Blood Tests
How to interpret blood count and hormone panel results — reference ranges, clinical context and common reading mistakes.
4.5How to Read a Basic Blood Test Panel
CBC, lipid panel, glucose, TSH — how to read the results of a basic blood panel so you catch early signals of a problem before it becomes a disease.
4.6Lipid Panel
The lipid panel is one of the most important — and still one of the most frequently misread — preventive blood tests: 'total cholesterol' alone tells you less than the ratios between its fractions.
4.6Complete Blood Count (CBC)
The most commonly ordered laboratory test in the world — a seemingly simple printout hides information about immunity, oxygen transport, and blood clotting, if you know what to look for.
4.7Liver Panel (ALT, AST, GGT, Bilirubin)
Four entries on a lab printout — ALT, AST, GGT, and bilirubin — can reveal liver damage before any symptoms appear, as long as you know how to tell a hepatocellular pattern apart from a cholestatic one.
4.7Creatinine and eGFR (Estimated Glomerular Filtration Rate)
Creatinine alone tells you surprisingly little about kidney function — only converting it into eGFR using the CKD-EPI equation reveals how much filtration capacity actually remains.
4.6Electrolytes: Sodium, Potassium, and Chloride
Sodium, potassium, and chloride sound like a chemistry-class topic, but their blood levels determine how your heart, muscles, and kidneys function — and even a small deviation can be an urgent warning sign.
4.7TSH and Thyroid Hormones (fT3, fT4, anti-TPO)
TSH is the first-line test for evaluating thyroid function, but on its own it rarely gives the full picture — only together with fT4, fT3, and anti-TPO can it distinguish a temporary fluctuation from an actual disorder.
4.5Homocysteine
Homocysteine is an intermediate amino acid of methionine metabolism, linked for decades to cardiovascular and neurological risk — though how much lowering it actually reduces that risk remains a point of controversy in the literature.
4.6Uric Acid (Blood Test)
Uric acid is the end product of purine breakdown — its blood test helps assess the risk of gout and kidney stones, but a single result on its own neither confirms nor rules out disease.
4.6Apolipoprotein B (ApoB)
While a standard lipid panel measures the amount of cholesterol carried in your blood, apolipoprotein B measures something different — the number of particles themselves that can actually penetrate the artery wall. That distinction can matter when a standard lipid panel looks fine but cardiovascular risk remains elevated.
4.6Lipoprotein(a) [Lp(a)]
Unlike LDL or triglycerides, lipoprotein(a) levels are over 80–90% determined by genetics — diet and lifestyle have minimal effect on it. It's the one lipid marker worth testing once in a lifetime, not periodically.
4.5D-dimer
D-dimer is a breakdown product of a blood clot — a test with exceptionally high sensitivity for ruling out deep vein thrombosis and pulmonary embolism, but low specificity, so on its own it almost never confirms a diagnosis.
4.5ESR (Erythrocyte Sedimentation Rate)
One of the oldest laboratory tests — simple, cheap, and still useful in select situations, though in most cases it's been replaced by the faster and more specific CRP.
4.6Folate (Vitamin B9) Blood Test
Folate (vitamin B9) is essential for DNA synthesis and cell division, and its deficiency produces an anemia that's indistinguishable to the naked eye from vitamin B12 deficiency — which is why the two are almost always tested together, and interpreting the result alone can be less straightforward than it looks.
4.6Coagulation Panel — INR, aPTT, and Prothrombin Time (PT)
INR, aPTT, and prothrombin time don't detect the presence of a clot — they measure how efficiently blood can clot at all, evaluating two distinct arms of the coagulation cascade. This is a core panel before surgery, in unexplained bleeding, and for monitoring anticoagulant therapy, and interpreting it requires understanding which pathway each parameter tests.
4.5Total Protein and Albumin Blood Test
Total protein and albumin are among the oldest, yet also most ambiguous, laboratory panels — the same low result can mean malnutrition, kidney disease, chronic inflammation, or simply blood dilution from IV fluids, and telling these scenarios apart takes more than a single number on a printout.
4.6Calcium Blood Test (Total & Ionized)
Blood calcium is one of the body's most tightly regulated parameters — the total and ionized tests measure somewhat different things, and choosing the right one and interpreting it correctly determines whether an abnormality gets caught at all.
4.6Prolactin (Blood Test)
Prolactin is a pituitary hormone best known for its role in lactation, but an elevated level can also be the first sign of a pituitary tumor, hypothyroidism, medication side effects, or simply the stress of the blood draw itself.
4.6LH and FSH (Sex Hormones, Gonadotropins)
Luteinizing hormone (LH) and follicle-stimulating hormone (FSH) are pituitary gonadotropins that govern the ovaries and testes — interpreting them together helps determine whether a fertility or cycle problem lies in the gonads themselves or higher up, in the brain.
4.7Troponin and NT-proBNP (Cardiac Markers)
Cardiac troponin and NT-proBNP are two distinct, complementary blood biomarkers used in cardiology — the first detects ongoing damage to heart muscle cells, the second signals hemodynamic strain on the heart's ventricles. Together they play a key role in diagnosing acute coronary syndrome and heart failure, though an elevated result in either doesn't always mean a heart attack or heart failure.
4.6Creatine Kinase (CK/CPK)
Creatine kinase (CK, formerly CPK) is an enzyme released into the blood when muscle tissue — skeletal or cardiac — is damaged. It's ordered both in the diagnosis of muscle disease and in monitoring statin safety, as well as by athletes after intense training, where a moderately elevated result is a physiological phenomenon rather than a pathology.
4.5IGF-1 (Insulin-Like Growth Factor 1)
IGF-1 is a liver-produced protein made in response to growth hormone, and its stable serum concentration makes it a far more practical marker for assessing somatotropic axis function than measuring growth hormone itself. The test is used both to diagnose growth hormone deficiency and excess.
4.5Fibrinogen
Fibrinogen is a plasma protein that serves as the final substrate of the coagulation cascade and is also one of the main acute-phase inflammatory proteins — its concentration is assessed both in diagnosing clotting disorders and as an independent cardiovascular risk indicator. This test evaluates clotting function and inflammatory status, distinct from D-dimer, which detects an already-existing clot.