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Vitamin D guidelines

Risk factors for Vitamin D deficiency
Aging : Reduced synthesis in the skin
Season : Reduced exposure to UV radiation October-April
LatitudeReduced exposure to UV radiation
Sunblock use : Reduced exposure to UV radiation
Clothing :  Reduced exposure to UV radiation
Institutionalization : Reduced exposure to UV radiation
Skin pigmentation :  Absorption of UV radiation by melanin
Malabsorption : e.g. pancreatic insufficiency, inflammatory bowel disease, coeliac disease, bariatric surgery, medications such as cholestyramine and orlistat
Obesity :  Sequestration of Vitamin D in fat
Drugs :  Induced metabolism of Vitamin D to inactive calcitroic acid e.g. rifampicin, phenytoin, glucocorticoids, HAART for HIV, transplant medications
Severe liver failure :  Failure to 25-hydroxylate vitamin D
Nephrotic syndrome :  Loss of Vitamin D in urine
Chronic kidney disease :  Hyperphosphataemia suppresses 1-hydroxylation
Definitions There are two different assays currently being used in ICHNT. The CXH assay is based on LC/MS-MS and the levels are not comparable to commonly quoted values in the literature. The SMH assay is based on an immunoassay and the levels are comparable to commonly quoted values in the literature.


25 hydroxy vitamin D Level (nmol/L)

CX                 SMH




<40            <25

Replace vitamin D: prescribe loading dose



40-69          25-50

Consider referral to secondary care and vitamin D replacement if:

  • Patient is taking glucocorticoids.
  • Patient is osteoporotic or osteopenic.
  • There is evidence of secondary hyperparathyroidism (normal calcium, PTH above reference range).
  • The calcium is below normal reference range.
  • There is chronic kidney disease stage 3/4 (KD-OQI guidelines).
  • If vitamin D replacement is required: prescribe maintenance dose (cholecalciferol 1000-2000 iu per day or 20000 iu per fortnight)


70-150        >50

Does not need replacement or continue present replacement dose.


Possibly toxic


Check calcium: needs to be referred to hospital if hypercalcaemic. Consider referring sample to different laboratory as there may be sample interference.


Loading dose over 3 months:

Prescribe colecalciferol (Dekristol) 20,000 IU capsules, one capsule weekly for 12 weeks, then go on to maintenance dose.

Consider giving IM ergocalciferol 300,000 IU two injections spaced by 3 months if there are concerns regarding absorption (e.g. in malabsorption).

Maintenance dose:

Usually between 1000-2000 IU colecalciferol per day depending on weight, e.g. Holland and Barrett Vitamin D3 25 microgram tablets, 1-2 tablets a day, or colecalciferol (Dekristol) 20,000 IU capsules, one capsule every 2 weeks.

Higher doses may be required e.g. if the patient is taking drugs that accelerate Vitamin D metabolism or if there are concerns regarding absorption.

Maintenance should be continued so long as risk factors for Vitamin D deficiency are present.

Notes on dosing:
Note: If the patient is hypercalcaemic they should be referred to the local Endocrinology service for further evaluation.
This guideline advocates the use of D3 or D2 for supplementation, not ‘active vitamin D’ (e.g. alfacalcidol, calcitriol) as the latter are more prone to the side effect of hypercalcaemia.

D3 is generally preferred as D2 may be less potent than D3, unit for unit.

If the patient is being given supplementation for osteoporosis and osteopenia, they should also receive 1000 mg of supplemental calcium daily, as calcium and vitamin D supplementation is effective in reducing the risk of hip fracture.

Vitamin D alone is not effective in reducing hip fractures.

Calcium supplements alone appear to be associated with a higher risk of heart attack and stroke and are therefore not recommended.

Pregnant and lactating women should be given calcium and 400 IU Vitamin D daily.

Up to 10000 IU per day is not toxic when given for up to 5 months.


Measure 25-hydroxyvitamin D, PTH, calcium after 3 months and 6-monthly thereafter to ensure that hypercalcaemia does not occur.

Aim for 25-hydroxyvitamin D 'replete' level, with calcium and PTH levels within reference ranges.

If in doubt, please refer to secondary care for advice.

Stop the supplementation if hypercalcaemia or kidney stones occur or if 25 hydroxyvitamin D level is above the replete reference range.

Prices of vitamin D:Vitamin D costs 2014

Prescribable Options (for reference)

Calcium & D3 supplements

  • Adcal D3 (chewable tablets)
    400 UNITS colecalciferol & calcium 600 mg per tablet. Two tablets daily (i.e. 800 UNITS D3).
  • Adcal D3 Dissolve
    400 UNITS colecalciferol & calcium 600 mg per tablet. Two tablets daily (i.e. 800 units D3).
  • Calcichew D3 Forte (chewable tablets)
    400 UNITS colecalciferol & calcium 500 mg per tablet. Two tablets daily (i.e. 800 UNITS D3).
  • Cacit D3 (effervescent powder)
    440 UNITS colecalciferol & calcium 500 mg per tablet. Two sachets daily (i.e. 880 UNITS D3).
    Note: contains cyclamate, saccharin.

Ergocalciferol (D2)

  • Intramuscular injection. 300,000 IU/ml. Either 300,000 IU per 3 months or 600,000 IU per 6 months.

Colecalciferol (D3)

  • Biovitamin D3 (pharma Nord). 1,000, 5,000 and 20,000 unit capsules available. Kosher and Halal.
  • Dekristol capsules. 20,000 IU capsules. One capsule every 1-2 weeks or see loading dose. Not Halal.
  • Intramuscular injection. 300,000 IU ampoule. One ampoule intramuscularly every 6 months.
  • 50,000 IU capsules. One capsule every 4 weeks.
  • Licenced vitamin D: there is no evidence that licenced vitamin D is any more effective that the preparations available over the counter. Licenced vitamin D is approximately 900% more expensive than the non-licenced equivalents.

Over the Counter Options (for reference) 

Printable vitamin D patient information sheet
There are many more OTC options than those listed. This list is not considered an endorsement of the specific supplements cited but purely reflects the fact that these are generally available locally from pharmacists and health food shops.
  • Biovitamin D3 (Pharma Nord) (see prescription list above: also available OTC. Kosher and Halal.
  • Vitabiotics Osteocare® Original tablets
    200 UNITS D3, magnesium 300 mg, calcium 800 mg, 0.6 mg B per tablet. Take 2 tablets daily (i.e. 400 UNITS D3).
  • Solgar® Vitamin D3
    Available as 1000 UNITS tablets or 2200 UNITS capsules (amongst other preparations).
    Note that 2200 UNITS capsules are vegetable-based formulations, Kosher and considered Halal. but not vegan as the source is lanolin (wool fat).
  • Boots High Strength Vitamin D®
    500 UNITS D3 per capsule. Not Kosher or Halal.
  • Holland and Barrett “Sunvite”® Vitamin D3
    Available as 25 micrograms D3 (1000 UNITS) tablets. Not Kosher or Halal.
  • Vitabiotics Ultra-D3®
    Available as a 25 microgram (1000 UNITS) tablet.
Cod liver oil capsules typically contain 200 IU per capsule but contain too much Vitamin A to be used as the sole source of vitamin D.
Similarly multivitamins generally contain too little vitamin D in relation to other vitamins to be used as the sole source of vitamin D.