Osteometabolic and osteogenetic pattern of Turkish immigrants in Germany.

INTRODUCTION: The etiology of osteoporosis comprises environmental and genetic factors. This study investigated vitamin D deficiency and specific genetic alterations of bone metabolism in a group of 183 Turkish immigrants in Germany in comparison with 46 age and sex matched healthy German controls (females in both groups were pre-menopausal). METHODS: Bone mineral density (BMD) was measured by dual-energy X-ray absorptiometry. Serum levels of osteologic parameters were determined after overnight fasting. Polymorphisms of the vitamin D receptor (VDR) and lactase genes were genotyped using genomic DNA from peripheral leukocytes. Statistical analysis comprised student's t-test, Mann-Whitney rank sum test, Chi-square analysis and Fisher's exact test. RESULTS: Severe 25-OH D3 hypovitaminosis (83.1%) and elevated parathyroid hormone (82%) were common among immigrants. Osteoporosis but not osteopenia was more prevalent in immigrants. Among immigrants with osteoporosis, TRAP5b was elevated in 26.7%, and ß-crosslaps in 13.3%. Only the FokI FF VDR-gene-polymorphism was significantly more prevalent among immigrants. In contrast, Ff-genotyped Turkish women exhibited significantly decreased BMD. Lactase polymorphisms were significantly more common among immigrants (84.2% vs. 30.4%) and the CC genotype was commonly associated with reduced BMD (41.6%) but rarely osteoporosis (8.4%). CONCLUSIONS: Vitamin D deficiency, secondary hyperparathyroidism and osteoporosis are common among Turkish immigrants in Germany. Thus, in this population osteologic parameters and BMD should be analyzed and deficiencies be treated. Specifically, the VDR gene polymorphism FokI Ff is of clinical value in identifying females at risk of osteoporosis. In contrast, LCT polymorphisms, though common, do not appear to be a risk factor.

High prevalence of vitamin D deficiency, secondary hyperparathyroidism and generalized bone pain in Turkish immigrants in Germany: identification of risk factors.

INTRODUCTION: The aim of the study was to determine the prevalence of vitamin D deficiency, secondary hyperparathyroidism (sHPT), generalized bone pain and predictors of vitamin D deficiency in a cohort of 994 healthy adult urban residents (589 males, 405 females; age range: 16-69 years) consisting of 101 Germans, 327 Turkish residents of Turkey and 566 Turkish immigrants living in Germany. METHODS: The mean (+/- standard deviation) for 25-hydroxyvitamin D [25(OH)D] and biointact parathyroid hormone (BioPTH) for the German men and women was 68.4 nmol/l and 26.7 pg/ml, respectively. Turkish residents of Turkey had a mean 25(OH)D and BioPTH of 40.6 nmol/l and 27.5 pg/ml, respectively, whereas Turkish residents of Germany had a 25(OH)D of 38.1 nmol/l and a BioPTH of 35.6 pg/ml. RESULTS: Vitamin D insufficiency was common among Turkish nationals independent of whether they lived in Turkey or Germany; 75% had 25(OH)D levels of <50 nmol/l. Turkish females had a higher prevalence of 25(OH)D deficiency (<25 nmol/l) than Turkish males: 30 and 19% of Turkish females living in Germany and Turkey were severely vitamin D deficient compared to 8% and 6% of Turkish males living in Germany and Turkey, respectively. With respect to BioPTH levels, 31% of Turkish females and 21% of Turkish males had elevated BioPTH levels in contrast to only 15% of females and 4% of males living in Turkey. Unconditional logistic regression analysis identified the most important predictors for low 25(OH)D levels as sex, body mass index, lack of sun exposure and living at a higher latitude. Additionally, wearing a scarf and number of children were found to be an independent risk factor for vitamin D deficiency in Turkish women living in Turkey and Germany. A strong correlation between low 25(OH)D levels and higher rates and longer duration of generalized bone and/or muscle aches and pains (often diagnosed as fibromyalgia) was observed. CONCLUSION: Secondary hyperparathyroidism and vitamin D deficiency was found to be common among Turkish immigrants living in Germany, especially in veiled women. Therefore, the monitoring of vitamin D status--i.e. 25(OH)D and PTH--in Turkish immigrants is warranted and once a deficiency is identified, it should be appropriately treated.