Diagnosis of low vitamin D levels (deciding which patients to test)

Serum vitamin D levels should NOT be checked routinely

Testing of serum vitamin D levels in winter months (October to March) will result in naturally lower levels due to seasonal variation.

Levels should only be checked when a patient has symptoms that suggest rickets, osteomalacia, or symptomatic hypocalcaemia

Specific SYMPTOMS which may lead to testing of vitamin D levels if clinically appropriate

• Severe aching in bone and muscles
• Proximal muscle weakness making standing up and walking difficult and painful.
• Marked waddling gait
• In all other cases with risk factors for deficiency lifestyle advice should be provided.

Testing for vitamin D deficiency

Test for 25-hydroxyvitamin D (25-OHD) levels which represent serum concentration of vitamin D3.

Clinicians may also choose to test serum calcium, phosphate, alkaline phosphatase and parathyroid hormone levels (bone profile) when clinically appropriate.

Interpreting vitamin D levels

Treatment of symptomatic vitamin D deficiency in adults

The primary aim of treatment is to replenish vitamin D stores then continue with a lower maintenance dose of vitamin D.

Oral loading regimen of vitamin D3 (colecalciferol) up to a total of approximately 300,000 units vitamin D given either as weekly or daily split doses.

Followed with a maintenance dose of 800 to 2000 units of oral vitamin D3 (colecalciferol) daily or larger doses at less frequent intervals (over the counter)

Monitoring vitamin D levels during treatment

Vitamin D levels do not need to be checked routinely, and can take 3-6 months to reach a steady state after treatment has started.

Local specialists recommend re-checking vitamin D levels 6 months after a loading regimen of vitamin D has been given.

If levels are still sub-optimal, compliance with medication should be discussed. Alternatively, consider referral to an appropriate specialist.

Calcium levels should be checked 1 month after the final loading dose of vitamin D to detect patients with sub-clinical primary hyperparathyroidism.

Providing an oral loading regimen of vitamin D is unlikely to cause hypercalcaemia but if concerned, clinicians should consider checking calcium levels as they are a more appropriate indicator of toxic levels of vitamin D.

Where unexplained nausea and / or vomiting in a patient taking pharmacological doses of vitamin D consider checking calcium levels

Choice of vitamin D products

MHRA guidance advise that prescribers use licensed products wherever possible.

Table 1: Coventry and Warwickshire treatment guidelines, based on expert consensus:

Choice of vitamin D products

MHRA guidance advise that prescribers use licensed products wherever possible.