Common vitamin and mineral deficiency blood tests
| Nutrient | Test | Normal Range | Common deficiency symptoms |
|---|---|---|---|
| Vitamin D | 25-OH vitamin D | 30–100 ng/mL | Bone pain, fatigue, muscle weakness, frequent infections |
| Vitamin B12 | Serum B12 | 300–900 pg/mL | Fatigue, tingling, memory problems, anaemia |
| Folate (B9) | Serum folate | >3.0 ng/mL | Anaemia, neural tube defects in pregnancy, fatigue |
| Iron | Ferritin (best marker) | Men: 24–336; Women: 11–307 ng/mL | Fatigue, hair loss, pale skin, breathlessness |
| Magnesium | Serum Mg | 1.7–2.3 mg/dL | Muscle cramps, insomnia, anxiety |
| Calcium | Serum Ca | 8.5–10.5 mg/dL | Muscle spasms, bone pain (severe deficiency) |
| Zinc | Serum zinc | 70–120 mcg/dL | Poor wound healing, taste/smell loss, immune dysfunction |
| Vitamin A | Serum retinol | 30–65 mcg/dL | Night blindness, dry skin, frequent infections |
Who is at highest risk of vitamin deficiency?
| Group | Most common deficiencies |
|---|---|
| Vegetarians / vegans | B12, iron, zinc, omega-3, vitamin D |
| Elderly | B12, vitamin D, calcium, folate |
| Pregnant / breastfeeding women | Folate, iron, vitamin D, iodine, B12 |
| People with malabsorption (coeliac, Crohn) | Iron, B12, folate, vitamin D, calcium, zinc |
| Obese patients | Vitamin D (stored in fat, less available) |
| People on long-term PPIs (omeprazole) | B12, magnesium |
| People on metformin | B12 |
| Indoor workers / dark skin | Vitamin D |
Vitamin D deficiency — the most prevalent
Vitamin D deficiency affects an estimated 40% of people globally. Risk factors include limited sun exposure, indoor lifestyle, darker skin pigmentation, obesity and living at high latitudes. Levels below 20 ng/mL are considered deficient; below 10 ng/mL is severe deficiency requiring high-dose supplementation. Even people who eat well can be deficient as very few foods naturally contain significant vitamin D.
Vitamin B12 deficiency — often missed
B12 is found almost exclusively in animal products. Deficiency is particularly common in vegetarians, vegans and the elderly. It can take 3–5 years of inadequate intake for deficiency to develop as the body stores significant reserves. Symptoms — fatigue, tingling, memory problems — are often attributed to other causes. Severe B12 deficiency causes irreversible nerve damage if untreated. Metformin (a common diabetes drug) reduces B12 absorption and should be monitored annually.
Folate deficiency in pregnancy
Folate (vitamin B9) deficiency in the first 28 days of pregnancy — before most women know they are pregnant — significantly increases the risk of neural tube defects (spina bifida, anencephaly). All women planning pregnancy or of childbearing age are recommended to take 400 mcg folic acid daily. Women with a history of neural tube defect pregnancy need 5 mg daily.
Questions to ask your doctor
- Should I have a full nutritional panel?
- Do I need B12 injections or will oral supplements work?
- What dose of vitamin D should I take?
- If I am pregnant or planning pregnancy, do I need folic acid?
- Is my fatigue explained by vitamin deficiency?