Clinical Reference Index
The graduated cutoffs behind each vital and lab value — where "normal" ends and where each next band begins.
< 120/80 mmHg
Systolic (top) < 120 mmHg; Diastolic (bottom) < 80 mmHg. Elevated: 120-129/<80. High Stage 1: 130-139/80-89. High Stage 2: ≥140/≥90. Hypertensive crisis: >180/>120. Measure after 5 min rest, no caffeine/smoking 30 min prior.
60-100 bpm
Beats per minute at rest. Athletes may have 40-60 bpm (normal for them). Bradycardia: <60 bpm. Tachycardia: >100 bpm. Best measured in the morning before getting up.
36.1-37.2 °C (97-99 °F)
Normal oral temperature. Low-grade fever: 37.3-38.0 °C. Fever: >38.0 °C. Hypothermia: <35.0 °C. Temperature varies slightly by time of day (lowest in morning, highest in afternoon).
12-20 breaths/min
Normal breaths per minute at rest in adults. Tachypnea: >20/min (may indicate infection, anxiety, or lung issues). Bradypnea: <12/min. Count for a full minute for accuracy.
95-100%
Measured by pulse oximeter on fingertip. 94% or below requires medical attention. Below 90% is a medical emergency. Values can be affected by nail polish, cold fingers, or poor circulation.
18.5-24.9 kg/m²
Calculated as weight(kg) / height(m)². Underweight: <18.5. Normal: 18.5-24.9. Overweight: 25-29.9. Obese Class I: 30-34.9. Obese Class II: 35-39.9. Obese Class III: ≥40. Note: BMI does not distinguish muscle from fat.
Men < 90 cm, Women < 80 cm
Measured at the midpoint between the lowest rib and the top of the hip bone. High risk for metabolic disease: Men ≥ 90 cm, Women ≥ 80 cm (Asian guidelines). Indicator of abdominal obesity and cardiovascular risk.
Men: 10-20%, Women: 18-28%
Proportion of fat to total body weight. Men: Essential fat 2-5%, Athletic 6-13%, Fitness 14-17%, Acceptable 18-24%, Obese >25%. Women: Essential 10-13%, Athletic 14-20%, Fitness 21-24%, Acceptable 25-31%, Obese >32%. Measured by DEXA, BIA, or skinfold calipers.
70-99 mg/dL (3.9-5.5 mmol/L)
Blood sugar after 8-12 hours of fasting. Pre-diabetes: 100-125 mg/dL. Diabetes: ≥126 mg/dL on two separate tests. Hypoglycemia: <70 mg/dL. Avoid eating or drinking (except water) before the test.
< 5.7% (< 39 mmol/mol)
Reflects average blood sugar over 2-3 months. Pre-diabetes: 5.7-6.4% (39-47 mmol/mol). Diabetes: ≥6.5% (≥48 mmol/mol). Target for diabetics under treatment: <7% (<53 mmol/mol). Not affected by recent meals.
< 140 mg/dL (< 7.8 mmol/L)
Blood glucose 2 hours after drinking 75g glucose solution. Impaired glucose tolerance (pre-diabetes): 140-199 mg/dL. Diabetes: ≥200 mg/dL. Used to diagnose diabetes and gestational diabetes. Also called Oral Glucose Tolerance Test (OGTT).
2-25 µIU/mL
Measures insulin resistance. High fasting insulin with normal glucose suggests early insulin resistance or pre-diabetes. Used to calculate HOMA-IR (insulin resistance score). Elevated in metabolic syndrome, PCOS, and obesity.
< 2.0
Calculated as (Fasting Glucose mg/dL × Fasting Insulin µIU/mL) / 405. Score <2.0: normal. 2.0-2.9: early insulin resistance. ≥3.0: significant insulin resistance. Useful for detecting metabolic syndrome before diabetes develops.
< 200 mg/dL (< 5.2 mmol/L)
Desirable: <200 mg/dL. Borderline high: 200-239 mg/dL. High: ≥240 mg/dL. Requires 9-12 hour fasting before test. High cholesterol increases risk of heart disease and stroke.
< 100 mg/dL (< 2.6 mmol/L)
Low-Density Lipoprotein. Optimal: <100 mg/dL. Near optimal: 100-129. Borderline high: 130-159. High: 160-189. Very high: ≥190 mg/dL. For patients with heart disease, target is <70 mg/dL.
Men ≥ 40 mg/dL, Women ≥ 50 mg/dL
High-Density Lipoprotein. Higher is better. Optimal: ≥60 mg/dL (protective against heart disease). Low HDL (<40 men, <50 women) is a cardiovascular risk factor. Exercise and healthy fats can raise HDL.
< 150 mg/dL (< 1.7 mmol/L)
Blood fats stored as energy. Borderline high: 150-199 mg/dL. High: 200-499 mg/dL. Very high: ≥500 mg/dL (risk of pancreatitis). Elevated by excess sugar, alcohol, refined carbs, and obesity. Requires fasting before test.
