Health Library / Blood tests
Vitamin D deficiency in Lucknow: why so many reports come back low
· 6 min read · Lucknow
It surprises people that vitamin D deficiency is widespread in a city that gets as much sun as Lucknow does. It is one of the most frequently low results on a routine panel, and the reasons are less about sunshine being available and more about how little of it actually reaches skin.
Indoor work, covered clothing, higher melanin, air quality, and sunscreen all reduce the amount of vitamin D the skin makes. Diet contributes very little in a largely vegetarian population, because the richest natural sources are oily fish.
What the test measures
The test to ask for is 25-hydroxy vitamin D, usually written 25(OH)D. It reflects your stores over recent weeks, which is what you want to know. A different form, 1,25-dihydroxy vitamin D, exists and is not the right test for ordinary deficiency — it is used in specific kidney and calcium disorders and can look normal even when stores are empty.
It does not need fasting, and it can be taken at any time of day.
Reading the number
Laboratories report 25(OH)D in ng/mL or nmol/L, and the commonly used bands in ng/mL are these. Your doctor will interpret them against your calcium, your symptoms and any bone or kidney issues rather than in isolation.
- Below 20 ng/mL — deficient
- 20 to 29 ng/mL — insufficient
- 30 ng/mL and above — generally considered sufficient
- Very high levels can cause harm, which is why unsupervised mega-dosing is a bad idea
Who is worth testing
Routine testing of everyone is not recommended, but there are groups where it changes management often enough to be worth doing.
- Persistent bone or muscle aches, or unexplained fatigue
- Older adults, and anyone who has had a fragility fracture
- Osteoporosis, or being on treatment for it
- Very limited sun exposure — largely indoor days, or fully covered clothing
- Malabsorption conditions such as coeliac disease or inflammatory bowel disease, and after bariatric surgery
- Chronic kidney or liver disease, on your doctor's advice
Correcting it, and re-testing sensibly
Correction is straightforward and inexpensive, and your doctor will choose a dose and schedule based on how low the level is. What is worth knowing as a patient is that it is not fast — stores take weeks to rebuild, which is why re-testing a fortnight later is usually wasted money.
A repeat is generally useful around eight to twelve weeks after starting treatment, or as your doctor advises. Vitamin D is also fat-soluble and stored, so more is genuinely not better; high-dose supplements taken without supervision can push calcium up and cause problems of their own.
This article is general health information, not a diagnosis or a treatment plan. Test results are read alongside your symptoms and history — please discuss yours with your doctor. See our disclaimer.
