Sunlight

Please refer to the NICE guidance on sunlight exposure (NG34, February 2016).

From March to October ultraviolet B (UVB) rays help people produce vitamin D, but excessive exposure can also cause sunburn. Solar UV levels are highest during the summer (and most intense in late June). People who choose to expose their skin to strong sunlight to increase their vitamin D status should be aware that prolonged exposure (for example, leading to burning or tanning) is unlikely to provide additional benefit.

NHS Choices recommends that most people can make enough vitamin D from being out in the sun daily for short periods with their forearms, hands or lower legs uncovered and without sunscreen from March to October, especially from 11am to 3pm. About 10 to 15 minutes is enough for most lighter-skinned people. People with darker skin will need to spend longer in the sun to produce the same amount of vitamin D.

People should get to know their own skin to understand how long they can spend outside before risking sunburn under different conditions.

Diet

Dietary sources of vitamin D are limited. Dietary sources of vitamin D are natural foods, fortified foods and supplements. Natural food sources are very limited and are mostly of animal origin (such as oily fish, red meat and egg yolk). Fortified foods include: formula milks for infants and toddlers, some breakfast cereals and fat spreads (margarines). Some (but not all) brands of malted milk drinks contain added vitamin D.

Multivitamin preparations which contain vitamin D are available over-the-counter from pharmacies and supermarkets.

The Department of Health has produced guidance on identifying and managing people at risk of vitamin D deficiency.

The following groups of people are at risk of vitamin D deficiency:

• Pregnant and breastfeeding women especially teenagers and young women
• Infants and young children under 5 years of age
• Older people aged over 65 years
• People who are institutionalised or housebound, and those who cover their skin for cultural reasons
• People who have darker skin for example people of African, African-Caribbean and South Asian origin

Medical risk factors for deficiency include:

• Obesity (BMI over 30kg/m²)
• Chronic kidney disease
• Hepatic impairment
• Malabsorption syndromes or short bowel syndrome
• Some drug treatments (e.g. antiepileptic drugs, glucocorticoids, rifampicin, cholestyramine)

Patients at risk of vitamin D deficiency should be given advice on sun exposure and dietary sources of vitamin D (see above).Additional information regarding supplementation is provided below.

Pregnancy and lactation

All pregnant and breastfeeding women, especially teenagers and young women, are at risk of vitamin D deficiency. The Department of Health advises that these women should take a 10 microgram (400 units) vitamin D supplement each day to ensure the mother's requirements for vitamin D are met and to build adequate foetal stores for early infancy.

Women considered to be at high-risk (for example those with increased skin pigmentation, reduced exposure to sunlight, or those who are socially excluded or obese) may be advised to take higher doses of vitamin D. Specialist advice should be sought in these cases.

Pregnant women may be advised that multivitamin preparations are available over-the-counter which contain vitamin D and folic acid, however they should seek advice from their pharmacist, GP or midwife that the preparation does not contain vitamin A, as large amounts may harm an unborn baby.

Information is not provided in the formulary in relation to correction of vitamin D deficiency during pregnancy – consult local specialists for advice.

Infants and young children

The Department of Health advises that all infants and young children aged up to 5 years should take a daily supplement containing vitamin D in the form of vitamin drops.

• Infants from birth to one year of age, whether exclusively or partially breastfed, should be given a daily supplement containing 8.5 to10 micrograms vitamin D to make sure they get enough.
• Those infants who are fed infant formula will not need vitamin drops until they are receiving less than 500ml of infant formula a day, as these products are fortified with vitamin D.
• Children aged 1 to 4 years of age should be given a daily supplement containing 10 micrograms vitamin D.

Vitamin supplements can be purchased over the counter in pharmacies and supermarkets. Women and children from families who are eligible for the Government's Healthy Start scheme can get free vitamin supplements which include vitamin D, in the form of tablets for women and drops for children. Further information can be found on the Healthy Start website: www.healthystart.nhs.uk

Chronic kidney disease (CKD)

CKD is a risk factor for developing vitamin D deficiency.

Do not routinely offer vitamin D supplementation to prevent CKD–mineral and bone disorders.

