Paricalcitol downregulates myocardial renin-angiotensin and fibroblast growth factor expression and attenuates cardiac hypertrophy in uremic rats.

BACKGROUND: Vitamin D attenuates uremic cardiac hypertrophy, possibly by suppressing the myocardial renin-angiotensin system (RAS) and fibroblast growth factors (FGFs). We compared the suppression of cardiac hypertrophy and myocardial expression of RAS and FGF receptor genes offered by the vitamin D analog paricalcitol (Pc) or the angiotensin-converting enzyme inhibitor enalapril (E) in experimental uremia. METHODS: Rats with 5/6 nephrectomy received Pc or E for 8 weeks. Renal function, systolic blood pressure, and cardiac hypertrophy were evaluated. Myocardial expression of RAS genes, brain natriuretic peptide (BNP), and FGF receptor-1 (FGFR-1) were determined using quantitative reverse-transcription (pRT)-PCR. RESULTS: Blood pressure, proteinuria, and serum creatinine were significantly higher in untreated uremic animals. Hypertension was significantly reduced by E but only modestly by Pc; however, cardiac hypertrophy in the untreated group was similarly attenuated by Pc or E. Upregulation of myocardial expressions of renin, angiotensinogen, FGFR-1, and BNP in untreated uremic animals was reduced similarly by Pc and E, while the angiotensin II type 1 receptor was downregulated only by E. CONCLUSIONS: Uremic cardiac hypertrophy is associated with activation of the myocardial RAS and the FGFR-1. Downregulation of these genes induced by Pc and E results in similar amelioration of left ventricular hypertrophy despite the different antihypertensive effects of these drugs.

Clinical practice guidelines for the prevention, diagnosis, evaluation and treatment of mineral and bone disorders in chronic kidney disease (CKD-MBD) in adults.

The clinical practice guidelines for the prevention, diagnosis, evaluation and treatment of chronic kidney disease mineral and bone disorders (CKD-BMD) in adults, of the Latin American Society of Nephrology and Hypertension (SLANH) comprise a set of recommendations developed to support the doctor in the management of these abnormalities in adult patients with stages 3-5 kidney disease. This excludes changes associated with renal transplantation. The topics covered in the guidelines are divided into four chapters: 1) Evaluation of biochemical changes, 2) Evaluation of bone changes, 3) Evaluation of vascular calcifications, and 4) Treatment of CKD-MBD. The guidelines are based on the recommendations proposed and published by the Kidney Disease: Improving Global Outcomes (KDIGO) for the prevention, diagnosis, evaluation and treatment of CKD-MBD (KDIGO Clinical practice guidelines for the diagnosis, evaluation, prevention and treatment of Chronic Kidney Disease Mineral and Bone Disorder [CKD-MBD]), adapted to the conditions of patients, institutions and resources available in Latin America, with the support of KDIGO. In some cases, the guidelines correspond to management recommendations directly defined by the working group for their implementation in our region, based on the evidence available in the literature. Each chapter contains guidelines and their rationale, supported by numerous updated references. Unfortunately, there are few controlled studies with statistically sufficient weight in Latin America to support specific recommendations for the region, and as such, most of the references used correspond to studies carried out in other regions. This highlights the need to plan research studies designed to establish the current status of mineral and bone metabolism disorders in Latin America as well as defining the best treatment options for our population.

Suppression of renin-angiotensin gene expression in the kidney by paricalcitol.

The renal renin-angiotensin system plays a major role in determining the rate of chronic renal disease progression. Treatment with activators of the vitamin D receptor retards the progression of experimental chronic renal disease, and vitamin D is known to suppress the renin-angiotensin system in other organs. Here we determined if the beneficial effects of paricalcitol (19-nor 1,25-dihydroxyvitamin D(2)) were associated with suppression of renin-angiotensin gene expression in the kidney. Rats with the remnant kidney model of chronic renal failure (5/6 nephrectomy) were given two different doses of paricalcitol thrice weekly for 8 weeks. Paricalcitol was found to decrease angiotensinogen, renin, renin receptor, and vascular endothelial growth factor mRNA levels in the remnant kidney by 30-50 percent compared to untreated animals. Similarly, the protein expression of renin, renin receptor, the angiotensin type 1 receptor, and vascular endothelial growth factor were all significantly decreased. Glomerular and tubulointerstitial damage, hypertension, proteinuria, and the deterioration of renal function resulting from renal ablation were all similarly and significantly improved with both treatment doses. These studies suggest that the beneficial effects of vitamin D receptor activators in experimental chronic renal failure are due, at least in part, to down-regulation of the renal renin-angiotensin system.