< 130 mg/dL
Total Cholesterol minus HDL; includes all atherogenic (artery-clogging) lipoproteins. Optimal: <130 mg/dL. Good predictor of cardiovascular risk, especially in people with high triglycerides. Calculated from standard lipid panel.
< 5.0 (Ideal < 3.5)
Cardiovascular risk ratio. Ideal: <3.5. Acceptable: <5.0. High risk: >5.0. Calculated by dividing total cholesterol by HDL. Lower ratio = better cardiovascular health. Doctors often use this as a quick risk estimator.
< 30 mg/dL (< 75 nmol/L)
Genetically determined cardiovascular risk marker. High Lp(a) (>50 mg/dL) is an independent risk factor for heart attack and stroke, even with normal LDL. Largely unaffected by diet or exercise. Checked once in a lifetime for family history screening.
Men: 13.5-17.5 g/dL, Women: 12-15.5 g/dL
Protein in red blood cells carrying oxygen. Low hemoglobin = anemia (fatigue, pallor, shortness of breath). High hemoglobin may indicate dehydration or polycythemia. Part of the Complete Blood Count (CBC) panel.
Men: 41-53%, Women: 36-46%
Percentage of red blood cells in total blood volume. Low = anemia or blood loss. High = dehydration or polycythemia vera. Closely related to hemoglobin levels.
Men: 4.5-5.9 million/µL, Women: 4.0-5.2 million/µL
Number of red blood cells per microliter. Low RBC = anemia. High RBC = polycythemia (dehydration, high altitude, or blood disorder). RBC, hemoglobin, and hematocrit together confirm anemia diagnosis.
80-100 fL
Average size of red blood cells. Low MCV (microcytic): iron deficiency anemia or thalassemia. High MCV (macrocytic): B12/folate deficiency, alcohol use, hypothyroidism. Normal MCV with low Hgb = normocytic anemia (chronic disease, blood loss).
27-33 pg
Average amount of hemoglobin per red blood cell. Low MCH (hypochromic) seen in iron deficiency. High MCH (hyperchromic) seen in B12/folate deficiency. Used alongside MCV to classify anemia type.
4,500-11,000 cells/µL
Measures immune cells. High WBC (leukocytosis) may indicate infection, inflammation, or leukemia. Low WBC (leukopenia) may indicate viral infection, autoimmune disease, or bone marrow problems. Part of CBC panel.
1,800-7,700 cells/µL (40-70% of WBC)
Primary immune cells that fight bacterial infections. High neutrophils: bacterial infection, stress, steroid use. Low neutrophils (neutropenia): viral infection, chemotherapy, autoimmune disease. Increased risk of infection when neutrophils <500.
1,000-4,800 cells/µL (20-40% of WBC)
Immune cells involved in viral defense and immunity (T cells, B cells). High lymphocytes: viral infection, chronic lymphocytic leukemia. Low lymphocytes: HIV, severe illness, steroid use. Lymphocyte count is important in HIV monitoring.
200-950 cells/µL (2-8% of WBC)
Immune cells that fight chronic infections and inflammation. High monocytes: chronic infection (TB), inflammatory conditions, or blood cancers. Monocytes transform into macrophages in tissues to engulf pathogens.
100-500 cells/µL (1-4% of WBC)
Immune cells involved in allergic responses and parasitic infections. High eosinophils (eosinophilia): allergies, asthma, parasitic infections, eczema, or drug reactions. Very high levels may indicate hypereosinophilic syndrome.
150,000-400,000 /µL
Cells that help blood clot. Low (thrombocytopenia): <150,000 — risk of excessive bleeding. High (thrombocytosis): >400,000 — risk of clotting. Dengue fever can cause rapid platelet drop. Critical: <20,000 is a bleeding emergency.
7.5-12.5 fL
Average size of platelets. High MPV with low platelet count suggests platelets are being consumed (immune destruction or clotting). Low MPV may indicate bone marrow suppression. Marker of platelet activity and cardiovascular risk.
0.5-2.5% of RBC
Immature red blood cells; indicates bone marrow activity. High reticulocytes: active RBC production (after blood loss or iron supplementation — good sign). Low reticulocytes with anemia: bone marrow not responding (aplastic anemia, B12/iron deficiency).
Men: 0.74-1.35 mg/dL, Women: 0.59-1.04 mg/dL
Waste product filtered by kidneys. Elevated creatinine indicates reduced kidney function. Used along with eGFR to assess kidney health. Dehydration and high meat intake can temporarily raise creatinine.
≥ 90 mL/min/1.73m²
Estimates how well kidneys filter waste. Stage 1 (normal): ≥90. Stage 2 (mild decrease): 60-89. Stage 3 (moderate): 30-59. Stage 4 (severe): 15-29. Stage 5 (kidney failure): <15. CKD is diagnosed if low for >3 months.
