[Secondary osteoporosis or secondary contributors to bone loss in fracture. Endocrinological aspects of bone metabolism].

Bone works to play essential roles in mineral metabolism and hematopoiesis as well as to support our body and protect internal organs as a hard tissue. In order to accomplish these multiple functions, bone needs to communicate with other organs. Endocrine system functions as one of the communication pathways between bone and other organs. It has been known that bone is a target organ of many hormones. In addition, it has been established that bone itself produces hormones and works as an endocrine organ.

Stem cells in skeletal physiology and endocrine diseases of bone.

Self-renewing, multipotent progenitors of skeletal tissues are found within skeletal segments (skeletal stem cells) and coincide with adventitial reticular cells of bone marrow vessels in situ and with explanted clonogenic stromal cells ex vivo. These cells, which can be identified and prospectively isolated based on a minimal surface phenotype noted for expression of CD146, CD105 and alkaline phosphatase, are established during bone development through interactions with developing sinusoids. They represent a crucial crossroad of skeletal and hematopoietic physiology, as well as of endocrine regulation of bone growth and remodeling. In addition, they are central to major endocrine functions of bone itself, such as regulation of renal phosphate handling. Skeletal stem cells represent a central model system for investigating skeletal diseases, as tools for in vitro and in vivo models, for cell therapy-based strategies, or as targets for drugs.

Ratio of cyclase activating and cyclase inactive parathormone (CAP/CIP) in dialysis patients: correlations with other markers of bone disease.

PURPOSE: We checked correlation of CAP/CIP with osteoprotegrin (OPG), its soluble ligand (OPGL) and routinely measured parameters of bone turnover in patients treated with peritoneal dialysis (PD) and hemodialysis (HD). MATERIAL & METHODS: In 30 patients (22 HD, 8 PD) we determined serum concentrations of intact parathormone (iPTH), CAP, OPG, OPGL, total Ca, inorganic phosphates (Pi), creatinine, urea, total alkaline phosphatase (AP) and blood pH. CIP was calculated by subtraction of CAP from iPTH. Controls (Cs) included 9 healthy persons in whom iPTH, CAP, OPG and OPGL were measured as well as CIP, CAP/CIP and OPGL/OPG were calculated. RESULTS: Differences between HD and PD patients included dialysis duration, OPGL, OPGL/OPG, AP, Pi, Ca and pH. After adjustment to dialysis duration differences in OPGL/OPG, Pi, Ca and pH remained significant. HD patients differed from Cs in terms of iPTH, CAP, CIP, OPGL, OPG and OPGL/OPG. In whole group of patients iPTH, CAP, CIP but not CAP/CIP correlated negatively with OPGL and OPGL/OPG as well as positively with dialysis duration, OPG and AP. CONCLUSIONS: Despite more advanced uremic bone disease in longer dialyzed HD patients than in shorter dialyzed PD ones, CAP/CIP is not different neither between these groups nor Cs persons. CAP/CIP does not seem to be more powerful tool in noninvasive diagnosis of bone disease than iPTH or CAP and CIP alone.

Endocrine changes after burns: the bone involvement.

Any major burn is followed by a pronounced endocrine and metabolic response, by an acute phase response. In 30 burn subjects whose bone status was studied after burn trauma with the densitometer HOLOGIC 2000, bone involvement was found 6 and 12 months postburn: the Bone Mineral Density (BMD) of their lumbar vertebrae L1-4 and of their left hip dropped significantly in most of them. Elevated levels of cortisol both in blood and in urine (free cortisol) were found, accompanied by very low testosterone, dihydrotestosterone (DHT) and free testosterone levels in blood of the burned males, but not of the females. Elevated 17beta-estradiol levels were found in many burned males; they were generally not low in the burned females. DHEA-S levels were generally low. Very low levels of the triiodothyronine (T3) and of the free thyroxine (FT4) were found. Increased, even very high, PTH values were occasionally present. hGH and IGF-1 were generally normal, with a few exceptions (low or increased levels). Total and ionized calcium levels were low after burn, 250H vitamin D (calcidiol) was usually low or low normal too. Prolonged and very high levels of CTX and of NTX (both are indicators of bone resorpcion, of collagen catabolism) were found, as well as of the ACP (acid phosphatases), but the latter were less manifest, if compared with the CTX and NTX. ALP (alkaline phosphatases) were elevated too, but their elevated levels were much less pronounced than the levels of CTX and NTX. Osteocalcin levels were initially low to low normal, to increase later to the normal levels. As for the cytokines that had been investigated, mostly the elevated levels of TNFalpha were found, as well as those of IL-2, IL-6 and IL-8. Finally, a few suggestions have been given regarding the additional possibilities how to treat the burned patients: the use of anabolics, of vitamin D, of calcium, eventually of calcitonin.