Download Clinical Practice Assessment Screening for Vitamin D Deficiency

Clinical Practice Assessment
Screening for Vitamin D Deficiency
Clinical Question:
In what clinical setting is screening for 25- OH Vitamin D deficiency useful?
Bottom Line:
Screening for Vitamin D deficiency is not recommended. Measuring 25-OH Vitamin D levels is only
necessary in the evaluation of suspected disorders of calcium regulation or metabolic bone disease.
In other patients supplementation with Vitamin D at a dose of 1000 IU daily can be offered without a
need for measuring 25-OH Vitamin D levels. The risk of hypercalcaemia with supplementation at this
level is insignificant.
Synopsis:
Recently many widespread health benefits have been associated with Vitamin D supplementation.
Profound deficiency causes osteomalacia with the associated clinical findings of deep proximal bone
pain, weakness and fractures. Meta-analysis studies have shown Vit D supplementation of 400-7001000 IU reduces the incidence of falls and mortality. Similar Vitamin D doses with calcium
supplementation reduces fracture incidence. Less certain associations with Vitamin D include
decreased risks of cardiovascular disease, diabetes and even cancer. It remains unclear as to the
association of other clinic finding to Vitamin D deficiency or the benefits of treatment beyond that of
1000 IU per day. There is no accepted or recommended reason for measuring 25-OH Vitamin D
based on clinical symptoms.
Vitamin D deficiency (measured by serum 25-OH Vitamin D levels) leads to secondary
hyperparathyroidism and bone loss. Vitamin D supplementation has been shown to decrease plasma
levels of parathyroid hormone (PTH), to temper the elevations of bone turnover markers and increase
bone mineral density. The 25-OH Vitamin D level needed to prevent secondary hyperparathyroidism
has been estimated to be between 10ng/ml to 50ng/ml and is generally accepted above 20ng/ml. In
those with osteoporosis, supplementation of Vitamin D with calciferol should be given if a 25-OH Vit
D level < 20ng/ml with a goal of maintaining the level above 32ng/ml. One can expect a 20ng/ml level
to increase to 32ng/ml with 1700 IU of Vitamin D a day.
Conditions associated with low Vitamin D levels include: malabsorption, osteoporosis, chronic renal
disease, drugs including phenytoin, phenobarbitol, carbamazepine, isoniazide, theophyline, rifampin,
antiretroviral agents and glucocorticoids.
In evaluating patients with disorders of calcium regulation, osteoporosis (meaning a high fragility
fracture risk) or those who on bone density have a Z-score of < -2.0, measuring a 25-OH Vitamin D
levels is indicated. Vitamin D deficiency with secondary hyperparathyroidism is common and
replacement along with a total calcium intake of 1000-1200mg/day total lowers the incidence of future
fractures. Unless the history or exam suggests the possibility of other medical issues being present
the evaluation for causes of osteoporosis beyond a 25-OH Vitamin D level needs to only include a
complete chemistry panel, TSH, PTH and a 24-hour urine for calcium.
Treatment options;
 Forms of inactive Vitamin D (calciferol):
o Cholecalciferol Vitamin D3 synthesized in the skin by sunlight UVB
o Erogocalciferol Vit D2 present in plants and some fish
o Vitamin D3 may be up to 3x more potent than Vit D2
o Available strengths of Vitamin D3 include 400, 1000, 2000, 5000 and 50,000 IU tabs
 Effectiveness of Vitamin D supplementation:
o 1000 IU=25ug of Vitamin D which typically increases the serum 25-OH level by 7 ng/ml
o 25-OHD ng/ml x 2.50 converts to nmol/l. 20ng/ml=50nmol/l
Sources;
1. Bjorkman M. Responses of PTH to Vitamin D supplementation: A systemic review of clinical trials.
Arch Geront Geriat 2009; 48:160.
2. Semba RD. Relationship of 25-OHD with all-cause and CV disease mortality in older communitydwelling adults. Europ J Clin Nut 2009; doi:10.1038/ejcn.2009.140.
3. Bischoff-Ferrare H. Vit D: What is an adequate Vit D level and how much supplementation is
necessary. Best Pract Resear Clin Rheum 2009; 23:789.
4. Kanekar A. Vit D deficiency: A clinical spectrum: Is there a symptomatic nonosteomalacic state?
Int J of Endoc 2010. doi:10.1155/2010/521457.
5. Kulie T. Vit d: An evidence-based review. JABFM 2009; 22: 698.
6. Plotnikoff GA. Prevalence of severe hypovitaminosis D in patients with persistent, nonspecific
musculoskeletal pain. Mayo Clin Proc 2003; 78:1463.
7. Bjorkman M. Vit D supplementation has no major effect on pain or pain behavior in bedridden
geriatric patients with advanced dementia. Aging Clin Exp Res 2008; 20:316.
8. Bischoff-Ferrari HA. Prevention of nonvertebral fractures with oral vitamin D and dose
dependency: a meta-analysis of randomized controlled trials. Arch Intern Med. 2009 Mar 23;
169(6):551-61.
9. Bischoff-Ferrari HA. Fall prevention with supplemental and active forms of vitamin D: a metaanalysis of randomized controlled trials. BMJ. 2009 Oct 1; 339:b3692. doi: 10.1136/bmj.b3692.
10. Autier P. Vitamin D supplementation and total mortality: a meta-analysis of randomized controlled
trials. Arch Intern Med. 2007; 10:1709-10.
11. Abrahamsen B. Patient level pooled analysis of 68,500 patients from seven major vitamin D
fractures trails in US and Europe. BMJ 2010; 340:5463.
Originated: 4/20/11