7-20 mg/dL
Measures kidney function and protein metabolism. High BUN may indicate kidney disease, dehydration, or high protein diet. Low BUN may indicate malnutrition or liver disease. BUN:Creatinine ratio also used diagnostically (normal 10-20:1).
Men: 3.4-7.0 mg/dL, Women: 2.4-6.0 mg/dL
Byproduct of purine metabolism. High uric acid (hyperuricemia): >7 mg/dL in men, >6 mg/dL in women — risk of gout and kidney stones. Caused by high purine foods (red meat, organ meats, shellfish, alcohol). Gout attacks occur in joints.
< 30 mg/g creatinine
Small amounts of albumin in urine; early marker of kidney damage. Microalbuminuria: 30-300 mg/g (early diabetic nephropathy or hypertension damage). Macroalbuminuria: >300 mg/g (established kidney disease). Key screening test for diabetics and hypertensives.
0.62-1.15 mg/L
Alternative kidney marker; more accurate than creatinine in early kidney disease, obesity, or low muscle mass. Not affected by diet or muscle mass. Used when creatinine-based eGFR may be unreliable (elderly, malnourished, athletes).
7-56 U/L
Liver enzyme. Elevated ALT is a key indicator of liver damage or inflammation (hepatitis, fatty liver, alcohol use). Mild elevations (<3x normal) may be non-specific. Very high elevations (>10x) suggest acute liver injury.
10-40 U/L
Found in liver, heart, and muscles. Elevated in liver disease, heart attack, or muscle injury. AST:ALT ratio >2:1 suggests alcoholic liver disease. Often checked together with ALT as liver function test.
44-147 U/L
Enzyme found in liver and bones. Elevated in liver disease (bile duct obstruction), bone disorders, or during growth in children/teens. High in pregnancy (placental source). Checked as part of liver function panel.
Men: 9-48 U/L, Women: 9-32 U/L
Liver enzyme sensitive to alcohol use and bile duct disease. Elevated in alcoholic liver disease, fatty liver, bile duct obstruction, and some medications. Often the first liver enzyme to rise with alcohol excess. Used alongside ALP and ALT.
0.1-1.2 mg/dL
Yellow pigment from red blood cell breakdown. High bilirubin causes jaundice (yellowing of skin/eyes). Direct bilirubin >0.3 suggests liver/bile duct issue. Indirect bilirubin >1.0 may indicate hemolysis or Gilbert's syndrome.
0.0-0.3 mg/dL
Bilirubin processed by the liver. Elevated direct bilirubin indicates hepatocellular disease or bile duct obstruction (gallstones, cholestasis, liver cirrhosis). If total bilirubin is high but direct is normal, suspect hemolysis or Gilbert's syndrome.
6.0-8.3 g/dL
Measures albumin and globulin in blood. Low total protein indicates malnutrition, liver disease, or kidney disease (protein loss). High levels may suggest dehydration or multiple myeloma.
3.5-5.0 g/dL
Main protein made by the liver; reflects nutritional status and liver function. Low albumin suggests malnutrition, liver cirrhosis, nephrotic syndrome, or chronic illness. Important marker of overall health status and liver synthetic function.
PT: 11-13.5 sec | INR: 0.8-1.1
Measures blood clotting ability and liver synthetic function. Elevated INR (>1.5) in non-anticoagulated patients suggests severe liver disease or vitamin K deficiency. Patients on warfarin (blood thinner) target INR 2.0-3.0. Critical: INR >4.0 is serious bleeding risk.
0.4-4.0 mIU/L
Primary screening test for thyroid function. High TSH: hypothyroidism (underactive thyroid — fatigue, weight gain, cold intolerance). Low TSH: hyperthyroidism (overactive thyroid — weight loss, rapid heartbeat, heat intolerance).
0.8-1.8 ng/dL
Active thyroid hormone. Checked when TSH is abnormal to confirm thyroid dysfunction. Low Free T4 + High TSH = Primary hypothyroidism. High Free T4 + Low TSH = Hyperthyroidism.
2.3-4.2 pg/mL
Most active form of thyroid hormone. Checked in suspected hyperthyroidism or to monitor thyroid treatment. High Free T3 with low TSH = T3 thyrotoxicosis. Low in hypothyroidism and non-thyroidal illness (sick euthyroid syndrome).
< 34 IU/mL
Autoantibodies against thyroid peroxidase enzyme. Elevated in Hashimoto's thyroiditis (most common cause of hypothyroidism) and Graves' disease. Positive result with normal TSH means higher lifetime risk of developing thyroid disease. Screened in thyroid symptoms or family history.
136-145 mEq/L
Main electrolyte controlling fluid balance. Hyponatremia (<136): symptoms include nausea, headache, confusion, seizures. Hypernatremia (>145): caused by dehydration or excess sodium. Critical for nerve and muscle function.