Apoptotic stress pathway activation mediated by iron on endothelial cells in vitro.

BACKGROUND: Iron sucrose (Fe-S) and low-molecular-weight iron dextran (Fe-D) have been used successfully in the treatment of anaemia in chronic kidney disease patients. However, some side effects, such as endothelial cell dysfunction have been reported. Mechanisms by which iron can induce endothelial cell damage have not been completely understood. This study was designed to examine the effect of Fe-S and Fe-D on bovine aortic endothelial cells in vitro. METHODS: Cell proliferation was determined by [3H] thymidine incorporation, cytotoxicity by lactate dehydrogenase, pro-Caspase-3 by immunoblotting; and Caspase-3 activity using a colorimetric assay. Expression of the apoptosis stress pathway proteins Bcl-2 and Bax and cycle arrest proteins p53 and p21WAF/CIP1 were examined by immunoblot. Cell apoptosis was tested by terminal deoxynucleotidyltransferase-mediated nick-end labelling (TUNEL) and DNA fragmentation. RESULTS: Both iron preparations inhibited cell proliferation. This effect was more important and occurred at lower concentrations in Fe-S than Fe-D cultured cells. Expression of p53 and p21WAF/CIP1 increased in cells incubated with Fe-S, but not with Fe-D. Bcl-2 expression was significantly down-regulated in cells incubated with Fe-S in comparison with Fe-D, while Bax expression was not modified by the iron compounds. Pro-Caspase-3 expression and Caspase-3 activity increased only in cells treated with Fe-S. Apoptosis was present in cells treated with Fe-S. CONCLUSIONS: Our results demonstrate that Fe-S exerts a greater inhibitory effect on endothelial cell proliferation than Fe-D. The mechanisms involved in this process may be related, at least in part, to over expression of proteins related to the cell cycle arrest and apoptosis stress pathway.

Bone disease in idiopathic hypercalciuria.

PURPOSE OF REVIEW: Decreased bone mineral density and increased prevalence of bone fractures have been found in patients with idiopathic hypercalciuria. The purpose of this review is to summarize the recent published evidence that supports a potential role of the bone, and its link to the kidney and intestine, in the pathogenesis of idiopathic hypercalciuria. The effects of hypercalciuria on bone and the implications for treatment are also reviewed. RECENT FINDINGS: Evidence suggests that the incidence of a first fracture in kidney stone patients is fourfold higher than the control population. Support for the role of bone in the pathophysiology of hypercalciuria has been corroborated. New studies have detailed the effects of several cytokines - increased number and sensitivity of vitamin D receptors, and increased acid production - upon the bone acting cells. Similarly, recent clinical and experimental studies have suggested that genetic factors confer a predisposition to the formation of renal calcium stones and bone demineralization. SUMMARY: Whether hypercalciuria is the result of a primary bone disorder, a consequence of a persisting negative calcium balance or a combination of both still remains to be determined. Nevertheless, bone status must be evaluated and followed up in patients with idiopathic hypercalciuria.

Bone disease after renal transplantation.

It has been well established that a rapid decrease in bone mineral density (BMD) occurs in the first 6 to 12 mo after a successful renal transplantation and persists, albeit at a lower rate, for many years. This rapid BMD loss significantly increases the fracture risk of these patients to levels that are even higher than those of patients who have chronic kidney disease stage 5 and are on dialysis. The presence of low BMD in renal transplant patients as a predictor of risk fracture is controversial. Indeed, as has been suggested also for patients with postmenopausal osteoporosis, there is not a compelling correlation between the decline in BMD and skeletal fractures. However, bone disease after renal transplantation probably represents a unique bone disorder that must encompass underlying renal osteodystrophy. In fact, this syndrome results from multiple factors that include pretransplantation bone status, use of glucocorticoids and other immunosuppressive drugs, hypophosphatemia, and alterations of the calcium-vitamin D axis. Recent studies have demonstrated decreased osteoblast number, reduced bone formation rate, delayed mineralization, and increased osteoblast and osteocyte apoptosis. Bisphosphonates and vitamin D metabolites may be valuable in preventing or diminishing early bone loss. However, clinicians should be careful with the use of bisphosphonates and oversuppression of bone, especially in patients with low bone turnover. New prospective, controlled trials are required to confirm the real efficacy of these drugs, particularly in long-term renal transplant patients.

