5 Blood-Work Markers Every Adult Should Know (And What Yours Mean)

You don't need a 100-marker panel. These 5 catch most of the preventable problems early, are cheap (~$30 total), and don't require a doctor's referral at most labs.

1. Vitamin D (25-hydroxyvitamin D)

Optimal: 40–80 ng/mL. Below 30 = deficient. Below 20 = severe deficiency.

Why it matters: bone health, immune function, mood, muscle strength. Most adults globally are deficient because skin pigment + sunscreen + indoor work all reduce D synthesis.

Fix: 2,000 IU/day vitamin D3 supplement if below 40. Re-test in 8 weeks.

2. Ferritin

Optimal: 50–200 ng/mL (men), 30–150 (women).

Why it matters: ferritin is your iron storage. Low ferritin = fatigue, hair loss, exercise intolerance, cold hands/feet — even with normal hemoglobin. Common in pre-menopausal women and vegetarians.

Fix: iron-rich foods (red meat, dark leafy greens, lentils with vitamin C), or iron supplement if <30. Don't supplement without testing — too much iron is also harmful.

3. HbA1c

Normal: <5.7%. Pre-diabetic: 5.7–6.4%. Diabetic: ≥6.5%.

Why it matters: HbA1c measures average blood sugar over 3 months. Catches pre-diabetes years before any symptom shows. Critical given the global rise in metabolic disease.

Fix: lose weight (the strongest lever), reduce refined carbs, walk after meals, build muscle.

4. TSH (thyroid stimulating hormone)

Optimal: 0.5–2.5 mIU/L. Reference often 0.4–4.5.

Why it matters: thyroid drives metabolism. Subclinical hypothyroidism (TSH 2.5–4.5) is associated with fatigue, weight gain, and slow metabolism. Often missed by doctors who only flag values >4.5.

If high: check free T4 and TPO antibodies. See an endocrinologist.

5. Lipid panel

Includes total cholesterol, LDL, HDL, triglycerides.

LDL: <100 mg/dL ideal, <70 if family heart disease.
HDL: >40 men, >50 women.
Triglycerides: <150.
Triglyceride/HDL ratio: <2 is excellent. >3.5 = insulin resistance signal.

How often to test

Marker	Frequency
Vitamin D	Annually, more if supplementing
Ferritin	Annually, more if low
HbA1c	Annually after 30, every 6 months if pre-diabetic
TSH	Every 2–3 years if normal
Lipid panel	Annually after 30

How Zafit helps

Snap a photo of your lab report inside Zafit. Every marker gets explained, flagged, and tied to a concrete next action in your daily plan. No more "ask your doctor" non-answers.

Frequently asked

Can I order these tests without a doctor?

Most major diagnostic chains worldwide let you order direct. Total cost ~$30 for all five.

Should I fast for blood work?

Yes, ideally 10–12 hours, especially for the lipid panel and HbA1c.

My doctor said my numbers are 'normal' — should I worry?

'Normal' often just means 'inside the wide reference range.' Optimal ranges (above) are tighter. Push for explanation.