Lower Oxytocin Levels Are Associated with Lower Bone Mineral Density and Less Favorable Hip Geometry in Hypopituitary Men

Abstract

Introduction: Hypopituitary patients are at risk for bone loss. Hypothalamic-posterior pituitary hormones oxytocin and vasopressin are anabolic and catabolic, respectively, to the skeleton. Patients with hypopituitarism may be at risk for oxytocin deficiency. Whether oxytocin and/or vasopressin contribute to impaired bone homeostasis in hypopituitarism is unknown. Objectives: To determine the relationship between plasma oxytocin and vasopressin levels and bone characteristics (bone mineral density [BMD] and hip structural analysis [HSA]) in patients who have anterior pituitary deficiencies only (APD group) or with central diabetes insipidus (CDI group). Methods: This is a cross-sectional study. Subjects included 37 men (17 CDI and 20 APD), aged 20–60 years. Main outcome measures were fasting plasma oxytocin and vasopressin levels, and BMD and HSA using dual X-ray absorptiometry. Results: Mean BMD and HSA variables did not differ between the CDI and APD groups. Mean BMD Z-scores at most sites were lower in those participants who had fasting oxytocin levels below, rather than above, the median. There were positive associations between fasting oxytocin levels and (1) BMD Z-scores at the spine, femoral neck, total hip, and subtotal body and (2) favorable hip geometry and strength variables at the intertrochanteric region in CDI, but not APD, participants. No associations between vasopressin levels and bone variables were observed in the CDI or ADP groups. Conclusions: This study provides evidence for a relationship between oxytocin levels and BMD and estimated hip geometry and strength in hypopituitarism with CDI. Future studies will be important to determine whether oxytocin could be used therapeutically to optimize bone health in patients with hypopituitarism.

Oxytocin and Bone: Review and Perspectives

“…Nevertheless, in the MINOS cohort, there was a weak significant trend for a higher fracture risk in men with a low serum OT level after adjustment for confounders including BMD and serum OT was significantly lower in men with severe osteoporosis compared to men with a normal bone status, suggesting effects of OT on other determinants of fracture risk such as muscle strength [34]. However, in another cross-sectional study including 37 hypopituitary men without any previous history of fracture or any medication for osteoporosis, there was a robust positive association between fasting OT serum levels and BMD (Z-scores at the lumbar spine, femoral neck and total hip) and favorable hip geometry and strength variables at the intertrochanteric region in men with central diabetes insipidus but not in men with anterior pituitary deficiencies [36].…”

New developments and concepts in the diagnosis and management of diabetes insipidus (AVP‐deficiency and resistance)

“…Data regarding oxytocin deficiency in patients with panhypopituitarism or CDI are scarce. Thus, the need for replacement treatment remains mainly theoretical, although a cross‐sectional study demonstrated that low oxytocin levels were associated with lower bone mass density and less favourable hip geometry, 152 as well as with cognitive impairment. Preliminary results provide some evidence of potential benefits of oxytocin therapy with respect to improving these deficits and accompanying metabolic disturbances 153,154 .…”

Dual Oxytocin Receptor-G Protein Signaling in the Autoregulation of Activities of Oxytocin Neurons

“…OT and VP are anabolic and catabolic, respectively, to the skeleton. Patients with high fasting OT levels also have high bone mineral density [153]. In schizophrenic patients, the numerical density of OT degrading enzyme insulin-regulated aminopeptidase-expressing neurons in the PVN and the suprachiasmatic nuclei is significantly reduced, which might be associated with the reduction in neurophysin-containing neurons in these nuclei in schizophrenia [154].…”