Patients with significant renal impairment (eGFR less than 45ml/min/1.73m²) may have impaired renal hydroxylation function and may require an activated vitamin D derivative. If vitamin D deficiency has been corrected and features of CKD-mineral and bone disorders persist, alfacalcidol or calcitriol may be offered but with guidance from specialist services.

Some patients with significant renal impairment may benefit from treatment with both colecalciferol/ergocalciferol in combination with an activated vitamin D derivative (alfacalcidol or calcitriol); this requires specialist initiation.

Activated vitamin D derivatives:

• Alfacalcidol (see section 9.6 Vitamins)
• Calcitriol (see section 9.6 Vitamins)

Serum calcium and phosphate concentrations should be monitored in patients receiving alfacalcidol or calcitriol. Please see section 9.6 Vitamins, for further details regarding monitoring.

It is recommended to treat patients suspected of vitamin D deficiency empirically. This recommendation is made after due consideration of the drug cost compared to vitamin D laboratory test costs, and the negligible risk of vitamin D3 toxicity at advised doses.

There is no definitive national guidance about who should routinely have vitamin D levels measured but it may be considered in these groups:

• Patients with possible osteomalacia or rickets
• Proximal muscle weakness
• Persistent hypo or hypercalcaemia (based on corrected calcium level)
• Newly diagnosed osteoporosis (if considered appropriate by secondary care specialists)
• Conditions associated with malabsorption (secondary care initiated only)

Testing is not routinely indicated in conditions such as fibromyalgia or multiple sclerosis as despite vitamin D deficiency being linked with these conditions, causation is not proven.

Routine Vitamin D testing should not be necessary for patients with osteoporosis or fragility fractures who are co-prescribed vitamin D with an oral bisphosphonate.

Should testing be required, vitamin D status is currently best assessed by measurement of serum 25OHD.

Locally recognised results (T&SDFT, RD&E and NDDH) are in agreement with the Royal Society of Osteoporosis guidelines (2020):

• Deficiency: less than 25nmol/L (T&SDFT, RD&E and NDDH)
• Insufficiency: 25-50nmol/L (T&SDFT, RD&E and NDDH)
• Adequacy/sufficiency: greater than 50nmol/L (T&SDFT, RD&E and NDDH)

Before acting on a blood test result, consult specialist if a patient has primary hyperparathyroidism, renal insufficiency, or hypo or hypercalcaemia.

It is recommended to treat patients suspected of vitamin D deficiency empirically. This recommendation is made after due consideration of the drug cost compared to vitamin D laboratory test costs, and the negligible risk of vitamin D3 toxicity at advised doses.

If testing is performed, deficiency is noted to be recognised locally as a serum 25OHD level of less than 25nmol/L (T&SDFT, RD&E and NDDH).

Serum calcium levels should be tested before starting a calcium-containing product or treatment dose vitamin D. Specialist advice should be sought before starting patients with granulomatous disease, tuberculosis or active sarcoidosis on vitamin D therapy due to the risk of hypercalcaemia with high doses of vitamin D.

All patients should be provided advice on sun exposure and dietary sources of vitamin D (although it should be noted that only a small amount of vitamin D comes from the diet).

Patients with vitamin D deficiency may require loading treatment with pharmacological strength vitamin D3 (colecalciferol); the decision to prescribe such a regime should be based on the serum 25OHD level and the broader clinical picture. A loading regimen may be particularly important for patients with symptomatic disease or those who are about to start treatment with a potent antiresorptive agent.

Loading regimes with colecalciferol may be split over 6-8 weeks (depending on the patient and consideration of product licensing), providing a total dose of approximately 300,000 units. Faster loading may be recommended by hospital bone health specialists under certain circumstances.

Formulary preparations recommended for vitamin D loading over 6-8 weeks:

• Colecalciferol (Vitamin D3) tablets or oral solution (see section 9.6 Vitamins for dose information)

A solid dosage form is suitable for the majority of the population who require vitamin D loading; a small number may require a liquid alternative.

The use of annual depot vitamin D therapy (intramuscular or oral) and the use of activated vitamin D preparations (calcitriol and alfacalcidol) have been demonstrated not to work or to have a high risk of being ineffective or causing toxicity, and are therefore not recommended for the management of vitamin D deficiency. For details on the use of activated vitamin D in CKD patients please go to the section of guidance for individuals at risk of vitamin D deficiency.

