E ↗

Serum or plasma iodine can help investigate excess iodine exposure, including iodine-containing medicines such as amiodarone. It measures an element used to make thyroid hormones; it does not measure thyroid function itself.

Review recent contrast imaging, supplements, seaweed products, and medicines. Excess iodine can cause either underactive or overactive thyroid function in susceptible people. TSH and free T4 answer the separate question of how the thyroid is responding.

A single blood iodine result should not be treated as a complete assessment of long-term dietary adequacy. Urinary iodine is commonly used for population assessment, but one spot sample is also unreliable for classifying an individual’s usual intake.

Sample: Serum · Fasting: not listed as required

Reference reviewed: 2026-10-26

• Mayo Clinic Laboratories — Serum iodine ↗
• NIH Office of Dietary Supplements — Iodine ↗

The urine albumin-to-creatinine ratio (uACR) detects albumin leakage that may appear before kidney filtration declines. It complements blood creatinine/eGFR, especially in diabetes and hypertension, and also informs cardiovascular risk.

The ratio accounts for urine concentration. A result of 30 mg/g or higher is increased; higher persistent values generally mean greater risk. Check the units: Canadian reports may use mg/mmol instead of mg/g.

Exercise, fever, urinary infection, menstrual contamination, or marked hyperglycemia can cause a temporary increase. An abnormal result usually needs confirmation, preferably with an early-morning sample; chronic kidney disease requires evidence of persistence for at least three months.

Sample: Urine · Fasting: not listed as required

Reference reviewed: 2026-10-26

• NIDDK — Assess urine albumin ↗
• National Kidney Foundation — uACR ↗
• KDIGO 2024 — CKD guideline ↗

The Clauss method measures functional fibrinogen: how well this liver-produced protein contributes to forming a clot. It is useful in selected bleeding evaluations, suspected consumption of clotting factors, or inherited fibrinogen disorders.

Low activity may reflect too little fibrinogen or fibrinogen that does not function normally. A separate fibrinogen antigen measurement can distinguish amount from function when an inherited functional problem is suspected.

Fibrinogen can rise with inflammation and pregnancy. This test is not a general screen for “thick blood” or a stand-alone measure of clot risk. Interpretation may require platelet count and other coagulation tests.

Sample: Whole blood · Fasting: not listed as required

Reference reviewed: 2026-10-26

• Quest Diagnostics — Fibrinogen activity, Clauss ↗
• ARUP — Fibrinogen panel ↗
• MedlinePlus — Fibrinogen blood test ↗

RBC magnesium measures magnesium inside red blood cells, rather than in the liquid serum portion. Magnesium supports muscle, nerve, and enzyme function, but red cells represent only one compartment of the body.

Neither serum nor RBC magnesium gives a complete inventory of body stores. Serum magnesium remains the usual clinical starting point; an RBC result should be interpreted with symptoms, kidney function, intake, and medicines rather than assumed to be a superior test.

No single available magnesium measurement is a satisfactory gold standard for nutritional status. An RBC result does not directly measure magnesium in muscle or brain, and it should not be used to label a universal “optimal” level or dictate supplement dosing.

Sample: Whole blood · Fasting: not listed as required

Reference reviewed: 2026-10-26

• NIH Office of Dietary Supplements — Magnesium ↗

OmegaCheck measures several omega-3 and omega-6 fatty acids in whole blood. Its main omega-3 result combines EPA, DHA, and DPA as a percentage of measured fatty acids, adding information about fatty acid exposure beyond a food-intake estimate.

This is not the same calculation as the RBC Omega-3 Index, which uses EPA plus DHA in red blood cells. Do not transfer thresholds between them. Quest’s risk categories describe associations in study populations, not a diagnosis or an individual prediction.

The result alone does not establish that a particular supplement or dose will prevent a cardiovascular event. Interpret it with the standard lipid profile and overall cardiovascular risk, using the same method when comparing results over time.

