Almost everyone in the UK is advised to consider 10 micrograms of vitamin D a day between October and March. Testing is worth it where there are symptoms or risk factors rather than routinely. The Core panel including vitamin D, thyroid and ferritin is £350.
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Any of these needs to be seen the same day. If you are severely unwell, go to your nearest emergency department or call 999.
Vitamin D is made in the skin from sunlight and comes in small amounts from oily fish, eggs and fortified foods. It regulates calcium and phosphate, which is why severe deficiency affects bone and muscle rather than energy.Scientific Advisory Committee on Nutrition SACN report, 2016
Between October and March the UK sun is too weak to make any, whatever the weather. That is a fact about latitude rather than about lifestyle, and it is why the advice is seasonal.NICE PH56, 2017
Severe deficiency causes bone pain, muscle weakness and difficulty rising from a chair or climbing stairs. Mild deficiency usually causes nothing measurable, which is why the tiredness people attribute to it often has another cause.Scientific Advisory Committee on Nutrition SACN report, 2016
The groups at highest risk are people with darker skin, people who cover their skin, people who are housebound, and people who are pregnant or breastfeeding. Those are the groups where testing and treatment change something.NICE PH56, 2017
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The test measures 25 hydroxyvitamin D. It is worth doing where there are symptoms of deficiency, where somebody sits in a high risk group, or where bone health is already a question, and it is not recommended as a routine test in people with no symptoms.JAMA USPSTF, 2021
It goes in the same draw as thyroid, ferritin and calcium, because the symptoms people bring belong to those as often as to vitamin D and testing one alone leaves the answer half found.NICE PH56, 2017
Iron is the one most often behind it. Tiredness, poor concentration and hair shedding are all produced by low stores, and a ferritin taken at the same time is what settles which of the two you are dealing with.Gut Snook, 2021
What a result will and will not change is said before the sample is taken. Where the answer is to supplement either way, that is the honest reason not to run the test.General Medical Council GMC guidance, 2020
A daily supplement through the winter
10 micrograms a day between October and March is the standing UK advice for the whole population, and it is bought over the counter for a few pounds a year.Scientific Advisory Committee on Nutrition SACN report, 2016
A daily supplement all year
For people with darker skin, who cover their skin, or who are rarely outdoors. The reason is exposure rather than diet, and it does not change with the season.NICE PH56, 2017
A treatment course for measured deficiency
Higher doses for a fixed period followed by a maintenance dose, with calcium checked. It is prescribed against a measurement rather than against a symptom.Scientific Advisory Committee on Nutrition SACN report, 2016
Doing nothing beyond the standing advice
The right answer for most adults with no symptoms and no risk factors. The population advice already covers you and a test would not change it.JAMA USPSTF, 2021
A treatment course raises the level over 8 to 12 weeks and a repeat test before then measures the treatment rather than the person. Muscle symptoms from genuine deficiency improve over weeks to months rather than days.Scientific Advisory Committee on Nutrition SACN report, 2016
The inconvenient half, and it is a large one. A meta analysis of 81 randomised trials found vitamin D supplementation did not reduce fractures or falls, and had no clinically meaningful effect on bone mineral density. A large randomised trial also found no reduction in cancer or cardiovascular events. It corrects a deficiency and it is not a preventive medicine.The Lancet Diabetes and Endocrinology Bolland, 2018
What the large prevention trial did show is worth stating alongside. Supplementation did not lower the rate of invasive cancer or major cardiovascular events over more than 5 years, which is the strongest evidence available and it is negative.New England Journal of Medicine Manson, 2019
Take 10 micrograms a day from October to March, whatever your result. That is the standing UK advice for everybody over 4, it costs a few pounds a year, and it does not require a test or an appointment to act on.Scientific Advisory Committee on Nutrition SACN report, 2016
Before blaming vitamin D for tiredness, check the other three. Ferritin, thyroid and a full blood count explain far more fatigue than vitamin D does, and they come in the same draw for the same fee.NICE PH56, 2017
Stop any high dose supplement 1 week before testing if you want to know your baseline. A level measured during a loading course tells you about the course rather than about you.JAMA USPSTF, 2021
Do not buy a standalone vitamin D test if you have no symptoms and no risk factors. The population advice is to supplement anyway, so a result would not change what you do, and the test costs more than a year of the supplement.JAMA USPSTF, 2021
Do not buy high dose intermittent injections or megadose supplements to prevent fractures or falls. The trials do not support it and very high intermittent dosing has been associated with more falls rather than fewer.The Lancet Diabetes and Endocrinology Bolland, 2018
Do not buy repeat testing every few months while on a stable dose. Once the level is corrected, an annual check is the most that is useful and for many people even that is not.Scientific Advisory Committee on Nutrition SACN report, 2016
Step 1
Symptoms, skin, exposure and risk group. Where the answer is that you should supplement either way, that is said rather than sold around.
Step 2
Vitamin D alongside thyroid, ferritin, calcium and liver function in one draw, because the symptoms belong to those as often as to this.
Step 3
A course where the level is properly low, a repeat at 8 to 12 weeks, then maintenance. No repeat testing every few months.
Ask before you book if you are not sure this is the right appointment.
Almost everybody in the UK is advised to consider 10 micrograms a day between October and March, because the sun is too weak to make any at this latitude in those months. People with darker skin, who cover up or are rarely outdoors are advised to take it all year.
Only if you have symptoms of deficiency, sit in a high risk group, or have a bone health question. Routine testing in people with no symptoms is not recommended, largely because the advice to supplement applies either way.
The evidence says no. A meta analysis of 81 randomised trials found no reduction in fractures or falls and no clinically meaningful effect on bone density. It corrects a deficiency, which matters, and it is not a preventive medicine for the general population.
Sometimes, where the deficiency is genuine and severe. Mild deficiency usually causes nothing measurable, and ferritin, thyroid and a full blood count explain far more fatigue. All four come in the same draw, which is why they are done together.
The Core panel including vitamin D, thyroid, ferritin, calcium, lipids and HbA1c is £350 and a doctor reads it with you. The Advanced panel with hormones and full thyroid is £650. The result explained by telephone is £59.
Eight to 12 weeks on a treatment course, and a repeat test sooner than that measures the treatment rather than you. Muscle symptoms from genuine deficiency improve over weeks to months rather than within days.
Yes. Very high doses raise calcium and cause thirst, confusion, nausea and kidney problems, and intermittent megadosing has been associated with more falls rather than fewer. That is why a treatment course is prescribed against a measurement and has an end date.
This page is general information about a condition and it is not a diagnosis. Treatment depends on what a doctor finds when they examine you, and no outcome is guaranteed. If you are severely unwell, or if any of the warnings at the top of this page apply to you, go to your nearest emergency department or call 999.
General Medical Council
Decision making and consentGMC guidance, 2020
Gut, British Society of Gastroenterology
Guidelines for the management of iron deficiency anaemia in adultsSnook, 2021
JAMA, United States Preventive Services Task Force
Screening for vitamin D deficiency in adults, recommendation statementUSPSTF, 2021
New England Journal of Medicine
Vitamin D supplements and prevention of cancer and cardiovascular disease, VITALManson, 2019
NICE
Vitamin D, supplement use in specific population groupsPH56, 2017
Scientific Advisory Committee on Nutrition
Vitamin D and healthSACN report, 2016
The Lancet Diabetes and Endocrinology
Written by the clinical team at The Wellness. Awaiting clinical sign off.
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