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Vitamin blood test: when microdeficiency becomes a big problem
Vitamins are not supplements, but keys to cellular metabolism
Vitamin deficiencies have long been considered an extreme condition, the result of starvation or serious illness. However, modern laboratory medicine is increasingly detecting chronic microdeficiencies, which do not appear immediately, but over time affect the nervous system, heart, skin, reproductive function.
Blood test for vitamins — this is not a «fashion test», but part of a deep metabolic screening, which allows you to assess how the body is provided with necessary compounds under stress, diets, medications, or chronic conditions.
What vitamins can be checked in a blood test?
| Vitamin | Role in the body | Optimal level* |
|---|---|---|
| Vitamin D (25(OH)D) | Immunity, calcium metabolism, mood | 30–50 ng/ml |
| Vitamin B12 | Nervous system, hematopoiesis, energy | 200–900 pg/mL |
| Folic acid (B9) | DNA synthesis, pregnancy, cell division | >3 ng/ml |
| Vitamin A | Vision, skin, antioxidant protection | 0.3–0.7 mg/l |
| Vitamin E | Cell protection, cardiovascular system | 5–20 mg/l |
| Vitamin K1 | Blood clotting, calcium metabolism | 0.1–2.2 ng/ml |
| Vitamin C | Immunity, collagen, antioxidant | 0.4–2.0 mg/dL |
*Reference values may vary depending on the laboratory and patient condition.
Why is it important to check your vitamin status?
Most vitamins are not synthesized in the body or are synthesized in insufficient quantities. Even a complete diet does not guarantee proper absorption, if there is:
malabsorption syndrome;
diseases of the liver, pancreas, gastrointestinal tract;
vegetarian or ketogenic diet;
long-term medication (antacids, hormones, statins);
pregnancy or lactation;
growing body (children, adolescents);
recovery period after illness, surgery, COVID-19.
What should you know before taking the test?
Blood is taken in the morning, on an empty stomach, preferably after 8 hours without food.
3–5 days before the analysis it is worth stop taking vitamin supplements, unless contraindicated.
Upon delivery vitamin D In winter, be sure to report any medications you are taking.
Some vitamins (e.g., B9, B12, D) is worth passing in the complex with biochemical markers (homocysteine, calcium, ferritin) for correct interpretation.
When does a doctor order a blood test for vitamins?
Frequent colds, prolonged recovery from illnesses;
Sleep disturbances, mood swings, irritability;
Chronic fatigue syndrome;
Decreased memory and concentration;
Hair loss, brittle nails;
Infertility or preparation for pregnancy;
Suspicion of hypovitaminosis or hypervitaminosis.
Can hypervitaminosis be detected?
Yes, especially when uncontrolled intake of fat-soluble vitamins (A, D, E, K). That is why laboratory diagnostics is not only about identifying deficiencies, but also prevention of excess, which sometimes has a toxic effect.
How often should you check your vitamins?
Once a year — in the absence of symptoms, as part of a comprehensive examination.
Every 3–6 months — if you are already receiving vitamin therapy or have chronic conditions (diabetes, gastrointestinal diseases, immunodeficiencies).
A blood test for vitamins is a tool for personalized medicine. It helps detect the problem before symptoms appear, avoid unwanted consequences of self-medication and choose optimal dose of nutrients for a specific person. This is not fashion - this is biochemical literacy.