Sample: Whole blood · Fasting: not listed as required

Reference reviewed: 2026-10-26

• Quest Diagnostics — OmegaCheck test guide ↗
• Quest Diagnostics — Metabolic testing portfolio ↗

Total IgA measures the amount of one antibody class, rather than antibodies against a particular food or infection. It helps assess selected immune problems and is commonly paired with tTG-IgA when testing for celiac disease.

If total IgA is very low, an IgA-based celiac test can be falsely reassuring. An IgG-based test may then be needed. A normal total IgA makes the IgA-based result easier to interpret but does not itself rule out celiac disease.

Low or high IgA is not a complete immune-system diagnosis. It may need review alongside other immunoglobulins, infection history, age-specific ranges, and medicines. It is not an overall “immunity score.”

Sample: Serum · Fasting: not listed as required

Reference reviewed: 2026-10-26

• MedlinePlus — Immunoglobulins ↗
• NIDDK — Celiac disease tests ↗

tTG-IgA is generally the first blood test for suspected celiac disease when total IgA is sufficient. It detects an autoimmune response linked to gluten-related intestinal injury, including in people with unexplained iron deficiency or chronic digestive symptoms.

A positive result supports further celiac assessment; confirmation depends on the antibody level, age, and clinical pathway, often including intestinal biopsy. A negative result is less reliable with IgA deficiency or limited gluten intake.

Testing is most informative while eating gluten. Do not start a gluten-free diet before the evaluation without discussing it. This test does not diagnose wheat allergy or non-celiac gluten sensitivity.

Sample: Serum · Fasting: not listed as required

Reference reviewed: 2026-10-26

• ARUP Consult — Celiac disease ↗
• Celiac Canada — Screening and diagnosis ↗

Deamidated gliadin peptide (DGP) antibodies recognize modified gluten fragments. Their main added value is in selected celiac investigations, particularly the IgG component when total IgA is deficient.

When total IgA is adequate, tTG-IgA is generally preferred for initial screening; adding DGP automatically does not always improve diagnostic accuracy. DGP results can help resolve selected uncertain patterns, with specialist interpretation.

A positive result alone does not establish celiac disease. Low gluten intake can reduce antibody levels, and a negative test may not exclude disease when suspicion remains high. These are targeted celiac antibodies, not a broad food-IgG intolerance panel.

Sample: Serum · Fasting: not listed as required

Reference reviewed: 2026-10-26

• ARUP Laboratories — DGP IgA and IgG ↗
• ARUP Consult — Celiac disease testing algorithm ↗

ESR measures how far red blood cells settle in one hour, reported in mm/hour. Inflammatory proteins can make the cells settle faster. It is used in selected inflammatory conditions and to follow disease activity over time.

An elevated ESR supports an inflammatory pattern but cannot locate it or identify its cause. Changes are interpreted with symptoms, examination, and sometimes CRP; a normal result does not exclude every inflammatory disease.

Age, pregnancy, anemia, kidney disease, and red-cell characteristics can affect ESR independently of the condition being investigated. It is not a general wellness score or a useful reason by itself to order a large battery of tests.

Sample: Whole blood · Fasting: not listed as required

Reference reviewed: 2026-10-26

• MedlinePlus — ESR test ↗
• MedlinePlus — ESR clinical overview ↗

Estradiol is an estrogen involved in reproductive function and bone health. Testing can help investigate absent periods, ovarian function, or breast enlargement in men, and answer specific questions during hormone treatment.

This ultrasensitive mass-spectrometry method is useful when low concentrations are expected, such as in men or after menopause. Results should be compared with the appropriate cycle phase and interpreted alongside FSH/LH when relevant.

Levels fluctuate substantially during the menstrual cycle. One sample does not define overall “hormone balance” or establish fertility. Record cycle day and hormone medicines; laboratory estradiol may not reflect every estrogen in a medication.

Sample: Serum · Fasting: not listed as required

Reference reviewed: 2026-10-26

• Quest — ultrasensitive estradiol ↗
• Quest — method selection at low estradiol levels ↗
• MedlinePlus — estradiol ↗

Progesterone rises after an egg is released. A properly timed test can help establish that ovulation occurred; it is also used for selected pregnancy or fertility-treatment questions.