3.5-5.0 mEq/L
Electrolyte vital for heart and muscle function. Hypokalemia (<3.5): muscle weakness, cramps, arrhythmia. Hyperkalemia (>5.0): dangerous cardiac arrhythmias. Can be affected by kidney disease, diuretics, or ACE inhibitors.
8.5-10.2 mg/dL
Essential for bones, nerve signals, and muscle contraction. Hypocalcemia (<8.5): muscle cramps, tetany, osteoporosis risk. Hypercalcemia (>10.2): fatigue, kidney stones, confusion. Parathyroid and vitamin D regulate calcium.
1.7-2.4 mg/dL
Essential for 300+ enzyme reactions, muscle/nerve function, and energy. Hypomagnesemia (<1.7): muscle cramps, insomnia, anxiety, irregular heartbeat, migraines. Common in people with poor diet, diabetes, alcohol use, or on PPIs/diuretics. Often underdiagnosed.
2.5-4.5 mg/dL
Works with calcium for bone health and energy (ATP). Low phosphorus: malnutrition, refeeding syndrome, hyperparathyroidism. High phosphorus: kidney disease (cannot excrete it). Elevated phosphorus in CKD accelerates cardiovascular disease.
98-107 mEq/L
Electrolyte that maintains fluid balance and acid-base status. High chloride (hyperchloremia): metabolic acidosis, dehydration. Low chloride (hypochloremia): vomiting, metabolic alkalosis. Usually interpreted alongside sodium and bicarbonate (CO2).
22-29 mEq/L
Reflects acid-base balance in the body. Low bicarbonate: metabolic acidosis (kidney disease, diabetic ketoacidosis, diarrhea). High bicarbonate: metabolic alkalosis (vomiting, excess antacids, diuretics). Part of the basic metabolic panel (BMP).
30-100 ng/mL (75-250 nmol/L)
Essential for bone health, immune function, and mood. Deficient: <20 ng/mL. Insufficient: 20-29 ng/mL. Optimal: 30-60 ng/mL. Toxicity risk: >100 ng/mL. Very common deficiency, especially with limited sun exposure.
200-900 pg/mL
Essential for nerve function and red blood cell formation. Deficient: <200 pg/mL — causes anemia, numbness, memory issues. At-risk groups: vegetarians/vegans, elderly, those on metformin. Supplementation or injection may be needed.
2.7-17.0 ng/mL
Essential for DNA synthesis and red blood cell formation. Deficient: <2.7 ng/mL — causes megaloblastic anemia and neural tube defects in pregnancy. Critical for women planning pregnancy (supplement 400-800 mcg/day). Depleted by alcohol and some medications.
Men: 60-170 µg/dL, Women: 50-170 µg/dL
Measures iron in blood. Low iron suggests iron-deficiency anemia (fatigue, pallor). High iron may indicate hemochromatosis (iron overload, liver damage). Best interpreted with ferritin and TIBC.
Men: 20-500 ng/mL, Women: 20-200 ng/mL
Protein that stores iron; best indicator of iron stores. Low ferritin (<20): iron deficiency (even before anemia develops). High ferritin (>500): inflammation, liver disease, or hemochromatosis. Ferritin is an acute-phase reactant — can be falsely elevated during illness.
240-450 µg/dL
Measures the blood's capacity to bind iron with transferrin. High TIBC + low iron + low ferritin = iron deficiency anemia. Low TIBC + high iron = iron overload (hemochromatosis) or chronic disease. Used to differentiate types of anemia.
70-120 µg/dL
Essential mineral for immunity, wound healing, taste, and smell. Low zinc: frequent infections, poor wound healing, hair loss, loss of taste/smell. At-risk groups: vegetarians, elderly, those with malabsorption. Supplement with caution — excess zinc impairs copper absorption.
< 0.04 ng/mL (high-sensitivity: < 14 ng/L)
Protein released from damaged heart muscle. Primary blood test for heart attack diagnosis. Even slight elevation is significant. Rises within 2-4 hours of heart attack, peaks at 24 hours, remains elevated for 1-2 weeks. Also elevated in myocarditis, pulmonary embolism, and severe sepsis.
< 100 pg/mL
Hormone released by heart ventricles when under pressure/strain. Used to diagnose and monitor heart failure. BNP 100-400: possible heart failure. >400: likely heart failure. Also elevated in kidney disease, pulmonary hypertension, and valvular disease. NT-proBNP cutoff: <300 pg/mL.
5-15 µmol/L
Amino acid linked to cardiovascular disease risk. Elevated (>15): increases risk of heart attack, stroke, and blood clots. Associated with B6, B12, and folate deficiency. Supplements of these vitamins can lower homocysteine. Common in elderly and vegans.
