Blood Test Guide
What your blood test numbers mean — MCV, MCH, RDW, ALT, AST, BUN, creatinine, eGFR, and more. Understand your lab results.
What Is MCHC in a Blood Test?
Learn what MCHC means in a blood test: normal range, what causes low MCHC levels (iron-deficiency anemia, thalassemia), and how abnormal res…
What Is MCV in a Blood Test?
Understand MCV (Mean Corpuscular Volume) in your blood test: normal range, causes of high and low MCV values, and how your doctor uses MCV a…
What Is RDW in a Blood Test?
Learn what RDW means in your blood test: normal range, when high RDW indicates iron deficiency or B12/folate deficiency, and how it helps do…
What Is ALT in a Blood Test?
Understand ALT (alanine aminotransferase) in your blood test: normal range, what elevated ALT means for your liver health, common causes lik…
What Is BUN in a Blood Test?
Learn what BUN (blood urea nitrogen) means in your blood test: normal range, causes of high and low BUN levels, BUN-to-creatinine ratio, and…
What Is MPV in a Blood Test?
MPV (Mean Platelet Volume) explained: normal range 7.5-11.5 fL, what high and low MPV means for platelet function and clotting.…
What Is AST in a Blood Test?
AST (Aspartate Aminotransferase) explained: normal range 10-40 U/L, what elevated AST means for liver disease, heart damage, muscle injury, …
What Is eGFR in a Blood Test?
eGFR (estimated Glomerular Filtration Rate) explained: normal above 90 mL/min, kidney disease stages 1-5, what low eGFR means, and how age/s…
What Is Creatinine in a Blood Test?
Creatinine explained: normal range 0.6-1.3 mg/dL, what high creatinine means for kidney function, how muscle mass affects it, and its relati…
What Is Hemoglobin in a Blood Test?
Hemoglobin explained: normal ranges (men 13.5-17.5, women 12-15.5 g/dL), what low hemoglobin (anemia) and high hemoglobin mean, symptoms, an…
What Is Hematocrit (HCT) in a Blood Test?
Hematocrit explained: normal ranges (men 38.8-50%, women 34.9-44.5%), what high and low HCT means, and how it relates to hemoglobin and red …
What Is WBC (White Blood Cell Count) in a Blood Test?
WBC explained: normal range 4,500-11,000/µL, what high WBC (infection, inflammation) and low WBC (bone marrow suppression, viral infection) …
What Is Platelet Count in a Blood Test?
Platelet count explained: normal range 150,000-450,000/µL, what low platelets (thrombocytopenia — bleeding risk) and high platelets (thrombo…
What Are Neutrophils in a Blood Test?
Neutrophils explained: normal range 2,500-7,000/µL (40-60% of WBC), what high neutrophils (bacterial infection, stress) and low neutrophils …
What Are Lymphocytes in a Blood Test?
Lymphocytes explained: normal range 1,000-4,800/µL (20-40% of WBC), what high lymphocytes (viral infection, leukemia) and low lymphocytes (H…
What Is Ferritin in a Blood Test?
Ferritin explained: normal ranges (men 20-500, women 20-200 ng/mL), what low ferritin means (iron deficiency before anemia), what high ferri…
What Is Vitamin D in a Blood Test?
Vitamin D (25-OH) explained: optimal range 30-50 ng/mL, deficiency below 20 ng/mL, causes, symptoms (bone pain, fatigue), and supplementatio…
What Is Vitamin B12 in a Blood Test?
Vitamin B12 explained: normal range 200-900 pg/mL, deficiency symptoms (fatigue, neuropathy, macrocytosis), causes (pernicious anemia, vegan…
What Is CRP in a Blood Test?
CRP (C-Reactive Protein) explained: normal below 3 mg/L, what high CRP means (infection, inflammation, cardiovascular risk), and the differe…
What Is ESR in a Blood Test?
ESR (Erythrocyte Sedimentation Rate) explained: normal ranges by age/sex, what elevated ESR means (inflammation, autoimmune, cancer), and ho…
What Is Uric Acid in a Blood Test?
Uric acid explained: normal ranges (men 3.4-7.2, women 2.4-6.0 mg/dL), what high uric acid means (gout, kidney stones, metabolic syndrome), …
What Is Glucose in a Blood Test?