Increased osteoblastic activity and expression of receptor activator of NF-kappaB ligand in nonuremic nephrotic syndrome.

Patients with nephrotic syndrome (NS), even with normal GFR, often display altered mineral homeostasis and abnormal bone histology. However, the latter, mostly osteomalacia and increased bone resorption, cannot be readily explained by the prevalent concentrations of parathyroid hormone and vitamin D metabolites. The transmembrane receptor activator of NF-kappaB ligand (RANKL) of osteoblasts is essential for osteoclast formation and differentiation. Osteoblasts activity and the expression of RANKL were tested in cultures of normal human osteoblasts with sera obtained from patients with NS and normal GFR (129 +/- 26 ml/min per 1.73 m2) during relapse and remission of their NS. Osteoblasts that were cultured in vitro with sera during relapse displayed elevated concentrations of alkaline phosphatase (AP) and increased expression of RANKL. By contrast, during remission, AP concentrations were significantly lower (P < 0.05) and RANKL expression notably attenuated or absent. AP correlated with the proteinuria (r = 0.5, P < 0.05) and was not significantly affected by the therapeutic administration of corticosteroids. Whereas parathyroid hormone levels were normal (35 +/- 21 pg/ml), the serum markers of bone formation (osteocalcin and bone-specific alkaline phosphatase) were lower during relapse compared with remission. Thus, sera from patients with NS and normal GFR stimulate the activity of osteoblasts and upregulate their expression of RANKL. These alterations, more prominent during clinically active NS, are transient and reversible upon remission. These disturbances of bone biology may play an important pathogenic role in the abnormal bone histology observed in patients with NS even before a decline in GFR occurs.

Estrogen receptor (ER) gene polymorphism may predict the bone mineral density response to raloxifene in postmenopausal women on chronic hemodialysis.

The estrogen receptor (ER) gene has been considered as a candidate genetic marker for osteoporosis, and PvuII and XbaI polymorphisms of the ERalpha gene have been associated with low bone mineral density (BMD). We investigated whether ER polymorphism could predict the response of BMD in 28 postmenopausal women on hemodialysis with marked osteopenia or osteoporosis, randomized to receive raloxifene, a selective estrogen receptor modulator (SERM), or placebo for 1 year. BMD was assessed by dual X-ray absorptiometry and PvuII and XbaI restriction fragment-length polymorphism of the ER gene was determined using polymerase chain reaction. Baseline lumbar spine or femoral neck BMD parameters were not different between patients presenting either homozygous PP or xx when compared with heterozygous Pp or Xx genotypes. After 1 year, patients on raloxifene, presenting with PP or xx genotypes (but not those with Pp or Xx), showed a significantly higher mean lumbar spine BMD (0.942 +/- 0.18 vs. 0.925 +/- 0.17 g/cm2, p < .01) and lower serum pyridinoline (19.7 +/- 9.7 vs. 30.6 +/- 16.5 nmol/L, p < .02) when compared with baseline values. No changes were detected in the placebo-treated patients or in the femur neck sites. In conclusion, after 1 year on raloxifene, postmenopausal osteoporotic women on chronic hemodialysis, homozygous for the P or x (PP or xx) alleles of the ER, exhibited a better lumbar spine BMD response and decreased serum pyridinoline values when compared with heterozygous women (Pp or Xx), suggesting that ERalpha allelic variants may explain, at least in part, the different outcomes after treatment of osteoporosis with SERM.

Outcomes associated with hypogonadism in women with chronic kidney disease.

