Vitamin D deficiency is a problem for adult out-patients? A university hospital sample in Istanbul, Turkey.

Objective: To investigate the frequency of vitamin D deficiency in relation to demographics, clinical diagnosis, season of measurement and laboratory parameters in adult out-patients. Design: Descriptive, retrospective study concerning evaluation of the initial 25-hydroxyvitamin D (25(OH)D) levels determined at admission in relation to demographics, clinical diagnosis, season of measurement and laboratory parameters. 25(OH)D levels ,20ng/ml were classified as deficiency, 20‐30ng/ml as insufficiency and .30ng/ml as sufficiency. Setting: Out-patient clinics at a tertiary care centre. Subjects: A total of 2488 adult patients (mean age: 53? 3( SD 15?2) years; 85?2% were females) admitted to out-patient clinics at Baskent University Istanbul Hospital were included. Results: Mean level of 25(OH)D in the overall population was 17? 4( SD 11?5)ng/ml while insufficiency and deficiency were evident in 24% and 66% of patients, respectively. Mean 25(OH)D levels in males .45 years old were higher than in their female counterparts (19? 4( SD 11?3)ng/ml v .1 7? 8( SD 12?2)ng/ml; P ,0?05). Mean 25(OH)D levels obtained in summer (18? 6( SD 11?1)ng/ml) and autumn (23? 3( SD 13?6)ng/ml) were significantly higher than levels in spring (16?1 (SD 10?3)ng/ml) and winter (14? 6( SD 10?2)ng/ml; P ,0?01). Mean 25(OH)D levels were determined to be significantly lower in obese patients compared with non-obese patients (15? 6( SD 10?4)ng/ml v .1 7? 6( SD 11?6)ng/ml; P ,0?05). Levels of 25(OH)D were significantly negatively correlated with serum parathyroid hormone levels (r 52 0?194; P ,0?001) while significantly positively correlated with phosphorus (r 50?059; P ,0?01) and HDL cholesterol (r 50?070; P ,0?01) levels. Conclusions: Our findings indicate that vitamin D deficiency is very common among out-patients in Turkey, regardless of gender and age, especially among obese people and during winter and spring.