Who needs a vitamin D test?
This test is not recommended for everyone. Who is more at risk of deficiency, and what is the danger of too many supplements?
Vitamin D helps the body absorb calcium and keeps bones and teeth healthy, and muscles, nerves and the immune system need it too. The body makes it in sunlight, and a few foods such as egg yolks, liver and fatty fish contain small amounts.
Who has the test?
Routine vitamin D testing is not recommended for everyone. A doctor usually asks for it with:
- Soft or thin bones, or fractures
- Bone pain, or muscle weakness or aches
- Little sun on the skin
- Malnutrition or weight-loss surgery
- Conditions that affect absorption, such as Crohn’s disease, ulcerative colitis and coeliac disease
- Kidney or liver disease
- Some medicines, including certain statins, steroids and weight-loss medicines
If you take supplements for a deficiency, the test may be repeated to see the trend.
How is it done?
Blood is taken from a vein in the arm, and most tests measure 25(OH)D. No special preparation is needed.
Too much is also a problem
Taking high doses of supplements for a long time can raise the calcium in your blood. This may weaken bones and damage the kidneys and heart. Nausea and vomiting, poor appetite, constipation, muscle weakness and weight loss can be signs of too much vitamin D.
So unless your doctor has written a specific dose for you, do not take high-dose supplements. Your doctor sets the dose and length of treatment from your result and your situation.
The doctor's own advice on supplement doses and when to repeat the test will be added once confirmed.