< 90 mg/dL (< 80 for high-risk)
Protein on all atherogenic (artery-clogging) lipoprotein particles including LDL, VLDL, and Lp(a). Considered by many cardiologists as the best single predictor of cardiovascular risk. High ApoB even with 'normal' LDL suggests elevated particle number and risk. Emerging standard of care in lipid management.
< 1.0 mg/L
Marker of inflammation. Standard CRP <10 mg/L is typical. High-sensitivity CRP (hs-CRP): <1.0 low cardiovascular risk, 1-3 moderate, >3 high risk. Elevated in infection, autoimmune diseases, and chronic inflammation. Key component of cardiovascular risk assessment (JUPITER trial).
Men: 0-15 mm/hr, Women: 0-20 mm/hr
Non-specific marker of inflammation or infection. Elevated in inflammatory conditions, autoimmune diseases, infections, anemia, and cancers. Naturally increases with age. Must be interpreted alongside other tests.
T-score ≥ -1.0
Measures bone strength. Normal: T-score ≥ -1.0. Osteopenia (low bone mass): -1.0 to -2.5. Osteoporosis: ≤ -2.5 (high fracture risk). Z-score compares to age-matched peers. Recommended for women ≥65, men ≥70, or younger with risk factors.
15-65 pg/mL
Regulates calcium and phosphorus balance. High PTH (hyperparathyroidism): elevated blood calcium, kidney stones, bone loss. Low PTH (hypoparathyroidism): low calcium causing muscle spasms and tingling. Checked when calcium or vitamin D is abnormal.
Men: 12-52 ng/mL, Women (premenopause): 6-42 ng/mL
Protein produced by bone-forming cells (osteoblasts). Marker of bone formation rate. Elevated in conditions with high bone turnover (Paget's disease, hyperparathyroidism). Low in low bone turnover states. Used alongside other bone markers to monitor osteoporosis treatment.
6-23 µg/dL (measured 8 AM)
Stress hormone from adrenal glands; peaks in the morning. Low cortisol: adrenal insufficiency (Addison's disease — fatigue, low blood pressure, hypoglycemia). High cortisol: Cushing's syndrome (weight gain, moon face, high blood pressure). 24-hour urine or saliva test also used.
Men (20-29): 280-640 µg/dL | Women (20-29): 65-380 µg/dL
Adrenal hormone that declines with age. Low DHEA-S associated with fatigue, low libido, depression, and reduced muscle mass. Elevated in adrenal tumors or congenital adrenal hyperplasia (in women: acne, excess hair). Values decline ~20% per decade after age 30.
2-25 µIU/mL
Measures insulin resistance. High fasting insulin with normal glucose suggests early insulin resistance or pre-diabetes. Used to calculate HOMA-IR (insulin resistance score). Elevated in metabolic syndrome, PCOS, and obesity.
300-1,000 ng/dL
Primary male sex hormone. Low testosterone (hypogonadism): <300 ng/dL — causes fatigue, low libido, erectile dysfunction, muscle loss, depression. Measured in the morning (highest levels 8-10 AM). Declines ~1% per year after age 30. Confirmed with two morning tests.
50-210 pg/mL
Biologically active testosterone not bound to proteins. More accurately reflects testosterone available to tissues than total testosterone. Low free testosterone with normal total T suggests high SHBG (common in obesity, liver disease, aging). Calculated from total T, SHBG, and albumin.
Men: 10-57 nmol/L
Protein that binds testosterone, making it inactive. High SHBG lowers free testosterone availability (low libido, fatigue). Low SHBG increases free testosterone (linked to insulin resistance and metabolic syndrome). Elevated by aging, liver disease, thyroid disease.
< 4.0 ng/mL
Screening marker for prostate health (men only). <4.0: generally normal. 4-10: borderline, may need further evaluation. >10: higher risk of prostate cancer. PSA can also be elevated by BPH (benign enlargement) or prostatitis. Recommended screening for men >50 (or >40 with family history).
1.7-8.6 IU/L
Pituitary hormone that stimulates testosterone production. High LH + low testosterone = primary hypogonadism (testicular failure). Low LH + low testosterone = secondary hypogonadism (pituitary/hypothalamus problem). Used to find the cause of low testosterone.
Follicular: 12-166 pg/mL | Ovulation: 85-498 | Luteal: 43-228 | Postmenopause: <55
Primary female sex hormone. Low estradiol: menopause symptoms (hot flashes, vaginal dryness, mood changes, bone loss). High estradiol: estrogen dominance (breast tenderness, heavy periods, fibroids). Levels vary by cycle phase — specify day of cycle when testing.
Follicular: 0.1-0.9 ng/mL | Luteal: 1.8-24.0 ng/mL | Postmenopause: < 0.1
Hormone that prepares the uterus for pregnancy. Low progesterone in luteal phase suggests anovulation (no ovulation) or luteal phase defect. Key test for fertility evaluation. Measured on day 21-23 of a 28-day cycle.
