Idiopathic juvenile osteoporosis--an analysis of the muscle-bone relationship.

INTRODUCTION: Idiopathic Juvenile Osteoporosis (IJO), a disease of unknown etiology, manifests typically by pain, bone deformities and fractures. Due to limits in BMD data interpretation, evaluation of the muscle-bone functional unit has recently been proposed as a means to assess the general competence of the skeleton. The aim of this study was to evaluate skeletal status during the acute phase of IJO and during recovery from the disease in relation to muscles. MATERIALS AND METHODS: The study population comprised 61 IJO children, including 34 girls (mean age: 13.6+/-3.1 years; range: 7-18) and 27 boys (14.3+/-3.3; 5-18 years). DXA total body (TB) and lumbar spine (S) bone mineral content (BMC) and density (BMD) were measured. Lean body mass (LBM) was employed to calculate SBMC/LBM, TBBMC/LBM, body height (BH)/LBM and LBM/body weight (BW) ratios. Previously established references for healthy controls were utilized for the calculation of Z-score values in IJO cases in respect to phase of the disease. RESULTS: IJO patients had significantly decreased Z-score values for TBBMD, SBMD, SBMC/LBM and TBBMC/LBM ratios but not for the LBM and BH/LBM or LBM/BW ratios. During the acute phase IJO girls had mean Z-scores for TBBMD and SBMD of -2.49+/-0.61 and -3.27+/-1.03, respectively, which were significantly lower than Z-scores during the recovery phase: -0.90+/-0.66, -1.38+/-0.95 (p<0.0001). IJO boys during the acute phase had Z-scores of -2.08+/-0.65 and -2.75+/-1.19 for TBBMD and SBMD, respectively, which were significantly lower than those during the recovery phase (-0.51+/-1.04 and -1.39+/-1.49; p<0.0001). Further, during the acute phase, TBBMC/LBM Z-scores of -2.95+/-1.15 and -2.56+/-1.49 were noted in girls and boys, respectively; the corresponding SBMC/LBM Z-scores were -2.66+/-1.07 and -2.22+/-1.62. During the recovery from IJO, TBBMC/LBM and SBMC/LBM Z-scores of -1.07+/-0.99 and -0.91+/-1.16 and of -1.15+/-1.40 and -0.68+/-1.45 were noted in girls and boys, respectively, and all were significantly higher than those during the acute phase (p<0.0001). CONCLUSIONS: The results of this study indicate that IJO is a bone disorder characterized by an imbalanced muscle-bone relationship and fractures at onset and during the acute phase and by at least a partial recovery without bone pain and new fractures. Implementation of the BH/LBM, TBBMC/LBM and SBMC/LBM ratios to the armamentarium of pediatricians diagnosing bone disorders will provide mechanically meaningful data for diagnostic purposes and, hopefully, for proper therapeutic decisions.

Beneficial effect of liver transplantation on bone mineral density in small infants with cholestasis.

Reports of bone mineral density in children after liver transplantation are few. Eleven cholestatic children were analyzed before and 6 months after liver transplantation. No changes in serum levels of calcium, alkaline phosphates, or 25OHD were observed before versus after LTx. The serum levels of phosphorus and 1-25(OH)2D3 as well as total bone mass density and Cole index were significantly increased after liver transplantation.

Bone turnover rate in postmenopausal women: bimodal distribution?

There is considerable evidence that elevated bone turnover is an independent form of low bone mineral density (BMD) risk factor of osteoporotic fractures. The aim of our study was to test whether a group of postmenopausal women could be divided into subgroups of high and low bone turnover rate using different pairs of bone turnover markers (one resorption, one formation). Cluster analysis was used to obtain high and low bone turnover subgroups within the study group. A magnitude of difference in lumbar spine BMD (expressed as Z-score) between high- and low-turnover groups was used as a criterion of division success. According to this criterion, the division obtained with a urinary type I collagen crosslinked N-telopeptide/bone alkaline phosphatase pair of markers appeared to be the most significant. This method of separation of two subgroups was highly concordant with the division based on the upper thresholds of the normal values for those markers found for the premenopausal women. It seems that the observed existence of high-and low-turnover subject clusters is not an incidental phenomenon, because the effects obtained for the whole study group were further confirmed by the consistent results of cluster analysis, performed separately for two randomly selected subgroups (A and B) from the study group. The results obtained appear to support the view that bone turnover rate in postmenopausal women is distributed in the bimodal fashion. This finding seems to justify further investigations of more elaborated models, enabling clinicians to individually classify their patients as low- or high-turnover cases with higher efficiency, as in the case of cutoff values for single markers.

