Fractures in pituitary adenoma patients from the Dutch National Registry of Growth Hormone Treatment in Adults

Cushing's disease and bone

Bone impairment associated with Cushing's disease (CD) is a complex disorder, mainly involving deterioration of bone quality and resulting in an increased fracture rate, often despite normal bone mineral density. Bone complications are common in patients with CD at the time of diagnosis but may persist even after successful treatment. There is currently no agreement on the optimal diagnostic methods, thresholds for anti-osteoporotic therapy and its timing in CD. In this review, we summarize the current data on the pathophysiology, diagnostic approach and management of bone complications in CD.

The influence of growth hormone deficiency on bone health and metabolisms

Growth hormone (GH) is a key peptide hormone in the regulation of bone metabolism, through its systemic and paracrine action mediated directly as well as by insulin-like growth factor-1 (IGF-1). Growth hormone exerts pleiotropic effects leading to an increase in linear bone growth, accumulation of bone mineral content and preservation of peak bone mass. Furthermore, it influences protein, lipid, and carbohydrate metabolism.Growth hormone deficiency (GHD) causes a low bone turnover rate leading to reduced bone mineral density (BMD) and increased bone fragility. The results of GH insufficiency are the most pronounced among children as it negatively affects longitudinal bone growth, causing short stature and in adolescents, in whom it hinders the acquisition of peak bone mass. Most studies show that treatment with recombinant human growth hormone (rhGH) in GHD patients could improve BMD and decrease fracture risk. This review aims to summarize the pathophysiology, clinical picture and management of bone complications observed in GHD.

Skeletal disorders associated with the growth hormone-insulin-like growth factor 1 axis

Growth hormone (GH) and insulin-like growth factor 1 (IGF1) are important regulators of bone remodelling and metabolism and have an essential role in the achievement and maintenance of bone mass throughout life. Evidence from animal models and human diseases shows that both GH deficiency (GHD) and excess are associated with changes in bone remodelling and cause profound alterations in bone microstructure. The consequence is an increased risk of fractures in individuals with GHD or acromegaly, a condition of GH excess. In addition, functional perturbations of the GH-IGF1 axis, encountered in individuals with anorexia nervosa and during ageing, result in skeletal fragility and osteoporosis. The effect of interventions used to treat GHD and acromegaly on the skeleton is variable and dependent on the duration of the disease, the pre-existing skeletal state, coexistent hormone alterations (such as those occurring in hypogonadism) and length of therapy. This variability could also reflect the irreversibility of the skeletal structural defect occurring during alterations of the GH-IGF1 axis. Moreover, the effects of the treatment of GHD and acromegaly on locally produced IGF1 and IGF binding proteins are uncertain and in need of further study. This Review highlights the pathophysiological, clinical and therapeutic aspects of skeletal fragility associated with perturbations in the GH-IGF1 axis.

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

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.

Pituitary Tumors Centers of Excellence

Pituitary tumors are common and require complex and sophisticated procedures for both diagnosis and therapy. To maintain the highest standards of quality, it is proposed to manage patients in pituitary tumors centers of excellence (PTCOEs) with patient-centric organizations, with expert clinical endocrinologists and neurosurgeons forming the core. That core needs to be supported by experts from different disciplines such as neuroradiology, neuropathology, radiation oncology, neuro-ophthalmology, otorhinolaryngology, and trained nursing. To provide high-level medical care to patients with pituitary tumors, PTCOEs further pituitary science through research publication, presentation of results at meetings, and performing clinical trials.

Growth Hormone Effects on Bone Loss-Induced by Mild Traumatic Brain Injury and/or Hind Limb Unloading

Growth hormone (GH) deficiency and loss of physical activity are common features in traumatic brain injury (TBI) patients that may contribute to bone loss. Therefore, we tested the hypothesis that GH treatment will rescue the hind limb unloading (UL)-induced skeletal deficit in TBI mice. Mild TBI was induced once per day for four consecutive days. UL (right hind limb) and treatment (3 mg/day GH or vehicle) began two weeks after the first TBI episode and lasted for four weeks. GH treatment increased femur BMD and lean body mass but decreased the % fat measured by DXA in the Control group. Micro-CT analysis revealed that the TBI, UL and TBI-UL groups showed reduced tibia trabecular (Tb) bone mass by 15%, 70%, and 75%, respectively compared to Control mice and that GH treatment significantly increased Tb. bone mass in all four groups. Vertebra also showed reduced Tb. bone mass in TBI, UL and TBI-UL groups. GH treatment increased vertebral Tb. bone mass in Control and UL groups but not in the TBI or TBI-UL group. GH treatment increased serum IGF-I levels similarly in TBI, UL and TBI-UL groups at day 14, suggesting the GH effect on liver IGF-I production was unaffected by skeletal UL. In contrast, GH effect on expression of ALP, IGFBP5 and axin2 in bone were compromised by UL. In conclusion, skeletal UL caused a greater Tb. bone deficit than mild TBI alone and that GH anabolic effects in the TBI and UL groups vary depending on the skeletal site.