Blood glucose explained: fasting normal 70-99 mg/dL, prediabetes 100-125, diabetes above 126; random glucose, HbA1c relationship, and what a…
What Is HbA1c in a Blood Test?
HbA1c explained: normal below 5.7%, prediabetes 5.7-6.4%, diabetes 6.5%+; how it reflects 3-month average glucose and why it is the gold sta…
What Is Potassium in a Blood Test?
Potassium explained: normal range 3.5-5.1 mEq/L, what high potassium (hyperkalemia — heart rhythm risk) and low potassium (hypokalemia — wea…
What Is Sodium in a Blood Test?
Sodium explained: normal range 135-145 mEq/L, what low sodium (hyponatremia — confusion, seizures) and high sodium (hypernatremia — dehydrat…
What Is Calcium in a Blood Test?
Blood calcium explained: normal range 8.5-10.5 mg/dL, what high calcium (hyperparathyroidism, cancer) and low calcium (vitamin D deficiency)…
What Is Albumin in a Blood Test?
Albumin explained: normal range 3.5-5.0 g/dL, what low albumin means (liver disease, kidney disease, malnutrition) and what high albumin mea…
What Is Bilirubin in a Blood Test?
Bilirubin explained: normal range 0.3-1.2 mg/dL, what high bilirubin means (jaundice, liver disease, Gilbert syndrome, hemolysis), and direc…
What Is a TSH Blood Test?
TSH blood test explained: what it measures, normal range (0.4-4.0 mIU/L), when to test, and why it is the first-line thyroid screening test.…
What Is Free T4 in a Blood Test?
Free T4 (free thyroxine) explained: normal range 0.8-1.8 ng/dL, how it differs from total T4, and how it is used with TSH to diagnose thyroi…
What Is Free T3 in a Blood Test?
Free T3 (free triiodothyronine) explained: normal range 2.3-4.2 pg/mL, how T3 is the active thyroid hormone, and T3 vs T4 vs reverse T3.…
What Are Thyroid Antibodies in a Blood Test?
Thyroid antibodies explained: anti-TPO (Hashimoto's), TSI (Graves' disease), anti-thyroglobulin — what positive antibodies mean for autoimmu…
What Is Testosterone in a Blood Test?
Testosterone testing explained: normal total testosterone ranges, free vs total testosterone, when to test (morning fasting), and what low a…
What Is Cortisol in a Blood Test?
Cortisol testing explained: normal morning range 6-23 µg/dL, why timing matters, what high cortisol (Cushing's) and low cortisol (Addison's)…
What Is a Ferritin Blood Test For?
What a ferritin blood test measures and why it is ordered: iron stores, diagnosing iron deficiency before anemia, monitoring supplementation…
What Is an Iron Blood Test?
Iron blood test panel explained: serum iron, TIBC, transferrin saturation, and ferritin — what each measures and how they work together.…
What Is TIBC in a Blood Test?
TIBC (Total Iron Binding Capacity) explained: normal range 240-450 µg/dL, what high TIBC means (iron deficiency) and what low TIBC means (ir…
What Is Homocysteine in a Blood Test?
Homocysteine explained: normal range 5-15 µmol/L, what high homocysteine means for cardiovascular risk, B12/folate status, and how to lower …
What Is a Full Blood Panel?
What a full blood panel (CBC + CMP) includes: complete blood count, metabolic panel, and what this combination screens for.…
How to Read a Blood Test: Understanding Your Lab Results
A practical guide to reading blood test results: reference ranges, H/L flags, which numbers matter most, and when to follow up.…
What Is Magnesium in a Blood Test?
Magnesium explained: normal range 1.7-2.2 mg/dL, what low magnesium means (muscle cramps, arrhythmia, weakness), and why serum magnesium may…
What Blood Tests Diagnose Iron Deficiency?
Iron deficiency is diagnosed with ferritin (best single marker), TIBC, transferrin saturation, serum iron, CBC (hemoglobin, MCV), and someti…
What Does High Liver Enzymes Mean?
Elevated liver enzymes (ALT, AST, ALP, GGT) explained: common causes including fatty liver, medications, alcohol, viral hepatitis, and when …
What Does a Kidney Function Test Show?
