Appendicular Muscle Mass Index as the Most Important Determinant of Bone Mineral Content and Density in Small for Gestational Age Children.

Preterm small for gestational age (SGA) children are at increased risk for low bone mineral content later in life; however, data on SGA children born at term are scarce. We included 44 SGA and 57 adequate for gestational age (AGA) children aged 6 to 11 years to compare bone mineral density (BMD) and bone mineral content (BMC) and to identify which anthropometric and biochemical values influence bone mineralization in these children. Fat mass, appendicular skeletal muscle mass index (ASMMI), BMC, and BMD were significantly lower in SGA children than in AGA (P ≤ .005). Appendicular muscle mass index correlated with BMC(TBLH,FN,L1-L4) and BMD(TBLH,FN,L1-L4) in both groups (r2 = 0.7, P < .05). In multivariate analysis, ASMMI was strongly associated with BMC and BMD in both groups. There were no differences in clinical biomarkers, calcium intake, and physical activity between the groups. Achieving adequate muscle mass contributes to adequate bone mineralization and a lower risk for low BMC and BMD in SGA children.

Low prolactin levels are associated with visceral adipocyte hypertrophy and insulin resistance in humans.

PURPOSE: Low prolactin (PRL) serum levels are associated with glucose intolerance and type 2 diabetes in adults, and with metabolic syndrome and obesity in children. In obese rodents, PRL treatment promotes insulin sensitivity by maintaining adipose tissue fitness, and lack of PRL signaling exacerbates obesity-derived metabolic alterations. Since adipose tissue dysfunction is a key factor triggering metabolic alterations, we evaluated whether PRL serum levels are associated with adipocyte hypertrophy (a marker of adipose tissue dysfunction), insulin resistance, and metabolic syndrome in lean, overweight, and obese adult men and women. METHODS: Samples of serum and adipose tissue from 40 subjects were obtained to evaluate insulin resistance index (homeostasis model assessment of insulin resistance (HOMA-IR)), signs of metabolic syndrome (glucose levels, high-density lipoproteins, triglycerides, blood pressure, and waist circumference), as well as adipocyte size and gene expression in fat. RESULTS: Lower PRL serum levels are associated with adipocyte hypertrophy, in visceral but not in subcutaneous fat, and with a higher HOMA-IR. Furthermore, low systemic PRL levels together with high waist circumference predict an elevated HOMA-IR whereas low serum PRL values in combination with high blood glucose predicts visceral adipocyte hypertrophy. In agreement, visceral fat from insulin resistant subjects shows reduced expression of prolactin receptor. However, there is no association between PRL levels and obesity or signs of metabolic syndrome. CONCLUSIONS: Our results support that low levels of PRL are markers of visceral fat dysfunction and insulin resistance, and suggest the potential therapeutic value of medications elevating PRL levels to help maintain metabolic homeostasis.