lab-guides

High-sensitivity C-reactive protein is a non-specific marker of systemic inflammation. Chronically elevated values track with cardiovascular and metabolic risk. Optimal below 1.0 mg/L.

Serum B12 alone misses functional deficiency. Pairing it with methylmalonic acid (MMA) catches tissue-level shortfall — critical for vegans, metformin users, and older adults.

TSH measures pituitary signalling; Free T3 and T4 measure the thyroid hormones themselves. The combined panel separates primary thyroid disease from pituitary or conversion issues.

Glycated haemoglobin gives a 12-week glucose average that cannot be gamed. The pre-diabetic band (5.7–6.4%) is fully reversible — but only if caught. Completes the metabolic trio with fasting glucose and insulin.

The most commonly deficient nutrient in northern-latitude adults. Optimal range 40–60 ng/mL — most labs report 'normal' at 20+. What moves it and why toxicity is real above 100 ng/mL.

RBC folate reflects long-term folate status better than serum folate. Required for methylation, DNA synthesis, and homocysteine clearance.

Fibrinogen is a clotting factor and acute-phase reactant. Chronically elevated values track with cardiovascular and stroke risk. Use alongside hs-CRP.

Ferritin reflects the body iron storage. Low ferritin precedes anaemia and shows up first as fatigue, brittle hair, restless legs, or breathlessness on exertion.

Fasting insulin and the derived HOMA-IR score reveal insulin resistance years before fasting glucose drifts up — the earliest commonly available metabolic marker.

Plasma glucose measured after an 8–12 hour fast. The simplest standalone metabolic marker, available on every basic panel.

Estradiol is the primary oestrogen of the reproductive years. Levels vary across the cycle; perimenopause shows wide swings. Interpret with cycle day or status.

DHEA-S is the most abundant circulating steroid hormone. It declines after age 30; low values for age track with stress load, under-recovery, and aging.