A vitamin D test measures 25-hydroxy vitamin D (25-OH D) in your blood, the best indicator of your body’s vitamin D stores. It checks for deficiency, which affects bones, muscles and immunity. A level of 30–100 ng/mL is generally considered sufficient, 20–29 ng/mL insufficient, and below 20 ng/mL deficient.
What does the vitamin D test measure?
Vitamin D helps your body absorb calcium and keeps bones and muscles strong. Your skin makes it from sunlight, and small amounts come from food such as egg yolks, oily fish and fortified milk.
The test measures 25-hydroxy vitamin D, the form your liver produces and stores. It stays in the blood for weeks, so it reflects your overall stores rather than yesterday’s sunlight.
Despite plentiful sunshine, vitamin D deficiency is very common in India. Office jobs, commuting in closed vehicles, sunscreen, covered clothing, air pollution, darker skin (which makes vitamin D more slowly) and vegetarian diets all contribute. Many people with low levels have no symptoms at all; others notice:
- Persistent tiredness and low energy
- Bone or lower-back pain, and muscle aches or weakness
- Frequent infections
- Low mood
Long-term deficiency weakens bones and raises the risk of osteoporosis and fractures later in life.
Vitamin D normal range
(below 50 nmol/L)
(50–74 nmol/L)
(75–250 nmol/L)
Where does your result fall?
Enter your 25-OH vitamin D value from your report.
A general guide, not a diagnosis. The reference range on your own report takes priority, and a doctor should interpret any result outside it.
These are the categories most Indian labs print, based on the 2011 Endocrine Society guideline. Expert bodies differ: some treat 20 ng/mL as adequate for bone health, so your doctor’s interpretation matters. To convert, ng/mL × 2.5 = nmol/L. Ranges vary between labs and methods. Always compare your result with the reference range printed on your own report.
What abnormal results can mean
- Low levels: Most often due to limited sun exposure or diet; can also follow gut absorption problems, liver or kidney disease, or some medicines.
- Very high levels: Almost always from taking too many supplements. This can raise blood calcium and needs a doctor’s review.
Do not start high-dose supplements on your own; dose depends on your level and should be set by a doctor.
Who should get this test?
- Office workers and people who spend little time outdoors.
- People with symptoms such as bone pain, muscle weakness or long-lasting fatigue.
- Women over 40, older adults, and anyone with osteoporosis or past fractures.
- People with obesity, gut conditions (such as coeliac disease) or kidney or liver disease.
- People taking vitamin D supplements, to check the dose is working, usually after about 3 months.
- Preparation: No fasting needed.
This page is for general information and is not a substitute for medical advice. Always interpret your results with a qualified doctor.