Vitamin D and PTH: data from a cross-sectional study in an equatorial population

Abstract

Objective: Investigate the prevalence of vitamin D deficiency in an equato rial population through a large-sample study. Methods: Cross-sectional study with 30,224 healthy individuals from the North Region, in Brazil (Amazônia – state of Pará), who had 25-hydroxy-vitami n D (25(OH)D) and intact parathyroid hormone (PTH) serum levels measured by immunoassay method. Those with history of acute or chronic diseases were excluded. Abnorm al levels of calcium, creatinine, glycemia and albumin were also exclusion criteria. Results: 25(OH)D levels were 29.1 ± 8.2 ng/mL and values <12.7 ng/mL we re equal to < −2 s.d. below average. Hypovitaminosis D was present in 10% of subject s according to the Institute of Medicine (values <20 ng/mL) and in 59%, in con sonance with Endocrine Society (values 20–30 ng/mL as insufficiency and <20 ng/mL as defi ciency) criteria. Individuals were divided according to four age brackets: childr en, adolescents, adults and elderly, and their 25(OH)D levels were: 33 ± 9; 28.5 ± 7.4; 28.3 ± 7.7; 29.3 ± 8.5 ng/mL, respectively. All groups differed in 25(OH)D, except adolescents vs adults. Regression model showed BMI, sex, living zone (urban or rural) and age as independent variables to 25(OH)D levels. Comparing subjects with vitamin D deficiency (<20 ng/mL) to those with vitamin D insufficiency (20–30 ng/mL), a difference between P TH levels in these two groups was observed (95.9 ± 24.7 pg/mL vs 44.2 ± 64.5 pg/mL; P < 0.01). Additionally, the most accurate predictive vitamin D level for subclinical hy perparathyroidism in ROC curve was 26 ng/mL. Conclusion: Our equatorial population showed low prevalence of vitamin D hypovitaminosis ranging with age bracket. The insufficient category by Endocrine Society was corroborated by our PTH data.

Keywords

• epidemiology
• endocrinology
• hypovitaminosis d
• vitamin d