Blood tests are among the most commonly performed medical tests. They are used to screen for disease, monitor known conditions, follow treatment progress, and check organ function. The results can include dozens of individual measurements, and most patients receive their report with little or no explanation of what each number means.
This section provides plain-language guides to the most common blood tests. Each article explains what the test measures, why it is ordered, what the typical results mean, and what may need to happen next.
If you are looking for a definition of a single laboratory term, visit our Pathology Dictionary. If you are looking for a guide to a specific cancer biomarker, visit our Biomarkers and Molecular Testing section.
Important note about reference ranges
The reference range that applies to your result is the one printed on your laboratory report, not the typical ranges shown in these articles. Reference ranges vary between laboratories based on the equipment used, the population tested, and individual factors such as age, sex, and pregnancy status. Always compare your result to the reference range printed on your own report, and discuss any abnormal result with your doctor.
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Common Blood Test Panels
Understanding your complete blood count (CBC)
A guide to the most commonly ordered blood test, including red blood cell count, hemoglobin, hematocrit, white blood cell count, platelets, and the indices that describe red blood cell size and content.
You may find this helpful if your blood test report includes terms like RBC, HGB, HCT, MCV, MCH, MCHC, RDW, WBC, PLT, or MPV.
Understanding your white blood cell differential
A guide to the breakdown of white blood cell types in your blood — neutrophils, lymphocytes, monocytes, eosinophils, and basophils — and what high or low counts of each can mean.
You may find this helpful if your report includes a differential count, an absolute neutrophil count (ANC), or terms like neutrophilia, lymphocytosis, or eosinophilia.
Understanding your basic metabolic panel (BMP)
A guide to the eight measurements on a basic metabolic panel, including sodium, potassium, chloride, bicarbonate, blood urea nitrogen, creatinine, glucose, and calcium.
You may find this helpful if your blood test report includes electrolytes, kidney function tests, or a fasting glucose result as part of a routine blood panel.
Understanding your comprehensive metabolic panel (CMP)
A guide to the comprehensive metabolic panel, which expands on the basic metabolic panel by adding albumin, total protein, and the liver enzymes ALP, ALT, and AST, along with bilirubin.
You may find this helpful if your blood test was ordered as a CMP or “chem 14” and includes both kidney and liver-related measurements.
Understanding your liver panel
A guide to liver function and liver injury tests, including ALT, AST, ALP, GGT, LDH, bilirubin, albumin, total protein, and prothrombin time, and what their patterns of elevation can suggest.
You may find this helpful if your blood test report includes liver enzymes, abnormal bilirubin, or a flagged result for ALT or AST.
Understanding your lipid panel
A guide to cholesterol and triglyceride testing, including total cholesterol, LDL, HDL, non-HDL cholesterol, and triglycerides, with explanations of what each measurement reflects about cardiovascular risk.
You may find this helpful if your blood test report includes a cholesterol panel or your doctor discussed cardiovascular risk based on your blood results.
Understanding your kidney function tests
A guide to the blood tests used to assess kidney function, including creatinine, blood urea nitrogen (BUN), estimated glomerular filtration rate (eGFR), cystatin C, and creatinine clearance.
You may find this helpful if your blood test report includes an eGFR, a creatinine result, or your doctor discussed your kidney function based on your blood test.
Understanding your thyroid function tests
A guide to thyroid blood testing, including TSH, free T3, free T4, and thyroid antibodies, and what abnormal results may suggest about thyroid function and autoimmune thyroid disease.
You may find this helpful if your blood test report includes a TSH result, your doctor mentioned hypothyroidism or hyperthyroidism, or you have been screened for thyroid antibodies.
Understanding your coagulation panel
A guide to blood clotting tests, including prothrombin time (PT), international normalized ratio (INR), and partial thromboplastin time (PTT), and how these tests are used to monitor blood thinners and assess bleeding risk.
You may find this helpful if your report includes PT, INR, or PTT results, or if you are taking warfarin or another anticoagulant.
A guide to the blood tests used to assess iron levels and storage, including serum iron, ferritin, transferrin, total iron-binding capacity (TIBC), and transferrin saturation.
You may find this helpful if your blood test report includes a ferritin result, your doctor mentioned iron deficiency or iron overload, or you have been investigated for anemia.
Diabetes and Glucose Testing
Understanding your hemoglobin A1c (HbA1c) result
A guide to the HbA1c test, which measures average blood glucose over the past two to three months and is used to diagnose and monitor diabetes.
You may find this helpful if your blood test report includes an HbA1c result, your doctor diagnosed prediabetes or diabetes, or you are using A1c to track your blood sugar control over time.
Understanding your fasting glucose and oral glucose tolerance test (OGTT) (coming soon)
A guide to the fasting plasma glucose test and the oral glucose tolerance test, two of the most common blood tests used to detect diabetes and gestational diabetes.
You may find this helpful if you have had a fasting blood sugar test or a glucose tolerance test during pregnancy or for diabetes screening.
Cardiac and Inflammatory Markers
Understanding cardiac biomarkers in your blood test (coming soon)
A guide to the blood tests used to detect heart muscle damage and heart failure, including troponin, BNP, NT-proBNP, creatine kinase (CK), and CK-MB.
You may find this helpful if you had a blood test for chest pain, a suspected heart attack, or to monitor heart failure.
Understanding your inflammatory markers (coming soon)
A guide to blood tests that measure inflammation in the body, including C-reactive protein (CRP), erythrocyte sedimentation rate (ESR), and ferritin as a marker of inflammation.
You may find this helpful if your blood test report includes CRP or ESR results, or if your doctor discussed inflammation in the context of an autoimmune or infectious condition.