Follicular: 2.5-10 IU/L | Ovulation: 3.4-33 | Luteal: 1.5-9.1 | Postmenopause: 23-116
Pituitary hormone stimulating egg development. High FSH (>10 in follicular phase): reduced ovarian reserve or approaching menopause. Very high FSH (>40) with low estrogen = menopause. Tested on day 2-3 of menstrual cycle for fertility evaluation.
Follicular: 1.9-12.5 IU/L | Ovulation surge: 8.7-76.3 | Luteal: 0.5-16.9
Triggers ovulation. LH surge (rapid rise) occurs ~24-36 hours before ovulation — used in ovulation predictor kits. High LH with high androgens suggests PCOS. High LH:FSH ratio (>2:1) is a classic PCOS finding. Used for fertility timing and cycle assessment.
1.0-3.5 ng/mL (age-dependent)
Best single marker of ovarian reserve (egg supply). Low AMH (<1.0): diminished ovarian reserve, reduced fertility. High AMH (>3.5): may indicate PCOS. Not affected by cycle phase — can be tested any day. Used for IVF planning, predicting menopause timing, and PCOS evaluation.
2-29 ng/mL (non-pregnant women)
Hormone that stimulates breast milk production. Elevated prolactin: irregular periods, infertility, galactorrhea (unexpected milk production), headaches. Common causes: pituitary adenoma (prolactinoma), hypothyroidism, antipsychotic medications, stress. Should be measured fasting in the morning.
15-70 ng/dL
Women also produce testosterone; important for libido and energy. High testosterone in women: PCOS, adrenal hyperplasia, ovarian tumor — causes acne, hirsutism (excess hair), irregular periods. Low testosterone: low libido, fatigue, poor muscle tone.
35-430 µg/dL (age 20-29)
Adrenal androgen precursor. Elevated in PCOS or adrenal hyperplasia — causes acne, excess hair growth, irregular periods. Used to distinguish ovarian vs adrenal source of androgen excess. Levels naturally decline with age.
4.5-8.0
Measures acidity of urine. Acidic urine (<5.5): high-protein diet, dehydration, kidney stones (uric acid type). Alkaline urine (>7.5): UTI (urease-producing bacteria), metabolic alkalosis, vegetarian diet. Normal average pH ~6.0.
Negative (< 150 mg/day)
Protein should not be significantly present in urine. Proteinuria indicates kidney disease, diabetic nephropathy, or hypertension. Persistent protein requires further kidney evaluation. Trace protein can be normal after exercise or standing (orthostatic proteinuria).
Negative
Glucose in urine (glucosuria) may indicate diabetes when blood glucose exceeds the renal threshold (~180 mg/dL). Can also occur in pregnancy or rare kidney conditions (Fanconi syndrome). Requires follow-up with fasting glucose or HbA1c.
0-2 RBC/HPF (Negative on dipstick)
Red blood cells in urine (hematuria). Visible blood: gross hematuria — urgent evaluation needed. Microscopic: >3 RBC/HPF on repeat testing requires workup (kidney stones, UTI, kidney disease, or bladder/kidney cancer). Menstrual contamination is common in women.
0-5 WBC/HPF
>5 WBC/HPF suggests urinary tract infection (UTI) or kidney inflammation (pyelonephritis, nephritis). With positive nitrites and leukocyte esterase on dipstick = strong indicator of bacterial UTI. Culture needed to identify the organism and sensitivity.
Negative
Produced when body burns fat for fuel. Positive ketones: diabetic ketoacidosis (DKA — dangerous), prolonged fasting, very low carb (keto) diet, or intense exercise. In diabetics with high blood sugar + positive ketones = emergency.
1.005-1.030
Measures urine concentration. Low (<1.005): overhydration, diabetes insipidus, kidney inability to concentrate urine. High (>1.030): dehydration, SIADH, heart failure. Ideal hydration: 1.010-1.020. Morning urine is normally more concentrated.
Men: 800-2,000 mg/day, Women: 600-1,800 mg/day
Used to assess completeness of 24-hour urine collections and as a reference for other urine measurements (e.g., albumin-to-creatinine ratio). Also used to calculate eGFR alongside serum creatinine.
< 4.0 ng/mL
Prostate cancer screening for men. Age-adjusted: <2.5 for men <50, <3.5 for 50-59, <4.0 for 60-69, <5.0 for ≥70. Rising PSA over time (PSA velocity) may be more significant than single value. Always interpreted with digital rectal exam and risk factors.
< 35 U/mL
Used to monitor ovarian cancer (women). Elevated in ovarian cancer but also in endometriosis, fibroids, pelvic infection, liver disease, and even menstruation. Not reliable enough as a standalone screening test. Useful for monitoring known ovarian cancer response to treatment.
Non-smokers: < 2.5 ng/mL, Smokers: < 5.0 ng/mL
Tumor marker used mainly to monitor colorectal cancer. Also elevated in breast, lung, pancreatic cancers. Not suitable for screening (can be elevated in smokers, IBD, liver disease). Used post-treatment to detect recurrence. Falling CEA after cancer treatment = good response.