Kidney function tests explained: creatinine, eGFR, BUN, and urine albumin — what they measure, how they detect kidney disease, and normal va…
What Is Iron in a Blood Test?
Serum iron explained: normal range 60-170 µg/dL, what it measures, why it fluctuates, and why it should be interpreted with ferritin and TIB…
What Is TSH in a Blood Test?
TSH (thyroid-stimulating hormone) explained: the most sensitive test for thyroid function, normal range, and what high and low levels mean.…
What Is a Mono Blood Test?
Mononucleosis (mono) testing explained: Monospot test, EBV antibody panel, and atypical lymphocytes on CBC. Symptoms include fatigue, sore t…
What Is an ANA Blood Test?
ANA (Antinuclear Antibody) test explained: what it screens for (lupus, autoimmune disease), what a positive result means, and why many healt…
What Is a T4 Blood Test?
T4 (thyroxine) blood test explained: the main thyroid hormone, normal total and free T4 ranges, and how it is used with TSH.…
What Is a Lipid Panel?
Lipid panel explained: total cholesterol, LDL, HDL, and triglycerides — normal ranges, cardiovascular risk, fasting requirements, and non-HD…
What Is a Thyroid Panel?
Thyroid panel explained: TSH, free T4, free T3, and thyroid antibodies — which tests are included, what each measures, and when a full panel…
What Is Vitamin D Deficiency?
Vitamin D deficiency explained: levels below 20 ng/mL, symptoms (bone pain, fatigue, weakness), causes (limited sun, dark skin, obesity), an…
What Does High WBC in a Blood Test Mean?
High WBC (leukocytosis) explained: above 11,000/µL, common causes including bacterial infection, inflammation, stress, and when very high WB…
What Does Low WBC in a Blood Test Mean?
Low WBC (leukopenia) explained: below 4,000/µL, causes including viral infection, chemotherapy, autoimmune disease, and when low WBC increas…
What Is a Basic Metabolic Panel (BMP)?
BMP explained: 8 tests for kidney function, electrolytes, and glucose. How it differs from CMP (which adds 6 liver tests) and when each is o…
How to Lower Cholesterol Naturally
Evidence-based ways to lower cholesterol without medication: dietary changes (fiber, omega-3s, plant sterols), exercise, weight loss, and qu…
What Is a CBC Blood Test?
CBC (Complete Blood Count) explained: measures red blood cells, white blood cells, and platelets — the most common blood test ordered and wh…
What Is a CMP Blood Test?
CMP (Comprehensive Metabolic Panel) explained: 14 blood tests covering kidney, liver, electrolytes, protein, and glucose — the most comprehe…
What Is LDL Cholesterol?
LDL (low-density lipoprotein) explained: the 'bad' cholesterol, optimal levels below 100 mg/dL, why high LDL causes heart disease, and how t…
What Is HDL Cholesterol?
HDL (high-density lipoprotein) explained: the 'good' cholesterol that removes LDL from arteries, optimal levels above 60 mg/dL, and how to r…
What Are Triglycerides in a Blood Test?
Triglycerides explained: normal below 150 mg/dL, what high triglycerides means (pancreatitis risk, cardiovascular disease), causes (alcohol,…
What Is a Normal Fasting Blood Sugar Level?
Fasting blood sugar explained: normal 70-99 mg/dL, prediabetes 100-125, diabetes 126+. How to prepare for a fasting glucose test and what re…
What Is a TSH Blood Test For?
A TSH blood test screens for thyroid dysfunction: high TSH = hypothyroidism, low TSH = hyperthyroidism. It is the most sensitive thyroid scr…
What Is a Thyroid Blood Test?
Thyroid blood tests explained: TSH (screening), free T4, free T3, and thyroid antibodies — which tests are included and what each one measur…
What Is a Normal Fasting Blood Sugar Level?
Fasting blood sugar: normal 70-99 mg/dL, prediabetes 100-125, diabetes 126+. How to prepare and what results mean.…
What Is a Vitamin B12 Blood Test?
Vitamin B12 test: normal 200-900 pg/mL, deficiency symptoms (fatigue, neuropathy, macrocytosis), causes (pernicious anemia, vegan, metformin…
What Are Basophils in a Blood Test?