The successful use of renal replacement therapy has resulted in longer survival and a population of older patients with chronic kidney disease (CKD) that includes patients with other significant preexisting illnesses. In this review, we analyze the short-term and long-term outcomes associated to persisting hypogonadism in CKD patients. The short-term manifestations, commonly observed in normal postmenopausal women, are either a rare complaint of women with CKD or are frequently attributed to the uremic state. These symptoms include hot flashes, sleep disturbances and depression, sexual dysfunction, vaginal dryness and atrophy, urinary incontinence, and skin aging and wrinkling. The long-term outcomes of hypogonadism have potentially devastating effects on bone, cardiovascular system, and cognitive function, which could significantly alter the quality of life and survival of women with stage 5 CKD (CKD-5). Postmenopausal osteoporosis has been recognized as an important entity associated with renal osteodystrophy, and efforts have begun to tackle the reduced bone-mineral density (BMD) and increased fracture rate seen in this population. Similarly, cardiovascular disease represents the major cause of death in the CKD-5 population, with a 10 to 20 times greater mortality than in the general population. The accumulating evidence for a possible link between osteoporosis and atherosclerosis is discussed, as well as new directions in the understanding of postmenopausal osteoporosis in the context of renal bone disease, under the guidance of the Global Bone and Mineral Initiative endorsed by the Kidney Disease: Improving Global Outcomes initiative. Nephrologists must face gynecological issues with their women patients and design interdisciplinary clinical studies that include strategies that utilize well-tested and newer drug regimens in the management of osteoporosis, cardiovascular disease, and other postmenopausal manifestations in CKD-5 patients.

Postmenopausal osteoporosis in the dialysis patient.

PURPOSE OF REVIEW: Osteoporosis is the most prevalent bone disorder in the general population, particularly in the middle and older age groups. Although more than half of the prevalent dialysis population is within these age groups, little concern has been given to the possible role of estrogen deficiency in the pathogenesis of bone disease in end-stage renal disease. The purpose of this review is to summarize the recent published evidence that supports a potential role of the postmenopausal state in the pathogenesis of bone disease in end-stage renal disease and their implications for treatment. RECENT FINDINGS: Recent studies have shown that although the risk factors for fracture in end-stage renal disease are similar to the general population, the incidence is three to fourfold higher. The high prevalence of older population, the frequently observed premature amenorrhea and early menopause in dialysis patients may play a role. Similarly, the proportion of end-stage renal disease women receiving hormone replacement therapy is at least three times lower than the general population. Recent evidence on the risk of hormone replacement therapy should caution about its use in end-stage renal disease patients. New evidence suggests that selective estrogen receptor modulators may increase bone mass without significant secondary effects. Other alternatives, such as the use of bisphosphonates, should be considered with caution due to the risk of excessive suppression of bone turnover, worsening or favoring the development of adynamic bone disease. SUMMARY: Osteoporosis should be recognized as an important entity that may modify the current conception of renal osteodystrophy in postmenopausal patients with end-stage renal disease. Further clinical studies are needed in order to propose strategies that may reduce the impact of postmenopausal osteoporosis in the dialysis population.

Selective estrogen receptor modulators in chronic renal failure.

BACKGROUND: In addition to renal osteodystrophy, postmenopausal women on dialysis could be at risk of osteoporosis. Hormone replacement therapy (HRT) could have beneficial effects as well as potentially serious risks, especially in uremic women, due to the pharmacokinetics of estradiol in renal failure. Therapeutic alternatives, such as the selective estrogen receptor modulators (SERMs), have shown the benefits of estrogen on bone and serum lipid levels, without its adverse effects on the breast and endometrium, in nonuremic women. METHODS: Recent data on the effect of the SERM raloxifene in bone and lipid metabolism in osteoporotic postmenopausal women on dialysis is reviewed. Since the estrogen receptor (ER) gene has been suggested as a candidate marker for osteoporosis, we investigated whether ER polymorphism could have predicted the BMD response to raloxifene. RESULTS: Hemodialyzed women on raloxifene demonstrated increased trabecular bone mineral density (BMD) and decreased bone resorption markers. Similarly, LDL-cholesterol values dropped significantly. ER gene polymorphism analysis of baseline BMD parameters did not differ between PP/xx or Pp/Xx groups. Nevertheless, patients on raloxifene with PP/xx genotypes, but not those with Pp/Xx, showed a higher trabecular BMD after one year on treatment, suggesting that homozygous women for P or x alleles of the ER have a better BMD response to raloxifene. CONCLUSION: Raloxifene and, most likely, other SERMs, could represent a good alternative to HRT in postmenopausal uremic women.