< 10 ng/mL
Tumor marker for liver cancer (hepatocellular carcinoma) and testicular germ cell tumors. Elevated in liver cancer, cirrhosis, hepatitis. Also used to screen for liver cancer in high-risk patients (cirrhosis, chronic hepatitis B). Very high AFP (>400) strongly suggests HCC.
< 37 U/mL
Tumor marker associated with pancreatic, biliary, and gastrointestinal cancers. Used to monitor pancreatic cancer treatment and detect recurrence. Not a diagnostic test alone — can be elevated in benign conditions like pancreatitis, liver disease, and bile duct obstruction.
< 30 U/mL
Tumor marker used to monitor breast cancer treatment and recurrence — not for diagnosis or screening. Elevated in metastatic breast cancer. Can also be elevated in benign breast disease, liver disease, or other cancers. Falling CA 15-3 = positive response to breast cancer therapy.
Negative
Screening test for active Hepatitis B infection. Positive = current HBV infection (acute or chronic). Chronic if positive for >6 months. Hepatitis B can cause cirrhosis and liver cancer. Vaccination provides protection. Part of standard pre-employment and antenatal screening.
≥ 10 IU/L (protective)
Indicates immunity to Hepatitis B — either from vaccination or past infection recovery. <10 IU/L = not protected, may need booster vaccine. Checked to verify vaccination effectiveness or immune status. Protective level is ≥10 IU/L.
Negative
Screening test for Hepatitis C infection. Positive result requires confirmatory HCV RNA test to distinguish active infection from cleared past infection. Hepatitis C can cause chronic liver disease, cirrhosis, and liver cancer. Highly curable now with direct-acting antivirals (95%+ cure rate).
Non-reactive (Negative)
Screens for HIV-1/HIV-2 antibodies AND HIV p24 antigen. Detects infection within 18-45 days of exposure. Non-reactive = no HIV infection detected. Reactive = requires confirmatory Western blot. Recommended for all adults at least once; annually for high-risk individuals.
Non-reactive (Negative)
Screening tests for syphilis (Treponema pallidum). Reactive result requires confirmatory TPHA or FTA-ABS test. Syphilis is completely curable with penicillin. Part of standard STI, antenatal, and pre-marital screening panels. Titers (1:4, 1:8, etc.) used to monitor treatment response.
Negative
Detects dengue virus protein in the first 1-5 days of fever. Used for early dengue diagnosis (before antibodies develop). Positive = active dengue infection, requires monitoring of platelet count and hematocrit. Paired with dengue IgM/IgG antibody tests for complete evaluation.
Negative
Blood test for latent or active TB infection. Preferred over TB skin test (TST) — more specific, not affected by BCG vaccination. Positive = TB infection present (requires chest X-ray to distinguish latent from active TB). Used for healthcare workers, immigrants, and immunocompromised patients.
Negative (or titer < 1:40)
Screening test for autoimmune diseases. Positive ANA (≥1:80) suggests autoimmune activity — requires further testing (anti-dsDNA, anti-Sm, etc.) to diagnose specific conditions like lupus (SLE), Sjögren's, scleroderma, or mixed connective tissue disease. Weakly positive ANA can occur in healthy people.
< 14 IU/mL
Autoantibody associated with rheumatoid arthritis (RA). Elevated in 70-80% of RA patients. Also positive in Sjögren's syndrome, hepatitis C, and some healthy elderly individuals. Not specific — use anti-CCP antibody for more specific RA diagnosis. Negative RF does not rule out RA (seronegative RA).
< 20 U/mL
Highly specific antibody for Rheumatoid Arthritis (RA). More specific than RF (95% specificity). Can be positive years before symptoms appear. Positive anti-CCP predicts more severe, erosive RA. Used alongside RF and clinical examination for RA diagnosis.
< 30 IU/mL
Specific autoantibody for Systemic Lupus Erythematosus (SLE/Lupus). High anti-dsDNA with positive ANA is highly diagnostic of lupus. Titers correlate with disease activity — rising levels may predict lupus flares. Also monitored to assess treatment response.
C3: 90-180 mg/dL | C4: 16-47 mg/dL
Proteins of the immune complement system. Low C3 and C4 in active lupus (SLE) — immune complexes consume complement. Also low in hereditary complement deficiency. High complement levels seen in acute inflammation. Used to monitor lupus disease activity alongside anti-dsDNA.
Anti-TPO: < 34 IU/mL | Anti-TG: < 115 IU/mL
Autoantibodies attacking thyroid tissue. Elevated in Hashimoto's thyroiditis (hypothyroidism) and Graves' disease (hyperthyroidism). Anti-TPO is more sensitive. Positive antibodies with normal TSH = higher risk of future thyroid disease. Monitor TSH annually if positive.