Basophils: the rarest WBC (0.5-1%). High basophils suggest allergic reactions or myeloproliferative disorders.…
What Are Eosinophils in a Blood Test?
Eosinophils: WBCs that fight parasites and cause allergic inflammation. High eosinophils = allergies, asthma, parasitic infection, or drug r…
What Are Monocytes in a Blood Test?
Monocytes: WBCs that become macrophages, engulfing debris and pathogens. High monocytes suggest chronic infection, inflammation, or recovery…
What Is RBC Count in a Blood Test?
RBC count measures the number of red blood cells. Normal 4.5-5.9 million/µL (men), 4.1-5.1 (women). Related to hemoglobin and hematocrit.…
What Is Mean Platelet Volume (MPV)?
MPV measures average platelet size. High MPV = younger, larger platelets (increased production). Low MPV = older, smaller platelets (decreas…
What Is the Neutrophil-to-Lymphocyte Ratio (NLR)?
NLR = neutrophils ÷ lymphocytes. Normal 1-3. Elevated NLR indicates inflammation and is associated with worse outcomes in cardiovascular dis…
What Is a Reticulocyte Count?
Reticulocytes are immature red blood cells. The count shows how actively your bone marrow produces new red cells. High = marrow compensating…
What Does Low Hemoglobin Mean?
Low hemoglobin (below 12-13.5 g/dL) = anemia. Common causes: iron deficiency, blood loss, B12/folate deficiency, chronic disease. Symptoms: …
What Does Low Platelet Count Mean?
Low platelets (thrombocytopenia): below 150,000/µL. Causes: ITP, medications, liver disease, alcohol. Below 20,000 = spontaneous bleeding ri…
What Does High Platelet Count Mean?
High platelets (thrombocytosis): above 450,000/µL. Usually reactive to infection, iron deficiency, or inflammation. Rarely a bone marrow dis…
What Does High Creatinine Mean?
High creatinine (above 1.3 mg/dL) suggests impaired kidney filtration. Causes: chronic kidney disease, dehydration, medications. Always chec…
What Does Low eGFR Mean?
eGFR below 60 mL/min for 3+ months = chronic kidney disease. Below 30 = severe. Below 15 = kidney failure requiring dialysis or transplant.…
What Is the Difference Between Direct and Indirect Bilirubin?
Indirect (unconjugated) bilirubin rises with hemolysis or Gilbert syndrome. Direct (conjugated) rises with bile duct obstruction or liver di…
What Is Globulin in a Blood Test?
Globulins are blood proteins including antibodies. High globulin suggests infection, inflammation, or plasma cell disorders. Low globulin su…
What Is a GFR Blood Test?
GFR (glomerular filtration rate) measures kidney filtering. Normal above 90. Below 60 for 3 months = chronic kidney disease.…
What Does Low MCHC Mean?
Low MCHC (below 32 g/dL) means red blood cells have less hemoglobin than normal (hypochromia). Usually indicates iron deficiency anemia.…
What Does High MCHC Mean?
High MCHC (above 36 g/dL) is uncommon. Causes: hereditary spherocytosis, severe burns, autoimmune hemolytic anemia, or lab artifact.…
What Does Low Lymphocytes Mean?
Low lymphocytes (lymphopenia): below 1,000/µL. Causes: HIV, corticosteroids, chemotherapy, severe infection, autoimmune disease.…
What Does High Neutrophils Mean?
High neutrophils (neutrophilia): above 7,000/µL. Usually indicates bacterial infection, inflammation, stress, or smoking.…
What Is Total Bilirubin in a Blood Test?
Total bilirubin (0.3-1.2 mg/dL) measures the yellow pigment from red cell breakdown. High bilirubin causes jaundice. Direct vs indirect help…
What Does Low Creatinine Mean?
Low creatinine (below 0.6 mg/dL) usually reflects low muscle mass, not kidney disease. Causes: elderly, malnutrition, pregnancy, liver disea…
What Does High Hemoglobin Mean?
High hemoglobin (above 17.5/15.5 g/dL) causes: dehydration, chronic lung disease, high altitude, smoking, polycythemia vera, testosterone us…
What Is a Comprehensive Health Panel?
A comprehensive health panel combines CBC + CMP + lipid panel + TSH — 40+ values screening for anemia, infection, diabetes, kidney, liver, t…