Endocrine parameters of cystic fibrosis: back to basics.

Dramatic changes in the life expectancy of cystic fibrosis (CF) patients are occurring, creating a cohort of aging individuals experiencing long-term complications of this chronic disease. The two most common of these complications include CF-related diabetes and CF bone disease. The clinical implications of each have become better understood, as have potential therapies. However, data obtained from the basic science studies of both diseases have not been widely recognized. In this review, we focus on the known and hypothesized pathogenesis of these two disorders. Additionally, the molecular underpinnings of CF will be explained along with the potential interactions with endocrine disease phenotypes.

The effect of energy balance on endocrine function and bone health in youth.

Female athletes are susceptible to both disordered eating and menstrual cycle disturbances (MCDs). Disordered eating in combination with high energy expenditure from exercise can lead to energy deprivation. Current theories suggest that MCDs are caused by energy deprivation rather than by exercise alone. A number of endocrine adaptations occur with energy deprivation and MCDs, which are concomitant with imbalanced bone turnover, reduced bone density and potentially increased fracture risk. This chapter reviews current evidence concerning the disruption of bone metabolism that accompanies disordered eating and MCDs in physically active girls and young women, including high-performance athletes. Initially, an overview of the aetiology of exercise-associated MCDs and their link with disordered eating is provided. Thereafter, studies reporting changes in areal bone mineral density (aBMD) in female athletes with MCDs are considered in conjunction with change in athletes' physical activity, nutritional status and menstrual histories. A comprehensive overview of the disruption of bone metabolism that accompanies nutritionally related MCDs is also provided. Emphasis is placed upon the role of energy deprivation and its endocrine effects, which, when sustained, result in imbalanced bone turnover and low aBMD. Based on current evidence, recommendations are made for the prevention and treatment of disturbed bone metabolism and low BMD in female athletes with MCDs. Finally, consideration is given to the effects of intense training and energy deprivation on endocrine function and skeletal health in men.

Growth hormone in musculoskeletal pain states.

Growth hormone is essential for normal linear growth and the attainment of an adult mature height. It also plays an important role in cartilage growth and the attainment of normal bone mass. There is only one rheumatic disorder, namely acromegaly, in which abnormalities of growth hormone production play a major etiologic role. However, there is increasing appreciation that suboptimal growth hormone secretion, leading to a state of adult growth hormone deficiency, may occur in the setting of chronic inflammatory disease, chronic corticosteroid use, and fibromyalgia. Therefore, the evaluation and effective management of growth hormone oversecretion and undersecretion is relevant to practicing rheumatologists.

[Osteoporosis and metabolic bone diseases; clinical relationship]. / Osteoporose und metabolische Osteopathien: Klinische Relationen.

Metabolic bone diseases with disturbed bone remodeling lead to loss of biomechanical quality and atraumatic fractures. Differential diagnosis, prevention and adequate treatment should already start early in the course of these disorders to prevent fractures. Thus, clinical osteology is more than the simplified connection "low bone mineral density--fractures--osteoporosis". This review summarizes physiological relations between bone tissue and calcium homoeostasis as well as the relation between structure and function. In addition, the main metabolic osteopathies "osteoporosis, primary hyperparathyroidism and osteomalacia" are presented from a clinical point of view. The importance and the diagnostic values of biochemical parameters and of the transiliacal biopsy are discussed. In this respect the quantitative measurement of the mineralization density (bone mineral density distribution = BMDD) seems to be of high value and extends the well established bone histomorphometry. This recently introduced method has the power to distinguish between small differences in the degree of mineralization of the matrix with high precision and reproducibility. The results of quantitative backscattered electron imaging in the scanning electron microscope improve the differential diagnosis of bone diseases with alterations in mineralization density, helps to detect mixed etiology (e.g. osteoporosis plus osteomalacia) and facilitate decision making for treatments. The value of biochemical, radiological, osteodensitometric and histopathological tests for diagnosis and treatment depends on the knowledge of the clinical relations and the complex interactions between calcium-, phosphate- and bone metabolism.

Serum collagen crosslinks as markers of bone turn-over during GH replacement therapy in growth hormone deficient adults.

OBJECTIVES: Bone metabolism is an important target for GH replacement therapy. However, in adults, treatment periods exceeding 12 months are required for a positive effect of GH on bone mineral density. Thus, to detect an early effect of GH on bone, markers of bone turn-over are important. Pyridinoline (PYR) and deoxypyridinoline (DPYR) are well-defined sensitive markers of bone resorption, but to date only urinary assays have been available. We report the use of a novel assay to measure changes in serum PYR and DPYR in GH deficient (GHD) adults during GH replacement therapy. STUDY DESIGN: The study consisted of a 6-month randomized, double-blind, placebo-controlled study of the administration of GH (Genotropin) (0.25 IU/Kg/week (0.125 IU/kg/week for the first four weeks)) followed by a 6-month open phase of GH therapy. PATIENTS: Thirty-five GHD adults (17 women; mean age 39.8 years; range 21.1-59.9) on conventional hormone replacement therapy as required, were studied. MEASUREMENTS: Bone formation was analysed using serum bone alkaline phosphatase (BAP) and serum osteocalcin (OC). Bone resorption was analysed using serum pyridinoline (PYR) and serum deoxypyridinoline (DPYR). Bone mineral density (BMD) was determined by dual energy X-ray absorptiometry (DEXA). RESULTS: After 6 months placebo treatment there were no significant changes in any of the bone markers analysed, nor in BMD. In the active arm of the study there was a significant increase in serum OC, BAP, PYR and DPYR (P = 0.03, P = 0.004, P = 0.003 and P = 0.01, respectively), remaining significantly elevated over their baseline levels for the subsequent 6 months of treatment (P = 0.04, P = 0.009, P = 0.003 and P = 0.04, respectively). No changes were observed in BMD in any of the groups after 6 months GH treatment. In the active arm of the study, after 12 months GH treatment there was a significant increase in BMD at both the lumbar spine and femoral neck (P = 0.01 for both sites). CONCLUSIONS: In summary, the present study confirms that administration of GH treatment to GHD adult patients significantly activates bone remodelling, with the effect of GH both in bone formation and bone resorption markers being maximal after 6 months of treatment. The serum assay for PYR and DPYR has a number of practical and theoretical advantages over the urine assay and gave similar results to those previously reported for the urine assay.

Endocrine aspects of growth deficiency in OI.

Growth deficiency is the most common secondary feature of osteogenesis imperfecta. It is unrelated to fracture history and appears to be due to the growth failure of the defective bony matrix. There are characteristic growth curves for different types of OI. We have been investigating the endocrine features of this disorder, in which the skeletal target tissue synthesizes defective matrix. We review the results of our evaluation of the growth hormone axis in 28 children with short stature and OI and of our pilot study to stimulate OI bone to increased growth rates. Our current focus is on the effect of growth hormone treatment on linear growth, bony mineral and bony matrix in OI.