Approximately 400-600 L/min (adult, varies by age/sex/height)
Measures how fast air can be exhaled; used to monitor asthma. Green zone (>80% personal best): good control. Yellow zone (50-79%): caution, adjust medication. Red zone (<50%): emergency, seek immediate care. Use a peak flow meter at home. Personal best established during asthma-free period.
≥ 80% of predicted
Volume of air exhaled forcefully in the first second; measured by spirometry. Reduced FEV1 suggests obstruction (asthma, COPD). FEV1/FVC ratio < 0.70 = obstructive pattern. Mild COPD: 70-79%. Moderate: 50-69%. Severe: 30-49%. Very severe: <30%.
≥ 80% of predicted
Total amount of air forcefully exhaled after maximum inhalation. Reduced FVC suggests restrictive lung disease (pulmonary fibrosis, scoliosis, obesity). Normal FEV1/FVC with low FVC = restrictive pattern. Normal FEV1/FVC: >70% in adults.
20/20 (6/6 metric)
Measures sharpness of vision at 20 feet. 20/40: minimum for legal driving in most countries. 20/200 or worse with correction = legal blindness (USA definition). Reduced acuity may indicate refractive errors (myopia, hyperopia), cataracts, macular degeneration, or other eye disease.
10-21 mmHg
Pressure inside the eye; elevated IOP is the primary risk factor for glaucoma. High IOP (>21 mmHg): risk of optic nerve damage and glaucoma. Normal IOP with optic nerve damage = Normal-Tension Glaucoma. Measured by tonometry during eye exams. Recommended every 2 years after age 40.
0-25 dB HL (Normal hearing threshold)
Measures the softest sounds heard across frequencies (250-8,000 Hz). Normal: 0-25 dB. Mild hearing loss: 26-40 dB. Moderate: 41-55 dB. Moderately severe: 56-70 dB. Severe: 71-90 dB. Profound: >90 dB. Hearing aids recommended when speech frequency loss exceeds 40 dB.
Negative
Detects hidden blood in stool — a key colorectal cancer screening tool. Positive result requires colonoscopy for evaluation. Blood can come from polyps, colorectal cancer, hemorrhoids, or IBD. Annual testing recommended for adults 45-75. Avoid red meat, NSAIDs, and vitamin C 3 days before test.
Negative
Detects Helicobacter pylori bacteria in stool. H. pylori causes most peptic ulcers and increases stomach cancer risk. More accurate than blood antibody test. Positive = active infection; treat with triple therapy antibiotics + PPI. Used for initial diagnosis and to confirm eradication after treatment.
< 50 µg/g
Marker of intestinal inflammation. Elevated (>200 µg/g) suggests active inflammatory bowel disease (Crohn's, ulcerative colitis). 50-200 µg/g: borderline, repeat in 4-6 weeks. Helps differentiate IBD (high calprotectin) from irritable bowel syndrome/IBS (normal calprotectin). Used to monitor IBD disease activity.
30-110 U/L
Enzyme produced by the pancreas and salivary glands. Elevated amylase (>3x normal) with abdominal pain: acute pancreatitis. Also elevated in salivary gland disease, kidney disease, bowel obstruction. Returns to normal faster than lipase (within 24-72 hours).
0-160 U/L
Pancreatic enzyme that digests fats. More specific than amylase for diagnosing acute pancreatitis. Elevated (>3x normal) is the gold standard for pancreatitis diagnosis. Remains elevated longer than amylase (up to 2 weeks). Also elevated in kidney disease and bowel obstruction.
30-80 µg/dL
Fat-soluble vitamin essential for vision, immune function, and skin. Deficiency: night blindness, dry eyes (xerophthalmia), frequent infections. At-risk: malabsorption syndromes, alcoholism, and children in developing countries. Toxicity possible with excess supplements — teratogenic in pregnancy.
0.6-2.0 mg/dL
Water-soluble antioxidant vitamin. Deficiency: scurvy (bleeding gums, joint pain, fatigue, poor wound healing). At-risk: smokers (require 35 mg/day more), poor diet, alcoholism. Excess intake (>2,000 mg/day) may cause kidney stones. Most people get adequate vitamin C from diet.
5.0-20.0 mg/L
Fat-soluble antioxidant. Deficiency (rare): nerve damage, muscle weakness, poor immune function. More commonly seen in fat malabsorption disorders. High-dose supplements may increase bleeding risk and interact with blood thinners. Adequate intake generally met through diet (nuts, seeds, vegetable oils).
70-140 µg/dL
Essential trace mineral for iron metabolism, nervous system, and collagen formation. Low copper: anemia unresponsive to iron, neurological symptoms (often from excess zinc supplementation). High copper: Wilson's disease (genetic copper accumulation), liver damage, psychiatric symptoms. Ceruloplasmin is also measured for Wilson's disease screening.