For ovulation assessment, timing should follow the individual cycle, around the mid-luteal phase (about a week after ovulation), not automatically “day 21.” A luteal value above 3 ng/mL (about 9.5 nmol/L) supports recent ovulation; it is not a target for pregnancy success.

Progesterone is released in pulses. A single result cannot assess the quality of the luteal phase or confirm that a pregnancy is viable. Hormonal medicines and pregnancy change interpretation.

Sample: Serum · Fasting: not listed as required

Reference reviewed: 2026-10-26

• ASRM — luteal phase deficiency and progesterone interpretation ↗
• MedlinePlus — progesterone test ↗

Total testosterone includes both protein-bound and free hormone. It helps investigate suspected testosterone deficiency in men or androgen excess in women. Mass spectrometry is particularly useful at low concentrations, where some immunoassays are less accurate.

For suspected deficiency in adult men, symptoms plus consistently low levels are needed: confirm an initial low result on a separate early-morning, fasting sample. SHBG can change total testosterone without a matching change in free hormone.

Acute illness, sleep disruption, medicines, and hormone use affect results. Routine testing of all asymptomatic men is not recommended; a low result alone is not an indication for testosterone treatment.

Sample: Serum · Fasting: not listed as required

Reference reviewed: 2026-10-26

• Endocrine Society — testosterone guideline ↗
• Quest — testosterone testing methods ↗

Free testosterone is the small fraction not attached to blood proteins. It can clarify borderline total testosterone or a result that does not fit symptoms, especially when SHBG, the main binding protein, is altered.

Quest code 18944 calculates free testosterone from total testosterone, SHBG, and albumin measurements. This is different from directly separating free hormone by equilibrium dialysis. The calculation helps interpret the free fraction when binding-protein levels make total testosterone misleading.

Reference intervals depend on the method and units. Do not compare calculated, direct immunoassay, and dialysis results as if interchangeable. For suspected deficiency in men, interpretation still requires symptoms and appropriately timed, confirmed testosterone measurements.

Sample: Serum · Fasting: not listed as required

Reference reviewed: 2026-10-26

• Quest — code 18944, calculated free testosterone ↗
• ARUP — free testosterone methods ↗

DHEA-S is made mainly by the adrenal glands and is a precursor of other sex hormones. Its main value is helping investigate excess androgen effects, such as new coarse facial hair, acne, or changes in sexual development.

An elevated result can suggest an adrenal contribution to androgen excess, interpreted with testosterone and other targeted tests. Levels normally decline with age, so comparison with young-adult values may be misleading.

A low value does not by itself diagnose adrenal insufficiency or “adrenal fatigue,” and is not a reason to start DHEA. This is not a validated anti-aging score; supplements can affect results and cause adverse effects.

Sample: Serum · Fasting: not listed as required

Reference reviewed: 2026-10-26

• MedlinePlus — DHEA sulfate test ↗
• MedlinePlus — DHEA-sulfate interpretation ↗
• Endocrine Society — adrenal fatigue ↗

SHBG is a liver-produced transport protein that binds testosterone and estradiol. Measuring it helps explain why total hormone levels may not reflect the amount of free hormone available to tissues.

For the same total testosterone, higher SHBG generally means a lower free fraction, and lower SHBG a higher free fraction. SHBG and total testosterone, sometimes with albumin, can be used to calculate free testosterone.

Obesity, thyroid or liver disease, estrogen exposure, and other medicines can alter SHBG. It is an aid to hormone interpretation, not a stand-alone diagnosis of hormone deficiency, excess, or polycystic ovary syndrome.

Sample: Serum · Fasting: not listed as required

Reference reviewed: 2026-10-26

• MedlinePlus — SHBG blood test ↗
• Quest — calculated free testosterone ↗

Prolactin stimulates milk production. Outside pregnancy and breastfeeding, persistently high levels can disrupt menstrual cycles, fertility, libido, and testosterone production, making this test useful for those specific problems.

