A survey of vitamin D status in a northern suburbs practice in Johannesburg, South Africa

Abstract

Background: Hypovitaminosis D is endemic worldwide. With the discovery of extra skeletal receptors for 1,25-dihydroxyvitamin D, the influence of vitamin D (25(OH)D3) deficiency has been investigated in metabolic diseases. In South Africa, little is known about 25(OH)D3 status. Aim: To investigate the 25(OH)D3 status in patients in Johannesburg, and to assess for any correlation between 25(OH)D3 , metabolic diseases and patient demographics and seasonal variation. Methods: A retrospective study of 1000 patients attending a northern suburb practice in Johannesburg was performed. Serum 25(OH)D3 levels, demographics and metabolic data were collected. Results: The mean 25(OH)D3 level was 24.45ng/ml and 74.3% were vitamin D deficient. There was no difference in mean 25(OH)D3 levels between age or gender groups. The lowest mean 25(OH)D3 was in the Indian race (p=0.001), HOMA-IR >2 (p=0.001), fasting glucose >7 (p=0.016) and highest was measured during the summer (p=0.001). There was a significant correlation between 25(OH)D3 level and cholesterol (p=0.001), however no correlation was found with hypertension or diabetes. Conclusion: This study reports a high incidence of hypovitaminosis D especially among Indians. In this study there was no correlation between hypovitaminosis D and metabolic factors except for a negative correlation with the cholesterol level.