Following correction of vitamin D deficiency, consider regular maintenance treatment with a vitamin D and calcium preparation, or vitamin D monotherapy:

• If the patient is already prescribed a calcium and vitamin D combination product (at least 1g calcium / 800 units (20 micrograms) vitamin D daily), continue and ensure compliance.
• If not already on calcium and vitamin D, advise patient to buy an OTC preparation containing 20 –25 micrograms (800–1000 units) of vitamin D per day, to be taken continuously or if buying supplements would be a barrier, a prescription may be issued at the prescriber's discretion:
  • Prescribe colecalciferol monotherapy for daily use or
  • Prescribe a combination product of colecalciferol plus calcium (at least 1g calcium /800 units (20 micrograms) colecalciferol daily) only if calcium supplementation needed.

It is important to promote the relevance of adequate dietary calcium intake. The National Osteoporosis Society recommend that if patients with osteoporosis are found to not be reliably or regularly consuming at least 700 mg calcium per day, titrated supplementation with either calcium-only supplements or calcium and vitamin D combined supplements is recommended.

Routine monitoring of serum 25OHD is generally unnecessary but may be appropriate in patients with symptomatic vitamin D deficiency or malabsorption and where poor compliance with medication is suspected. In most situations where retesting is considered appropriate, a minimum re-test interval of 3-6 months is recommended as studies suggest this is the time taken to reach a new steady-state of 25OHD, however if absorption is in doubt testing may be sooner.

Specialist advice should be sought regarding the follow-up of patients with hyperparathyroidism, renal insufficiency, malabsorption, hypo or hypercalcaemia or bariatric surgery.

Adjusted serum calcium should be checked 1 month after completing vitamin D loading regimen in case primary hyperparathyroidism has been unmasked.

If testing is performed, insufficiency is noted to be recognised locally as a serum 25OHD level of 25-50nmol/L (T&SDFT, RD&E and NDDH).

The treatment of vitamin D insufficiency is a grey area and advice on supplementation will depend upon the level within the range, the season and the likelihood of other sources of vitamin D being effective.

• Provide patient with advice on sun exposure and dietary sources of vitamin D (although it should be noted that only a small amount of vitamin D comes from the diet).
• If already on calcium and vitamin D (at least 1g calcium / 800 units (20 micrograms) vitamin D daily) continue and ensure compliance.

If not already on calcium and vitamin D, advise patient to buy an OTC preparation containing 20-25 micrograms (800–1000 units) of vitamin D per day, to be taken continuously, or if buying supplements would be a barrier, a prescription may be issued at the prescriber's discretion:

1. Prescribe colecalciferol monotherapy or
2. Prescribe a combination product of colecalciferol plus calcium (at least 1g calcium /800 units (20 micrograms) colecalciferol daily) only if calcium supplementation needed.

It is important to promote the relevance of adequate dietary calcium intake. The National Osteoporosis Society recommend that if patients with osteoporosis are found to not be reliably or regularly consuming at least 700 mg calcium per day, titrated supplementation with either calcium-only supplements or calcium and vitamin D combined supplements is recommended.

If a patient is symptomatic after 12 months consider retesting 25OHD level or treating with pharmacological strength vitamin D.

Serum calcium levels should be tested before starting a calcium-containing product or treatment dose vitamin D. Specialist advice should be sought before starting patients with granulomatous disease, tuberculosis or active sarcoidosis on vitamin D therapy due to the risk of hypercalcaemia with high doses of vitamin D.

If testing is performed, sufficiency is noted to be recognised as a serum 25OHD level greater than 50nmol/L (T&SDFT, RD&E and NDDH). This is a level which is considered adequate for the majority of the population.

Patients 65 years or older and those not exposed to regular daylight, should be given diet and sun exposure advice (although it should be noted that only a small amount of vitamin D comes from the diet). Consideration should be given to the individual patient risks, diet and sunlight exposure, before recommending a daily supplement containing 10 micrograms of vitamin D to this population. A variety of supplements containing 10 micrograms of vitamin D are available for purchase over the counter.

Patients under 65 years and exposed to regular daylight do not require supplementation; provide dietary information and sun exposure advice (although it should be noted that only a small amount of vitamin D comes from the diet).