Bone remodeling after renal transplantation.

Several studies have indicated that bone alterations after transplantation are heterogeneous. Short-term studies after transplantation have shown that many patients exhibit a pattern consistent with adynamic bone disease. In contrast, patients with long-term renal transplantation show a more heterogeneous picture. Thus, while adynamic bone disease has also been described in these patients, most studies show decreased bone formation and prolonged mineralization lag-time faced with persisting bone resorption, and even clear evidence of generalized or focal osteomalacia in many patients. Thus, the main alterations in bone remodeling are a decrease in bone formation and mineralization up against persistent bone resorption, suggesting defective osteoblast function, decreased osteoblastogenesis, or increased osteoblast death rates. Indeed, recent studies from our laboratory have demonstrated that there is an early decrease in osteoblast number and surfaces, as well as in reduced bone formation rate and delayed mineralization after transplantation. These alterations are associated with an early increase in osteoblast apoptosis that correlates with low levels of serum phosphorus. These changes were more frequently observed in patients with low turnover bone disease. In contrast, PTH seemed to preserve osteoblast survival. The mechanisms of hypophosphatemia in these patients appear to be independent of PTH, suggesting that other phosphaturic factors may play a role. However, further studies are needed to determine the nature of a phosphaturic factor and its relationship to the alterations of bone remodeling after transplantation.

Effects of raloxifene on bone metabolism and serum lipids in postmenopausal women on chronic hemodialysis.

BACKGROUND: Premature amenorrhea and hypoestrogenism and lack of hormone replacement therapy after menopause have been frequently reported in uremic women on dialysis. Therefore, in addition to renal osteodystrophy, postmenopausal women on dialysis could be at risk of osteoporosis. In addition, these patients are at higher risk for hyperlipidemia, arteriosclerosis, and subsequent coronary heart disease and stroke. Recent evidence has suggested that hormone replacement therapy (HRT) in postmenopausal women could have several beneficial effects as well as potentially serious risks. Great efforts have been made to identify therapeutic alternatives that would have the benefits of estrogen on brain and bone without its adverse effects on breast and endometrium. In the present study, we evaluated the effect of raloxifene, a selective estrogen receptor modulator (SERM), on bone metabolism and serum lipids in postmenopausal women on chronic hemodialysis. METHODS: We performed a prospective, blind, placebo-controlled, and randomized study. Fifty postmenopausal women on chronic hemodialysis with proven severe osteopenia or osteoporosis by bone densitometry were selected. After a written informed consent, patients were randomized into two groups: 25 women on placebo and 25 women on the study drug, raloxifene hydrochloride, at a dose of 60 mg/day. In all patients, we performed a baseline bone mineral density (BMD) analysis and simultaneously evaluated different biochemical parameters, serum lipids (total low-density lipoprotein [LDL] and high-density lipoprotein [HDL] cholesterol and triglycerides) and serum markers of bone resorption (pyridinoline crosslinks). BMD was reassessed after 1 year of therapy. Bone resorption markers were determined every 3 months for 1 year. RESULTS: After 1 year on raloxifene therapy, lumbar spine BMD (trabecular bone) significantly improved, whereas femoral neck BMD (cortical bone) did not change significantly. No changes in BMD were observed at trabecular or cortical sites in the placebo group. Serum pyridinoline levels showed a significant decrease after 6 months on raloxifene that persisted thereafter. Low-density lipoprotein (LDL)-cholesterol decreased significantly in the raloxifene group with no changes in serum triglycerides, total cholesterol, or HDL cholesterol. No significant side effects were observed in the raloxifene group. CONCLUSION: The study demonstrates that after one year on raloxifene, postmenopausal women on hemodialysis have a significant increase in trabecular BMD, decrease in bone resorption markers and LDL-cholesterol values, suggesting that SERMs could constitute a therapeutic alternative to improve bone metabolism and control of hyperlipidemia in these patients. The possible long-term effects of raloxifene remain to be determined.

