biomarker guides
49 articles in this field-note collection.
Cystatin C blood test: normal range, high results, eGFR
Cystatin C is a kidney filtration marker that muscle barely moves. What's normal, what a high result means, how it pairs with creatinine, and when it's urgent.
CK blood test: normal levels, high causes, and next steps
CK is a muscle enzyme. Here's what a normal level is, why a hard workout can push it into the thousands, how to read it with AST and ALT, and when it's urgent.
Cortisol test: normal levels, high and low causes
Cortisol runs on a daily clock. Here's a normal morning level, what high and low results usually mean, how to read it with ACTH, and when low is urgent.
Copper blood test: normal levels, high and low causes
Most copper in your blood rides on one protein. Here's the normal range, the optimal ladder, why copper runs high or low, and how to read it with zinc.
Chloride blood test: normal range, low and high causes
Chloride is sodium's salt partner. Here's the normal range, what low or high chloride usually means, how to read it with sodium and CO2, and when to act.
Ceruloplasmin test: normal range, low and high results
Ceruloplasmin carries most of your blood's copper. What a normal level is, what low and high results usually mean, and when to think of Wilson disease.
Troponin test: normal levels, high results, next steps
Troponin is the blood test for heart-muscle injury. Here's what's normal on each test, what a high result usually means, and when it's an emergency.
Calcium blood test: normal range, high and low causes
Blood calcium is tightly controlled. Here's the normal range, the usual reasons it runs high or low, how to read it with PTH and albumin, and when it's urgent.
C-peptide test: normal levels, high and low causes
C-peptide shows how much insulin your pancreas makes. Here's the normal range, what high and low results usually mean, and how to read it with blood sugar.
BUN blood test: normal levels, high causes, and next steps
BUN measures urea, the waste your liver makes from protein. Here's a normal level, why it runs high or low, and how to read it next to creatinine.
BNP and NT-proBNP: normal levels, high causes, next steps
BNP and NT-proBNP rise when the heart is strained. What's normal by age, what else raises them, how to read them with other tests, and when it's urgent.
Bilirubin blood test: normal levels and why it runs high
Bilirubin comes from old red blood cells. Normal levels, why it runs high (often Gilbert syndrome), how to read it next to ALT and ALP, and when it's urgent.
CO2 blood test (bicarbonate): normal range, low and high
The CO2 on your metabolic panel is bicarbonate. Here's the normal range, what low or high usually means, how to read it with chloride, and when it's urgent.
AMH blood test: normal levels by age and what they mean
AMH tracks how many eggs your ovaries have left. See normal levels by age, what low and high results usually mean, and what AMH predicts.
Anion gap blood test: normal range, high and low causes
The anion gap is a quick math check on your electrolytes. What's normal, why it runs high or low, how to read it with bicarbonate and albumin, and when to act.
Amylase blood test: normal range, high and low causes
Amylase is a starch-digesting enzyme from your pancreas and salivary glands. What's normal, why it runs high or low, and when a high result is urgent.
aPTT blood test: normal range, long and short results
aPTT times how fast your plasma clots. Here's the normal range, what a long or short result usually means, how to read it with PT, and when it's urgent.
Absolute neutrophil count (ANC): normal, low and high
ANC counts the infection-fighting neutrophils in your blood. The normal range, why it runs low or high, how to read it with your CBC, and when to act.
Absolute monocyte count: normal range, highs and lows
Monocytes are white blood cells that clean up and call in help. Here's a normal count, why it runs high or low, and when a result needs a closer look.
Absolute lymphocyte count: normal, low, high and optimal
Lymphocytes are your B, T and NK immune cells. Here's a normal absolute count, what a low or high result usually means, and when it needs a closer look.
Absolute eosinophil count (AEC): normal, high and low
Eosinophils are white cells tied to allergy and parasites. Here's a normal count, the usual causes of a high one, the optimal range, and when it's urgent.
Absolute basophil count: normal range, highs and lows
Basophils are the rarest white blood cell. Here's a normal basophil count, what a high or low result usually means, and when a high count needs a closer look.
White blood cell count: normal range, high and low causes
Your WBC counts the immune cells in your blood. Here's the normal and optimal range, why it runs high or low, how to read the differential, and when to act.
Hemoglobin and hematocrit: normal ranges and what they mean
Hemoglobin carries oxygen; hematocrit is the share of your blood that's red cells. Here's what's normal, what low or high usually means, and what's urgent.
Albumin blood test: normal range, low causes, optimal
Albumin is the main protein in your blood. Here's the normal range, what optimizers aim for, why it usually runs low, and how to read it with its neighbors.
