Screening for vitamin D deficiency in a tropical area: results of a sun exposure questionnaire

Fernanda Barros Bittar,Charlles H M Castro,Vera Lúcia Szejnfeld

doi:10.1186/s12902-018-0272-0

Fernanda Barros Bittar, Charlles H M Castro + Show 1 more

Open Access

https://doi.org/10.1186/s12902-018-0272-0

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Journal: BMC endocrine disorders	Publication Date: Jul 3, 2018
Citations: 8	License type: open-access

Affiliation: Universidade Federal de São Paulo

Abstract

BackgroundVitamin D deficiency is pandemic while resources available to measure 25-hydroxyvitamin D (25OHD) are limited. The present study aimed to verify whether sun exposure measured by a structured questionnaire could predict serum 25OHD concentrations in healthy Caucasian individuals living in a tropical area.MethodsA cross-sectional study was carried out in subjects living in the greater São Paulo area, Brazil. Two groups of 50 young (20 to 40 years old) and 50 older (60 to 80 years old) subjects (N = 200) answered a structured questionnaire on sun exposure and had blood samples drawn for serum 25OHD concentration measurement during both summer and winter. Anthropometric data were also recorded. Correlation between the questionnaire variables (duration of sun exposure, amount of exposed skin, total sun exposure score - TSES and other data) and serum 25OHD concentration was evaluated.ResultsMean serum 25OHD concentration was 17.60 ± 7.3 ng/mL with no difference between age groups (p = 0.293). TSES weakly correlated with serum 25OHD levels (r = 0.264; p < 0.001). Separate analyzes by age groups demonstrated that TSES correlated significantly with serum 25OHD concentration only in the older subjects during summer (r = 0.322; p = 0.023). Using linear regression analyses, TSES and body mass index (BMI) were significantly associated with serum 25OHD levels. On the other hand, Receiver operating characteristic (ROC) analysis for TSES showed no significance as a screening tool for vitamin D deficiency (p = 0.172).ConclusionSun exposure questionnaire associated with BMI correlates with serum 25OHD concentration with very low accuracy. The use of the questionnaire does not discriminate between vitamin D sufficient and deficient individuals.

Highlights

Vitamin D deficiency is pandemic while resources available to measure 25-hydroxyvitamin D (25OHD) are limited
For this age group mean serum 25OHD concentration was significantly higher in the summer than that measured in the winter (21.58 ± 6.08 ng/mL and 14.95 ± 6.58 ng/mL, respectively, p = 0.003)
Our results demonstrated that the sun exposure questionnaire proposed by Hanwell et al [17] was not able to discriminate vitamin D sufficient from deficient individuals when applied to healthy young and old Caucasian subjects living in a tropical area in Brazil

Summary

Introduction

Vitamin D deficiency is pandemic while resources available to measure 25-hydroxyvitamin D (25OHD) are limited. It has been demonstrated that vitamin D plays an important role in bone development in children, maintenance of bone in adults and prevention of osteoporosis in the elderly [2, 3]. 7-dehydrocholesterol UVB-induced conversion to Vitamin D deficiency is currently one of the most common and neglected medical conditions, affecting a large part of the world population [1, 7]. The increasing concern about the high prevalence of vitamin D deficiency and its skeletal consequences especially among the elderly has led to a large increase in the demand for Bittar et al BMC Endocrine Disorders (2018) 18:44 serum 25OHD measurements, currently the best marker of vitamin D status [8]. The economical impact of such strategies would be rather strong among developing countries with no solid initiatives for public health care [11]

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Conclusion