The pathogenesis of osteodystrophy after renal transplantation as detected by early alterations in bone remodeling.

BACKGROUND: Loss of bone mass after transplantation begins in the early periods after transplantations and may persist for several years, even in patients with normal renal function. While the pathogenesis of these abnormalities is still unclear, several studies suggest that preexisting bone disease, glucocorticoid therapy, and alterations in phosphate metabolism may play important roles. Recent studies indicate that osteoblast apoptosis and impaired osteoblastogenesis play important roles in the pathogenesis of glucocorticoid-induced osteoporosis. OBJECTIVES: To examine the early alterations in osteoblast number and surfaces during the period following renal transplantation. METHODS: Twenty patients with a mean age of 36.5 +/- 12 years were subjected to bone biopsy 22 to 160 days after renal transplantation. In 12 patients, a control biopsy was performed on the day of transplantation. Bone sections were evaluated by histomorphometric analysis and cell DNA fragmentation by the methods of terminal deoxynucleotidyl transferase-mediated uridine triphosphate nick end labeling (TUNEL), using immunoperoxidase and direct immunofluorescence techniques. RESULTS: The main alterations in posttransplant biopsies were a decrease in osteoid and osteoblast surfaces, adjusted bone formation rate, and prolonged mineralization lag time. Peritrabecular fibrosis was markedly decreased. None of the pretransplant biopsies revealed osteoblast apoptosis. In contrast, TUNEL-positive cells in the proximity of osteoid seams or in the medullary space were observed in nine posttransplant biopsies of which four had mixed bone disease, two had adynamic bone disease, one had osteomalacia, one had osteitis fibrosa, and one had mild hyperparathyroid bone disease. Osteoblast number in posttransplant biopsies with apoptosis was lower as compared with posttransplant biopsies without apoptosis. In addition, most of them showed a marked shift toward quiescence from the cuboidal morphology of active osteoblasts. Serum phosphorus levels were lower in patients showing osteoblast apoptosis and correlated positively with osteoblast number and negatively with the number of apoptotic osteoblasts. In addition, posttransplant osteoblast surface correlated positively with parathyroid hormone (PTH) levels and negatively with glucocorticoid cumulative dose. CONCLUSION: The data suggest that impaired osteoblastogenesis and early osteoblast apoptosis may play important roles in the pathogenesis of posttransplant osteoporosis. The possible mechanisms involved in the pathogenesis of theses alterations include posttransplant hypophosphatemia, the use of glucocorticoids, and the preexisting bone disease. PTH seems to have a protective effect by preserving osteoblast survival.

Abnormalities of bone mineral density and bone metabolism in Venezuelan patients with rheumatoid arthritis.

Patients with rheumatoid arthritis (RA) are at increased risk for osteoporosis and bone fractures. To our knowledge, the frequency of osteopenia and osteoporosis in patients with RA from Latin America has not been established. In this study, we have examined the bone mineral density (BMD) by dual-energy x-ray absorptiometry, as well as biochemical markers of bone metabolism, in a population of 85 Venezuelan RA patients. Twenty-seven patients (29.4%) fulfilled the World Health Organization's (WHO) criteria for either trabecular osteopenia or osteoporosis compared with 10 healthy controls (8.1%; odds ratio [OR] = 3.25; P = 0.004). In addition, 30 patients (26.4%) showed cortical osteopenia or osteoporosis compared with 5 healthy controls (4.0%; OR = 8.18; P < 0.00001). Past or concurrent use of prednisone or methotrexate was not related to decreased BMD. Rheumatoid patients showed increased serum levels of osteocalcin (P = 0.002) and 24-hour urine excretion of N-telopeptide cross-links (P = 0.03). The bone marker profiles suggest an increased bone turnover during the premenopausal stage in these patients. After menopause, a resorptive pattern seems to predominate, leading to accelerated bone mass loss in RA patients. In conclusion, Venezuelan female patients with RA may be at increased risk for osteopenia or osteoporosis, particularly after menopause. Our study supports the initiation of antiresorptive medication in Latin American premenopausal patients with RA, as in other ethnic groups, to diminish the risk of osteoporosis in the postmenopausal stage.