ALP blood test: normal levels, high and low causes
ALP is an enzyme from your liver and bones. Here's a normal level, why it runs high or low, how GGT tells liver from bone, and when it's urgent.
ALT blood test: normal levels, high causes, and next steps
ALT is a liver enzyme. Here's what a normal level is, the most common reasons it runs high, how to read it with AST and ALP, and when a high result is urgent.
ApoB test: normal and optimal levels, and what high means
ApoB counts the particles that clog arteries. Here's a normal level, the optimal targets, why it can be high when LDL looks fine, and what moves it.
AST blood test: normal levels, high causes, and next steps
AST is an enzyme in liver, muscle and red blood cells. What a normal level is, why it runs high, how to read it with ALT and CK, and when it's urgent.
DHEA-S blood test: normal by age, high and low causes
DHEA-S is an adrenal hormone that falls with age. Here's the normal range by age and sex, what high and low levels usually mean, and when it's urgent.
eGFR and creatinine: normal ranges, low eGFR causes
eGFR shows how well your kidneys filter, and it's calculated from creatinine. What's normal, what a low eGFR usually means, and when it's urgent.
Estradiol blood test: normal levels, high and low causes
Estradiol (E2) is your main estrogen. See normal levels for men and women, what high or low results usually mean, and how to read E2 with FSH and LH.
Fasting glucose test: normal, optimal, and high levels
Fasting glucose shows how your body holds blood sugar overnight. Here's what's normal, what's optimal, why it runs high or low, and when a result is urgent.
Ferritin blood test: normal levels, low and high causes
Ferritin shows how full your iron stores are. Here's what's normal and optimal, why it runs low or high, how to read it with iron saturation, and when to act.
Free T3 test: normal range, optimal levels, high and low
Free T3 is the active thyroid hormone. Here's the normal and optimal range, what high or low usually means, and how to read it with TSH and free T4.
Free T4 blood test: normal range, high and low causes
Free T4 is the unbound thyroid hormone in your blood. Here's what a normal level is, what optimizers aim for, why it runs low or high, and when it's urgent.
A1C (HbA1c) test: normal, optimal and high levels
A1C shows your average blood sugar over about 3 months. Here's what's normal, what optimal looks like, why it runs high or low, and when to get care.
HDL cholesterol: normal levels, low and high causes
HDL is the "good" cholesterol. Here's what a normal level is, why it runs low, when a high HDL stops helping, and how to read it with triglycerides.
Homocysteine test: normal levels, high causes, next steps
Homocysteine is an amino acid that B vitamins and your kidneys clear. What is normal, what optimizers aim for, why it runs high, and how to read it with B12.
CRP and hs-CRP blood test: normal levels and high causes
CRP is your body's inflammation signal. Here's what a normal CRP and hs-CRP is, the common reasons it runs high, and when a high result needs care.
LDL cholesterol: normal and optimal levels, high causes
LDL carries cholesterol into artery walls. Here's what a normal and optimal LDL is, why it runs high, how to read it with ApoB and Lp(a), and when to act.
Lp(a) blood test: normal levels, high risk, next steps
Lp(a) is an inherited cholesterol particle. Here's a normal level, the optimal targets, what a high result means for heart risk, and how to read the units.
Omega-3 index: normal levels, targets, and what moves it
The omega-3 index is the share of EPA and DHA in your red blood cells. Here's what's typical, why 8% is the usual target, and what raises it.
RDW blood test: normal range, high causes, next steps
RDW measures how much your red blood cells vary in size. Here's what's normal, what a high RDW usually means, and how to read it with MCV and ferritin.
Testosterone test: normal levels, low T causes, next steps
What a normal testosterone level is for men and women, the optimal ranges people aim for, the most common causes of low T, and when a result is urgent.
Triglycerides: normal levels, high causes, and next steps
Triglycerides are the fat in your blood. Here's what a normal level is, why they run high, how to read them with HDL and LDL, and when a result is urgent.
TSH blood test: normal range, high and low causes
TSH is your pituitary's signal to your thyroid. Here's what a normal TSH is, what optimizers aim for, why it runs high or low, and when it's urgent.
Vitamin B12 test: what low, normal and high levels mean
Vitamin B12 keeps your nerves and red blood cells healthy. Here's a normal level, why it runs low, how MMA settles a borderline result, and when to act fast.
Vitamin D blood test: normal, optimal, low and high levels
Your vitamin D test measures 25-hydroxyvitamin D. What is normal, what optimizers aim for, why it runs low or high, and when a result is urgent.