Potential of densitometric measurement in selected pediatric subject.

On the aim to recognize bone mineral measurements as somatic development parameter as well as its clinical usefulness in pediatric clinic, the investigations with of DPX-L were performed. Material consisted of 302 healthy scholars both sex and 85 patients aged 6.0-18.9 yrs children diagnosed as idiopathic juvenile osteoporosis (IJO) and osteogenesis imperfecta (OI). Total body mineral density (TBBMD) was evaluated as developmental parameter in normal children population and utilized in differential diagnosis and monitoring of bone pathology in children with IJO and OI.

[Evaluation of bone mass in children in a national sample of the population]. / Ocena masy kostnej u dzieci w krajowej próbie populacyjnej.

Dual energy X-ray absorptiometry (DEXA) was used to measure a mean bone mineral density (BMD) and bone mineral content (BMC) in total body and lumbar spine (L2-L4--BMD; L2-L4--BMC) in a group of 306 healthy children of both sexes, aged between 6 and 18 years. Step-wise increase in BMD in peripubertal age was noted. A degree of an increase in BMD at the age of 10 and 16 years was higher in boys than in girls. Bone mineral density of the spine was lower in the Polish population than that in USA. A high degree correlation between densitometric measurements and calendar age, and body height and weight was noted.

[Dynamics of the course of idiopathic juvenile osteoporosis]. / Dynamika przebiegu idiopatycznego osteoporozy mlodzienczej.

Clinical course of the idiopathic juvenile osteoporosis (IJO) was monitored in the group of 45 patients of both sexes with diagnosed disease, verified during follow-up period. The aim of the study was to evaluate the relationship between clinical symptoms and the results of biochemical, anthropometric, and densitometric measurements. An analysis of the obtained data enabled to distinguish the acute and chronic IJO phases. Evolution of the acute phase into chronic one was manifested by the cessation of pain and pathological gait stereotype, normalization of muscular strength, anthropometric parameters and urinary Pyr and DPyr excretion, as well as improvement in bone density. Hypercalciuria and increased urinary excretion of Pyr and DPyr, observed in the acute phase of IJO, may indicate that bone resorption exceeded bone formation. Tendency to maintain of alkaline phosphatase activity within lower limits of the normal values with slight increase during an improvement of densitometric parameters suggested transient osteoblast dysfunction.

[Pyridinoline and deoxypyridinoline excretion in urine of healthy children--dependence on age]. / Wydalanie pirydynoliny i dezoksypirydynoliny w moczu dzieci zdrowych--zaleznosc od wieku.

Pyridinoline (Pyr) and deoxypyridinoline (DPyr) are crosslinking compounds of bone collagen. Their urinary excretion is considered to be the first sensitive and specific marker of bone resorption in a number of metabolic bone diseases in adults. Application of crosslinks measurements to evaluate bone turnover rate in pediatric patients is so far limited because of lack of reference values. Therefore, the aim of our study was to determine urinary excretion of Pyr and DPyr in healthy children aged 3-18 yrs, and to evaluate the possible relationship between the levels of both compounds and body height, weight, BMC, and BMD. Pyr and DPyr levels were determined in first void urine samples obtained from 249 children (124 boys, 125 girls). Urine aliquots were hydrolysed, Pyr and DPyr extracted on CF1 cellulose, and analysed by HPLC with fluorimetric detection. Bone mineral content (BMC) and density (BMD) were measured with Lunar DPX-L apparatus in 205 children (104 boys, 101 girls) from the same population, aged over 5.5 yrs. In prepubertal children, a tendency towards lowering of urinary Pyr and DPyr levels with advancing age was shown. At puberty, urinary excretion of both crosslinks markedly decreased. This phenomenon was observed at various calendar age in girls as compared to boys, reflecting sex-dependent differences. Significant negative correlation (p < 0.0001) between urinary Pyr and DPyr levels and calendar age, body height and weight, BMC and BMD, were also found. The obtained results suggest that references values for Pyr and DPyr excretion in growing children should be related to calendar age, sex, and--in case of adolescents--phase of puberty.