Vitamin D (25-Hydroxy)
Vitamin D is a fat-soluble vitamin/hormone produced in the skin when exposed to sunlight (UVB rays). It can also be obtained from food and supplements. The liver converts it to 25-hydroxyvitamin D [25(OH)D], the form measured in blood tests. Vitamin D is essential for calcium absorption, bone health, immune function, and mood regulation. Deficiency is epidemic in India.
Reference Ranges
Male
30 – 100
ng/mL
Female
30 – 100
ng/mL
Child
30 – 100
ng/mL
Ages 1–18
Reference ranges may vary by laboratory. Always compare with the range printed on your lab report.
What Low Levels Mean
Vitamin D below 20 ng/mL is deficient; 20–29 is insufficient. Deficiency causes bone pain, muscle weakness, fatigue, depression, and increased fracture risk. Severe deficiency causes rickets in children and osteomalacia in adults. It also weakens immunity and is linked to autoimmune diseases, cardiovascular disease, and certain cancers.
What High Levels Mean
Vitamin D above 100 ng/mL (toxicity) causes high calcium levels (hypercalcemia), leading to nausea, vomiting, kidney stones, and kidney damage. Toxicity only occurs from excessive supplementation — never from sun exposure or food alone. The body regulates production from sunlight.
Frequently Asked Questions
Why is vitamin D deficiency so common in India?
Despite abundant sunlight, 70–90% of Indians are vitamin D deficient. Reasons include dark skin (melanin blocks UVB), indoor lifestyles, air pollution blocking UVB, traditional clothing covering skin, sunscreen use, and limited dietary sources (few foods naturally contain vitamin D).
How much vitamin D should I supplement?
For deficiency (<20 ng/mL), doctors typically prescribe 60,000 IU/week for 8 weeks, then 60,000 IU/month as maintenance. For insufficiency (20–29), 1000–2000 IU daily is common. Always test levels before and after supplementation. Take with a fatty meal for better absorption.
Can I get enough vitamin D from sunlight?
Theoretically yes — 15–20 minutes of midday sun on arms and legs produces about 10,000–20,000 IU. But in practice, factors like dark skin, latitude, season, air pollution, sunscreen, and clothing significantly reduce production. Most dermatologists recommend supplements rather than prolonged sun exposure.
This information is for educational purposes only and should not replace professional medical advice. Always consult your doctor for interpretation of your test results.
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