The role of serum osteoprotegerin and receptor-activator of nuclear factor-κB ligand in metabolic bone disease of women after obesity surgery.

Metabolic bone disease may appear as a complication of obesity surgery. Because an imbalance in the osteoprotegerin and receptor-activator of nuclear factor-κB ligand system may underlie osteoporosis, we aimed to study this system in humans in the metabolic bone disease occurring after obesity surgery. In this study we included sixty women with a mean age of 47 ± 10 years studied 7 ± 2 years after bariatric surgery. The variables studied were bone mineral density, ß-isomer of C-terminal telopeptide of type I collagen cross-links (a bone resorption marker), the bone formation markers osteocalcin and N-terminal propeptide of procollagen 1, serum osteoprotegerin and receptor-activator of nuclear factor-κB ligand. Serum osteoprotegerin inversely correlated with the bone remodeling markers osteocalcin, ß-isomer of C-terminal telopeptide of type I collagen cross-links and N-terminal propeptide of procollagen 1. The osteoprotegerin and receptor-activator of nuclear factor-κB ligand ratio also correlated inversely with serum parathormone and osteocalcin. Bone mineral density at the lumbar spine was associated with age (ß = -0.235, P = 0.046), percentage of weight loss (ß = 0.421, P = 0.001) and osteoprotegerin and receptor-activator of nuclear factor-κB ligand ratio (ß = 0.259, P = 0.029) in stepwise multivariate analysis (R 2 = 0.29, F = 7.49, P < 0.001). Bone mineral density at the hip site was associated only with percentage of weight loss (ß = 0.464, P < 0.001) in stepwise multivariate regression (R 2 = 0.21, F = 15.1, P < 0.001). These data show that the osteoprotegerin and receptor-activator of nuclear factor-κB ligand system is associated with bone markers and bone mineral density at the lumbar spine after obesity surgery.

Serum Bioavailable Vitamin D Concentrations and Bone Mineral Density in Women After Obesity Surgery.

INTRODUCTION: Low bone mass after obesity surgery may arise as a consequence of chronic malabsorption of calcium and vitamin D. However, we have not found any role of serum 25-hydroxyvitamin D or of polymorphisms in the vitamin D receptor gene in previous studies. PURPOSE: To investigate the circulating bioavailable 25-hydroxyvitamin D in women after bariatric procedures and its association with bone mass. PATIENTS AND METHODS: The study consisted of 91 women on follow-up for 7 ± 2 years after bariatric surgery. We measured bone mineral density (BMD), serum parathormone (PTH), 25-hydroxyvitamin D, and vitamin D binding protein (VDBP). All patients were genotyped for two variants in the coding region of VDBP (rs4588 and rs7041). Bioavailable 25-hydroxyvitamin D was calculated in double homozygotes. RESULTS: We found a negative correlation between bioavailable 25-hydroxyvitamin D and PTH (r = -0.373, P = 0.018), but not with BMD at lumbar spine (r = -0.065, P = 0.682) or hip (r = -0.029, P = 0.857). When adjusting by age, similar results were found for PTH (r = -0.441, P = 0.005), BMD at lumbar spine (r = -0.026, P = 0.874) and hip (r = -0.096, P = 0.561). After multivariate linear regression, forcing bioavailable 25-hydroxyvitamin D into the model resulted in a weak significant association with BMD at the lumbar spine (ß = - 0.247, P = 0.025). CONCLUSIONS: Serum bioavailable 25-hydroxyvitamin D concentrations are not associated with bone mass loss after bariatric surgery in women. The negative association with serum PTH levels suggests that vitamin D supplementation partly improves secondary hyperparathyroidism, yet other mechanisms may contribute to low bone mass after bariatric surgery.

Insulinoma: a multicenter, retrospective analysis of three decades of experience (1983-2014).

OBJECTIVE: To analyze the clinical features, diagnostic procedures, treatment, and clinical outcome of insulinomas diagnosed and treated in the period 1983-2014 in four Spanish hospitals. METHODS: All patients with either biochemical and morphological criteria of insulinoma and/or histological demonstration of insulin-secreting tumor were included. RESULTS: Twenty-nine patients [23 women (79.3%); mean age 48.7±17.4 years (range, 16-74)] were recruited. Twenty-six patients (89.7%) had sporadic tumors, and the rest (3 women, 10.3%) developed in the context of multiple endocrine neoplasia type 1. There were 3 (10.3%) multiple insulinomas, one associated with multiple endocrine neoplasia type 1, and two (6.9%) malignant insulinomas, both sporadic. Most patients (n=18, 62.1%) had fasting hypoglycemia, about a third (31%) both postprandial and fasting hypoglycemia, and 6.9% postprandial hypoglycemia only. Time to glucose nadir (37.3±6.5mg/dL) in the fasting test was 9.0±4.4h, with maximal insulin levels of 25.0±20.3µU/mL. Abdominal CT detected insulinoma in 75% of patients. Twenty-seven (93.1%) patients underwent surgery [enucleation, 18 (66.7%) and subtotal pancreatectomy, 9 (33.3%); tumor size, 1,7±0,7cm]. Surgery achieved cure in the majority (n=24, 88.9%) of patients. CONCLUSION: In our setting, insulinoma is usually a benign, small, and solitary tumor, mainly affecting women aged 45-50 years, and usually localized with abdominal CT. The most commonly used surgical technique is enucleation, which achieves a high cure rate.