Hyperparathyroidism secondary to hypovitaminosis D in hypoalbuminemic is less intense than in normoalbuminemic patients - A prevalence study in medical inpatients in Southern Brazil

Hypovitaminosis D has been reported in tropical countries, but this hormone has seldom been studied in Brazil. Our purpose was to study the prevalence of hypovitaminosis D in patients hospitalized in internal medicine wards in Southern Brazil. Possible associated factors were studied. We studied 81 adult patients in early spring. Mean serum 25(OH)D was 12 +/- 8.57 ng/mL; hypovitaminosis D was severe (<10 ng/mL) in 27 (33.3%) patients, and moderate (>= 10 ng/mL and <20 ng/mL) in 36 (44.5%) patients. Clinical evaluation did not yield any data associated with hypovitaminosis D. Serum 25(OH)D levels of up to 20 ng/mL were associated with decreased mean serum total calcium (P = 0.001), ionized calcium (p = 0.01), and phosphorus (P = 0.044) levels, and increased mean serum PTH level (P = 0.001). In a multiple regression model, serum PTH level was independently affected by serum total calcium (p = 0.01), phosphorus (p = 0.009), and albumin (p = 0.009) levels. Hypovitaminosis D patients had lower mean serum albumin levels (p = 0.004), and serum 25(OH)D levels were directly correlated to serum albumin levels (p < 0.0001). Albumin influenced independently PTH response to hypovitaminosis D; normoalbuminemic hypovitaminosis D patients had higher mean serum PTH than hypoalbuminemic patients. Conclusion: Hypovitaminosis D prevalence was very high in medical inpatients in Southern Brazil, in early spring. Nevertheless, secondary hyperparathyroidism was less intense in hypoalbuminemic hypovitaminosis D patients suggesting that in these patients free serum 25(OH)D was closer to normal.