Purpose: Vitamin D deficiency is a common health problem around the world. This study aimed to evaluate the nationwide prevalence of vitamin D status in tertiary care hospitals in Turkey. Methods: Retrospectively, the data of vitamin D levels from 33 tertiary care hospitals’ clinical biochemistry laboratories around Turkey between 2 January 2016 and 31 December 2016 were conducted. Results: In total 706434 serum samples from adult subjects (F/M: 469028/ 237406; 66.4%/ 33.6%) were included. While vitamin D levels were sufficient in 20.3% (n=14222), they were insufficient in 21.9% (n=154360) and deficient in 57.8% (n=408882). Of the deficient group, 25.0% (176608) had levels <10 ng/mL consistent with profound deficiency. We observed the highest rates of deficiency in those aged between 18-29 years 62.9% (n=70235) and lowest rates in 60-69 years (52.3%, n=61121) and in 70-79 years (52.3%, n=32397). Hypervitaminosis D were consisting of 5.5% of adult subjects. highest rates of hypervitaminosis D were observed in over 80 years (6.6%) and 70-79 years (6.5%), and the lowest in 18-29 years (2.8%). Deficiency rates were 55.4% (n=131468) in men and 59.2% (n=277384) in women. Higher deficiency rates were observed in January (67.9%), February (71.6%), and March (66.7%). Conclusion: In this cohort, over half of the subjects admitted to the tertiary care hospitals in Turkey had vitamin D deficiency, required vitamin D supplementation. The elderly population had the lowest prevalence of vitamin D insufficiency and the highest prevalence of hypervitaminosis D. That may indicate overtreatment of vitamin D supplementation in the elderly group.

Purpose: Kidney transplant recipients are prone to metabolic bone diseases and consequent fractures. This study aimed to evaluate the incidence of incipient vertebral fractures, osteopenia, osteoporosis, and the clinical factors associated with incipient vertebral fractures in a group of kidney transplant patients. Methods: Two hundred sixty-four patients (F/M:124/140, 45.3±13 years) who had undergone kidney transplantation between 2008 and 2018 and who were followed up at least one year in third care centers were included in this multicenter retrospective study. Bone mineral densitometry was performed using dual-energy X-ray absorptiometry. Vertebral fractures were assessed semi-quantitatively using conventional thoracolumbar lateral radiography in 202 of the patients. Results: Vertebral fractures were observed in 56.4% (n=114) of the study group. Severe vertebral fractures were observed in 30.7% (n=62) of the patients in vertebral X-ray evaluation. The frequency of osteoporosis was 20.0% (53 of 264 patients), and osteopenia was 35.6% (94 of 264 patients). BMD levels were in the normal range in 40.3% (n=46) of the subjects with vertebral fractures. It was in the osteoporotic range in 20.1% (n=23) and the osteopenic range in 40.3% (n=46). Serum calcium, parathormone vitamin, and creatinine levels were similar between the patients with and without vertebral fractures. Femoral neck BMD was negatively correlated with age (r: −0.21, p<0.001) and positively correlated with body mass index (r:0.29, p<0.001). Vertebral fractures were associated with age, duration of hemodialysis, BMI, femoral neck Z score (R2: 37.8%, p=0.027). Conclusion: BMD was in the normal or osteopenic range in 79.8% in our cohort of renal transplant patients with incipient vertebral fractures. As incipient vertebral fractures can be observed in patients with normal BMD levels in kidney transplant recipients, conventional X-ray screening for vertebral fractures may be beneficial for a proper therapy decision of metabolic bone disease in kidney transplant recipients.