Pituitary Diseases and Bone

Neuroendocrinology of bone is a new area of research based on the evidence that pituitary hormones may directly modulate bone remodeling and metabolism. Skeletal fragility associated with high risk of fractures is a common complication of several pituitary diseases such as hypopituitarism, Cushing disease, acromegaly, and hyperprolactinemia. As in other forms of secondary osteoporosis, pituitary diseases generally affect bone quality more than bone quantity, and fractures may occur even in the presence of normal or low-normal bone mineral density as measured by dual-energy X-ray absorptiometry, making difficult the prediction of fractures in these clinical settings. Treatment of pituitary hormone excess and deficiency generally improves skeletal health, although some patients remain at high risk of fractures, and treatment with bone-active drugs may become mandatory. The aim of this review is to discuss the physiological, pathophysiological, and clinical insights of bone involvement in pituitary diseases.

Experimental repetitive mild traumatic brain injury induces deficits in trabecular bone microarchitecture and strength in mice

To evaluate the long-term consequence of repetitive mild traumatic brain injury (mTBI) on bone, mTBI was induced in 10-week-old female C57BL/6J mice using a weight drop model, once per day for 4 consecutive days at different drop heights (0.5, 1 and 1.5 m) and the skeletal phenotype was evaluated at different time points after the impact. In vivo micro-CT (μ-CT) analysis of the tibial metaphysis at 2, 8 and 12 weeks after the impact revealed a 5%-32% reduction in trabecular bone mass. Histomorphometric analyses showed a reduced bone formation rate in the secondary spongiosa of 1.5 m impacted mice at 12 weeks post impact. Apparent modulus (bone strength), was reduced by 30% (P<0.05) at the proximal tibial metaphysis in the 1.5 m drop height group at 2 and 8 weeks post impact. Ex vivo μ-CT analysis of the fifth lumbar vertebra revealed a significant reduction in trabecular bone mass at 12 weeks of age in all three drop height groups. Serum levels of osteocalcin were decreased by 22%, 15%, and 19% in the 0.5, 1.0 and 1.5 m drop height groups, respectively, at 2 weeks post impact. Serum IGF-I levels were reduced by 18%-32% in mTBI mice compared to contro1 mice at 2 weeks post impact. Serum osteocalcin and IGF-I levels correlated with trabecular BV/TV (r² =0.14 and 0.16, P<0.05). In conclusion, repetitive mTBI exerts significant negative effects on the trabecular bone microarchitecture and bone mechanical properties by influencing osteoblast function via reduced endocrine IGF-I actions.

Endoscopic therapy and curative effect in pituitary adenoma patients complicated by acromegalic cardiomyopathy

The study aimed to retrospectively analyze the clinical characteristics of patients with pituitary adenomas complicated by acromegalic cardiomyopathy and to evaluate the effect of endoscopic surgery. Eighty-six pituitary adenoma patients complicated by acromegalic cardiomyopathy who were treated with endoscopic surgery in the First Affiliated Hospital of Soochow University from January 2010 to December 2016 were enrolled. We noted patient clinical characteristics and explored the relationships with surgical treatment. Before and after surgery, all patients underwent an examination of pituitary endocrinology, brain magnetic resonance (MR), and echocardiography. The serum levels of growth hormone (GH), left ventricular end-diastolic diameter (LVIDd), interventricular septal thickness (IVST), left ventricular posterior wall thickness (LVPWT), left ventricular ejection fraction (EF), and mitral valve (E/A ratio) were examined with non-invasive methods, and the results were compared. Of the 86 patients, there were 23 with microadenomas, 27 with large adenomas, and 36 with giant adenomas. There were 28 patients with invasive adenomas and 58 with non-invasive adenomas. The pre-operative mean GH level was 71.23 ± 3.29 μg/L, which was positively correlated with tumor volume (r = 0.751, P < 0.01). Via trans-sphenoidal endoscopic pituitary adenoma resection, 51 patients underwent total tumor resections, 25 underwent subtotal resections, 8 underwent major part resections, and 2 underwent partial resections. After surgery, the GH mean level was 3.81 ± 1.03 μg/L, which was significantly different (t = 3.72, P < 0.01) from the pre-operative level. Cardiac function indices, including LVIDd, IVST, LVPWT, E/A, and EF, were significantly improved. The long-term curative rate was 39.17% and the remission rate was 77.29%. For pituitary adenoma patients complicated by acromegalic cardiomyopathy, endoscopic surgery resulted in a good curative effect and the growth hormone levels were maintained, which can significantly improve cardiac structure and function.

Ischemic stroke after radiation therapy for pituitary adenomas: a systematic review

Radiation therapy is widely used for the treatment of residual and recurrent pituitary adenomas and proved to effectively control tumor growth. However, it is suggested that this treatment might result in an increased risk of ischemic stroke. This review aims to evaluate the radiotherapy-related risk of stroke in pituitary adenoma patients. PubMed and Embase databases were systematically searched for current literature on ischemic stroke risk after radiotherapy in pituitary adenoma, in accordance with the PRISMA statement. Two authors independently selected eligible studies and extracted data. The New Castle Ottawa-scale was used for quality assessment. Out of 264 publications, 11 studies were selected, including 4394 irradiated patients. Incidence of ischemic stroke ranged from 0 to 11.6% (mean 6.7%). While one large, long term follow-up study showed a threefold increased risk of stroke after radiation therapy, another nationwide study of high quality found no significant difference in stroke risk after irradiation. Four studies, which applied stereotactic radiosurgery (SRS) or Gamma-knife surgery (GKS), found no ischemic strokes. Included studies described different radiation techniques and regimens and different lengths of follow-up. In conclusion, complications of cerebral ischemia after radiotherapy for pituitary adenoma are infrequently reported. Moreover, after correction for several confounders, no significant difference in ischemic stroke rate between irradiated and non-irradiated patients could be identified.