A raised result does not automatically mean a pituitary tumour. Medicines, hypothyroidism, kidney disease, and stress are other explanations. Mild unexpected elevations may need a repeat sample under suitable conditions before further investigation.

Macroprolactin, a larger and usually less active form, can elevate the reported result. When symptoms and results disagree, the laboratory can assess this separately. Do not stop a suspected medicine without discussing alternatives with its prescriber.

Sample: Serum · Fasting: not listed as required

Reference reviewed: 2026-10-26

• MedlinePlus — prolactin levels ↗
• ARUP — macroprolactin ↗
• Royal United Hospitals Bath — hyperprolactinaemia guidance ↗

IGF-1 reflects growth-hormone activity over time more steadily than a random growth-hormone level, which rises and falls in pulses. It helps investigate suspected growth-hormone excess, such as acromegaly, and selected deficiency questions.

Compare with an age-appropriate interval. A Z-score expresses how far the result is from the expected value for the reference group; it is not a biological-age score. Unexpectedly high levels may need repeat testing and specialist confirmatory tests.

Nutrition, liver or kidney disease, uncontrolled diabetes, and oral estrogen can change IGF-1. A low value alone does not prove growth-hormone deficiency, and this is not a general test for longevity or a reason to seek higher levels.

Sample: Serum · Fasting: not listed as required

Reference reviewed: 2026-10-26

• ARUP — acromegaly and IGF-1 interpretation ↗
• MedlinePlus — IGF-1 test ↗
• Quest — IGF-1 and Z-score interpretation ↗

FSH and LH are pituitary signals to the ovaries or testes. Together with estradiol or testosterone, they help locate a reproductive hormone problem: in the reproductive glands themselves or in the signals controlling them.

Low sex hormones with high FSH/LH suggest reduced ovarian or testicular response. Low sex hormones with low or inappropriately normal FSH/LH suggest a central cause. LH normally surges around ovulation; high FSH is expected after menopause.

Cycle phase and hormone medicines matter. A single measurement does not establish fertility or predict time to menopause. Typical menopause after age 45 usually does not need hormone testing; testing is more useful for early or uncertain presentations.

Sample: Serum · Fasting: not listed as required

Reference reviewed: 2026-10-26

• MedlinePlus — FSH levels ↗
• MedlinePlus — LH levels ↗
• NICE NG23 - menopause identification (updated guidance) ↗

DHT is made from testosterone by the enzyme 5-alpha-reductase. It contributes to androgen effects in tissues such as skin, hair follicles, and the prostate. Testing has focused uses, including investigation of rare defects in testosterone-to-DHT conversion.

Finasteride and dutasteride reduce DHT by blocking this conversion, so a low result during treatment can be expected. Interpretation may require testosterone and the clinical question rather than the DHT value alone.

Blood DHT does not reliably represent androgen action inside tissues. A normal result does not rule out androgen-related hair loss, and a high result alone does not prove its cause. There is no universal “optimal DHT” target for general health.

Sample: Serum · Fasting: not listed as required

Reference reviewed: 2026-10-26

• Mayo Clinic Laboratories — DHT clinical interpretation ↗
• Primary study — circulating DHT and tissue action ↗

PSA is a protein made by prostate tissue. It is used in selected screening decisions, evaluation of prostate concerns, and follow-up after prostate cancer treatment. It is specific to the prostate, not specific to cancer.

A raised level can reflect benign enlargement, inflammation, or cancer. There is no single cutoff that reliably separates cancer from noncancer; an unexpected screening elevation is often repeated before decisions about imaging or biopsy.

Finasteride/dutasteride lower PSA; infection and recent ejaculation can raise it. Screening should follow discussion of possible benefit, false alarms, and overdiagnosis, considering age, risk, and preferences. A normal PSA cannot completely exclude cancer.

Sample: Serum · Fasting: not listed as required

Reference reviewed: 2026-10-26

• National Cancer Institute — PSA fact sheet ↗
• NHS — PSA testing ↗