Hypovitaminosis D and secondary hyperparathyroidism in resident physicians of a general hospital in southern Brazil.

OBJECTIVES: To evaluate the prevalence of hypovitaminosis D and secondary hyperparathyroidism in resident physicians of a general hospital in southern Brazil and identify associated factors. DESIGN: Cross-sectional study. POPULATION: Resident physicians of Hospital de Clinicas de Porto Alegre, Porto Alegre, southern Brazil. PARTICIPANTS: Seventythree subjects age 26.4+/-1.9. MEASUREMENTS: Serum PTH, 25- hydroxyvitamin D [25(OH)D], total calcium, phosphorus, magnesium, creatinine, and alkaline phosphatase were measured. In addition calcium, creatinine, and magnesium were measured in urine. Fractional excretion of calcium and magnesium were calculated. Calcium intake was estimated by a food intake questionnaire. RESULTS: Mean serum levels of 25(OH)D were 17.9+/-8.0 ng/ml and 57.4% presented 25(OH)D below 20 ng/ml. Secondary hyperparathyroidism, defined as serum PTH > or =48 pg/ml and normal or low serum calcium, was identified in 39.7% of the individuals. Mean serum levels of magnesium were higher (p=0.02) and the fractional excretion of calcium was lower (p<0.001) in individuals with secondary hyperparathyroidism. Serum PTH levels were positively correlated with body mass index (r=0.33 and p=0.006) and serum magnesium levels (r=0.33 and p=0.02) and negatively correlated with serum 25(OH)D levels (r=-0.33 and p=0.008), estimated calcium intake (r=-0.25 and p=0.04), and fractional excretion of calcium (r=-0.34 and p=0.009). CONCLUSION: Vitamin D deficiency and secondary hyperparathyroidism was very common in resident physicians. Therefore, measures to prevent this situation should be recommended.