Hormone Tests
Understanding your reproductive hormone panel (coming soon)
A guide to the blood tests used to assess fertility and reproductive health, including follicle-stimulating hormone (FSH), luteinizing hormone (LH), estradiol, progesterone, testosterone, free testosterone, sex hormone-binding globulin (SHBG), anti-Mullerian hormone (AMH), and prolactin.
You may find this helpful if your blood test report includes hormone results, you are being investigated for infertility or menstrual irregularities, or you are receiving gender-affirming care.
Understanding your adrenal hormone tests (coming soon)
A guide to blood tests of the adrenal glands, including cortisol, adrenocorticotropic hormone (ACTH), and aldosterone, and what abnormal results may suggest about adrenal function.
You may find this helpful if your blood test report includes cortisol or ACTH results, or your doctor mentioned Addison’s disease, Cushing’s syndrome, or adrenal insufficiency.
Understanding your parathyroid hormone (PTH) and calcium balance tests (coming soon)
A guide to the blood tests used to assess calcium balance, including parathyroid hormone (PTH), ionized calcium, phosphorus, and vitamin D.
You may find this helpful if your blood test report includes a PTH or vitamin D result, your calcium level was abnormal, or your doctor discussed bone health, kidney stones, or parathyroid disease.
Tumour Markers
Understanding tumour markers in your blood test (coming soon)
A comprehensive guide to the blood tests used to detect or monitor cancer, including PSA (prostate), AFP (liver and germ cell), CEA (colorectal and others), CA 19-9 (pancreas), CA 125 (ovary), CA 15-3 and CA 27-29 (breast), beta-HCG (germ cell and gestational), calcitonin (medullary thyroid), and thyroglobulin (thyroid).
You may find this helpful if your blood test report includes a tumour marker result, your doctor is using a tumour marker to monitor a known cancer, or you are being screened for a specific type of cancer.
Understanding your prostate-specific antigen (PSA) result (coming soon)
A guide to the PSA test, including how it is used for prostate cancer screening and monitoring, what factors can raise PSA levels, and how PSA is interpreted in the context of prostate biopsy results and active surveillance.
You may find this helpful if your blood test includes a PSA result, you are being screened for prostate cancer, or you are following PSA results during or after treatment.
Autoimmune and Specialty Tests
Understanding your autoimmune panel (coming soon)
A guide to the blood tests used to detect autoimmune diseases, including antinuclear antibody (ANA), anti-double-stranded DNA, rheumatoid factor, anti-CCP, anti-tissue transglutaminase, anti-LKM-1, and smooth muscle antibody (SMA).
You may find this helpful if your blood test report includes autoimmune antibody results, or your doctor is investigating lupus, rheumatoid arthritis, autoimmune hepatitis, or another autoimmune condition.
Understanding your celiac disease testing (coming soon)
A guide to the blood tests used to screen for and help diagnose celiac disease, including anti-tissue transglutaminase IgA (anti-TTG IgA), anti-endomysial antibodies, deamidated gliadin peptide antibodies, and total IgA.
You may find this helpful if your blood test report includes celiac antibody results, or you are being investigated for unexplained gastrointestinal symptoms, anemia, or nutrient deficiencies.
Infectious Disease Testing
Understanding your COVID-19 test results (coming soon)
A guide to the three main types of COVID-19 testing — molecular (PCR) tests, antigen tests, and antibody tests — and what each result means for active infection, past infection, and immunity.
You may find this helpful if you have had a COVID-19 test and need to understand whether the result indicates active infection, past infection, or immunity.
Understanding your HIV and hepatitis testing (coming soon)
A guide to the blood tests used to screen for and confirm HIV and viral hepatitis (A, B, and C), including what antibody, antigen, and viral load results mean.
You may find this helpful if your blood test report includes HIV or hepatitis screening results, or your doctor discussed liver disease in the context of viral hepatitis.
Transplant and Compatibility Testing
Understanding your blood typing and compatibility tests (coming soon)
A guide to the blood tests used before a transfusion or pregnancy, including ABO blood typing, Rh factor testing, antibody screening, and crossmatching.
You may find this helpful if you had blood typing before surgery or a transfusion, you are pregnant, and your blood was tested for Rh status, or you have received a transfusion reaction workup.
Understanding your transplant compatibility tests (coming soon)
A guide to the blood tests used to match donors and recipients before organ transplantation, including human leukocyte antigen (HLA) typing, donor-specific antibodies (DSA), and panel reactive antibodies (PRA).
You may find this helpful if you are awaiting an organ transplant or have received one, and your reports include HLA typing, DSA testing, or PRA results.
Specialized Blood Reports
Understanding your peripheral blood smear (coming soon)
A guide to the peripheral blood smear, a test in which blood is examined under a microscope to identify abnormalities in the size, shape, and appearance of red blood cells, white blood cells, and platelets.
You may find this helpful if your blood test report includes findings from a peripheral blood smear, or your doctor ordered the smear after an unusual CBC result.
Understanding your hemoglobin disorder tests (coming soon)
A guide to the blood tests used to detect inherited hemoglobin disorders such as sickle cell disease and thalassemia, including hemoglobin electrophoresis, high-performance liquid chromatography (HPLC), hemoglobin solubility testing, and the sodium metabisulfite test.
You may find this helpful if you have had screening for sickle cell disease or thalassemia, or your blood test report includes hemoglobin variant analysis.
Don’t see your blood test listed?
New blood test guides are added regularly. In the meantime, our Pathology Dictionary defines many laboratory test terms, and Osler, our pathology chatbot, can help explain specific results from your report in plain language.
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