The High Prevalence of Vitamin D Insufficiency across Australian Populations Is Only Partly Explained by Season and Latitude

Background Inadequate sun exposure and dietary vitamin D intake can result in vitamin D insufficiency. However, limited data are available on actual vitamin D status and predictors in healthy individuals in different regions and by season.Methods We compared vitamin D status [25-hydroxyvitamin D; 25(OH)D] in people &lt; 60 years of age using data from cross-sectional studies of three regions across Australia: southeast Queensland (27&deg;S; 167 females and 211 males), Geelong region (38&deg;S; 561 females), and Tasmania (43&deg;S; 432 females and 298 males).Results The prevalence of vitamin D insufficiency (&le; 50 nmol/L) in women in winter/spring was 40.5% in southeast Queensland, 37.4% in the Geelong region, and 67.3% in Tasmania. Season, simulated maximum daily duration of vitamin D synthesis, and vitamin D effective daily dose each explained around 14% of the variation in 25(OH)D. Although latitude explained only 3.9% of the variation, a decrease in average 25(OH)D of 1.0 (95% confidence interval, 0.7&ndash;1.3) nmol/L for every degree increase in latitude may be clinically relevant. In some months, we found a high insufficiency or even deficiency when sun exposure protection would be recommended on the basis of the simulated ultraviolet index.Conclusion Vitamin D insufficiency is common over a wide latitude range in Australia. Season appears to be more important than latitude, but both accounted for less than one-fifth of the variation in serum 25(OH)D levels, highlighting the importance of behavioral factors. Current sun exposure guidelines do not seem to fully prevent vitamin D insufficiency, and consideration should be given to their modification or to pursuing other means to achieve vitamin D adequacy.<br /

Prospective audit of vitamin D levels of women presenting for their first antenatal visit at a tertiary centre

BackgroundVitamin D deficiency in pregnancy is associated with adverse events such as pre-eclampsia, primary caesarean section and vitamin D deficiency of the newborn. Vitamin D screening in pregnancy is not universal.AimsTo evaluate the vitamin D status of pregnant women at our institution and assess the sensitivity of the current risk-based screening guideline.MethodsA prospective audit of vitamin D levels of all women presenting for their first antenatal booking visit during 3 four-week periods (in 2009-2010) was conducted at the Women's and Children's Hospital, South Australia. The main outcome measure was 25-hydroxyvitamin D3 levels. Information was also collected on body mass index, self-reported ethnicity and whether or not vitamin D testing was indicated based on the hospital guidelines.ResultsFour hundred and seventy-two women consented to inclusion in the audit. 67.4% (318/472) were 'low-risk' according to the hospital guidelines for vitamin D screening. 46.2% of these women and 78.6% of 'high-risk' women were vitamin D deficient (ConclusionsBased on current normal ranges for vitamin D, risk-based screening criteria for vitamin D deficiency in pregnancy fails to detect over half of vitamin D deficient women at our institution. Current South Australian guidelines should be amended in favour of universal screening of vitamin D for all pregnant patients at their booking visit.Kate M. De Laine, Geoff Matthews and Rosalie M. Grivel