Background: There has been increasing awareness of Vitamin D deficiency, but lack of clear guidelines for the optimum doses of Vitamin D in deficient states. The inadvertent use of higher doses of Vitamin D in patients can result in toxicity of Vitamin D. This study was done to estimate the prevalence of vitamin D toxicity in samples submitted for 25OHD analysis to a large volume laboratory.

Material and Methods: An observational study was conducted at the section of Chemical Pathology, Department of Pathology and Microbiology AKUH. Laboratory data analysis of serum 25OHD tests performed from January 2010 to October 2012 was performed. Only initial test results were included in analysis for subjects with repeated testing for 25OHD. The cutoffs used for deficient, insufficient, optimal, hypervitaminosis and toxic levels were, ≤20, 20-30, ≥30, ≥100 and ≥150 ng/ml respectively. Data was analyzed by SPSS version 19.

Results: The increase in 25OHD testing since 2010 to 2012 was 42%. Total 182,526 tests were performed during 36 months period, average age being 35 years. Cumulative prevalence of deficiency, insufficiency, sufficiency, hypervitaminosis and toxicity over three years were 65.1%, 16.5%, 17.8%, 1% and 1.5%. There was a significant increase in samples with hypervitaminosis D & toxicity over the three years from 0.8% (350) to 1.1% (729) & 0.37% (145) to 0.6% (364) respectively. Thirty percent & 42% of the subjects with high hypervitaminosis D & toxicity were of pediatrics age group (age<16yrs). While deficiency was more common in adults with mean age 48.5±10 yrs. While 62% of adult population (>16 - <50yrs) was Vitamin D deficient.

Conclusions: Although prevalence of deficiency, insufficiency and sufficiency remain similar but hypervitaminosis D & toxicity have increased over 3 years. Higher 25OHD levels were more common in pediatric population so we suggest that highly concentrated Vitamin D injections or oral drops should be used with caution