Vitamin D is made in sunlight, yet many of us run low.
Vitamin D is made in the skin when sunlight falls on it; a little comes from food. The body needs it to take up calcium from food and build strong bones, and it helps the muscles work. Low vitamin D is very common in India, sunshine and all, because many of us spend the day indoors or with most of our skin covered.
In plain words.
Who runs low: people who work indoors or cover most of their skin, older people, people carrying extra weight, pregnant and breastfeeding women, babies who are only breastfed, and people with kidney or liver disease, or bowel problems that stop food being absorbed. Some medicines lower it too, such as certain fit (epilepsy) medicines and long courses of steroids.
What it does: often nothing you can feel. When it stays low for long, the bones soften and ache, most often in the lower back, hips, legs and ribs, and the thigh muscles weaken, so stairs and getting up from the floor become hard. Over the years it adds to bone thinning and fractures. In children it causes rickets: bowed legs, slow growth and late walking.
Treatment is simple, but the dose matters. A doctor usually prescribes a stronger course for some weeks, then a smaller dose to keep the level up, and checks it again after about three months. Calcium from milk, curd and paneer, and some time in the sun on the face and arms without burning, help too. Too much vitamin D is harmful: it raises the calcium in the blood.
From sunlight to bone
Sunlight on the skin makes vitamin D. Once the liver and kidneys switch it on, it opens the gut’s door for calcium from food, and the calcium is laid down as a dense lattice inside the bones.
With little sun, little vitamin D is made. The door stays mostly shut, much of the calcium in food passes by, and the lattice inside the bone thins and softens. Bones ache and the thigh muscles tire.
Go to hospital now if
- Cramps with tingling around the mouth or in the fingers, or hands locking into spasm: go to hospital now. The calcium in the blood may be very low.
- A fit (seizure) at any age, or a baby with twitching, spasms or noisy, crowing breathing: call 112.
- While taking vitamin D: vomiting that will not stop, great thirst, passing a lot of urine, confusion or severe weakness: go to hospital now. Too much vitamin D may have raised the calcium.
- After a minor fall: severe pain in the hip or back, or you cannot stand or put weight on the leg: go to hospital now. A bone may be broken.
Call 112 or go to the nearest emergency department. Ambulance: 108 (102 in some states).
See a doctor within a week if
- Bone pain or weakness in the thighs is getting worse
- You have taken high-dose vitamin D for more than three months without a check or a plan
- A child has bowed legs, is growing slowly or is late to walk
- You have kidney disease, kidney stones or high calcium in the past, and want to start vitamin D
- A bone has broken after a minor fall, to look for thin bones
Tests that help.
Not everyone needs every test. He decides which ones are worth doing for you.
| Test | What it tells |
|---|---|
| 25-hydroxy vitamin D (25-OH D) | The test that shows your vitamin D stores. Below about 20 ng/mL is usually counted as deficient and 20 to 30 as low; labs differ slightly. Other vitamin D tests are rarely needed. |
| Calcium and phosphorus | Low values support the diagnosis. A high calcium is a reason not to take vitamin D until the cause is found. |
| Alkaline phosphatase (ALP) | Often raised when bones are softening. It is also part of the liver tests. |
| Creatinine (kidney test) | The kidneys switch vitamin D on; weak kidneys change how it is treated. |
| PTH (parathyroid hormone) | Sometimes checked when calcium is too high or too low, to find the reason. |
| Bone density scan (DEXA) | Done in person, for older people or after a break from a minor fall, to look for thin bones. |
Have it ready.
Tick them off as you gather them. The ticks stay on this phone only.
Online, or in person?
Vitamin D is safe at the right dose and harmful in excess. Many people take 60,000-unit capsules every week for months or years without a plan; this can raise the calcium and cause kidney stones or kidney damage. Take a strong course only as prescribed, and check the level when advised. Babies are usually advised 400 units of vitamin D drops a day in the first year; give any higher dose only as a doctor advises.
A video call can
Needs a visit in person
- A bone density scan
- Examining the bones and muscles when weakness is severe
- X-rays after a fall
- An injection, if a doctor decides tablets cannot be absorbed
- Any sign in the red box: that is an emergency
Talk it through with Dr. Arya.
Bring your reports and medicines to a video consultation. He goes through them with you, in plain words, and says clearly if you need to be seen in person.
Book a video consultationDr. Prabhat Arya · MBBS, MD (Internal Medicine) · Delhi Medical Council Reg. No. DMC-83759