The effect of short- and long-term growth hormone treatment on bone mineral density and bone metabolism of prepubertal children with idiopathic short stature: a 3-year study.

OBJECTIVE: We recently reported that children with idiopathic short stature (ISS) have decreased lumbar spine bone mineral density (BMD) that increases after 1 year of GH therapy. The aim of this study was to confirm these short-term results and to evaluate the effect of long-term GH therapy on the BMD of children with ISS. PATIENTS AND DESIGN: We treated a group of 16 short, slow-growing but otherwise healthy non-GH-deficient prepubertal children (8 girls and 8 boys) with a chronological age of 9.5 +/- 0.9 years, a bone age of 8.1 +/- 1.2 years and a height of 124.3 +/- 6.3 cm (height-SDS of -2.1 +/- 0.6) with GH at a dose of 0.1 IU/kg/day for 3 consecutive years. MEASUREMENTS: Height was determined at 3-month intervals and annual growth velocities were calculated. Bone ages and BMD were measured every 12 months by dual-energy X-ray absorptiometry, as were serum concentrations of the carboxy-terminal propeptide of type 1 collagen (PICP) and the carboxy-terminal cross-linked telopeptide of type 1 collagen (ICPT). RESULTS: Growth velocity increased from 4.0 +/- 0.8 cm/year to 8.7 +/- 1.5 and 8.0 +/- 1.7 cm/year at 12 and 36 months of GH therapy, respectively, while height-SDS improved from -2.1 +/- 0.6 to -1.6 +/- 0.4 after 36 months of GH (P < 0.0001). Baseline lumbar spine BMD was decreased when compared to that of a control group of healthy children paired for gender, bone age and height (0.640 +/- 0.08 g/cm2vs. 0.730 +/- 0.08 g/cm2; P < 0.003). Lumbar spine BMD increased after 1 year of GH from 0.640 +/- 0.08 to 0.749 +/- 0.08 g/cm2 (P < 0.05), reaching levels similar to that of controls followed for 1 year without therapy (0.749 +/- 0.04 g/cm2vs. 0.760 +/- 0.08 g/cm2). During this period lumbar spine BMD increased 14.5% in the ISS subjects and 3.9% in the controls. Over the following 2 years of GH therapy the lumbar spine BMD of our ISS patients increased at a rate similar to that of the control population, so that after 3 years of consecutive GH therapy the lumbar spine BMD of ISS children was comparable to that of the controls (0.784 +/- 0.12 g/cm2vs. 0.785 +/- 0.09 g/cm2). Femoral neck BMD of our patients was similar to that of the controls at baseline and at 36 months. Following 1 year of GH treatment serum concentrations of PICP increased from 229.6 +/- 63.5 to 358.6 +/- 87.9 micro g/l, while levels of ICTP increased from 9.6 +/- 5.9 to 13.7 +/- 2.1 micro g/l. After 36 months of GH therapy, PICP and ICTP values had decreased to 303.3 +/- 67.2 micro g/l and 11.3 +/- 3.3 micro g/l, respectively, and were no longer significantly different from baseline. CONCLUSIONS: Children with ISS have decreased lumbar spine BMD, which normalized after 1 year of GH. Over the next 2 years of therapy lumbar spine BMD increased at a normal rate, so that after 3 consecutive years of GH the lumbar spine BMD of children with ISS was similar to that of controls. Bone turnover increased with treatment as indicated by a rise in bone formation and bone resorption markers.

Reduced bone mass in children with idiopathic hypercalciuria and in their asymptomatic mothers.

BACKGROUND: Patients with nephrolithiasis and idiopathic hypercalciuria (IH) may exhibit reduced bone mineral density (BMD). Most studies measuring BMD in IH patients employing dual-energy X-ray absorptiometry (DEXA) have been performed in adults, and no study has been conducted in North-American children. Optimal bone mineral accretion during childhood and adolescence is critical to the attainment of a healthy adult skeleton. Bone mineral accretion and eventual adult peak bone mass are largely dependent on genetic factors. Hypercalciuria is also frequently linked to genetic determinants. Therefore, we carried out a cross-sectional evaluation of bone mineral metabolism in children with IH, and in their asymptomatic premenopausal mothers. METHODS: Quantitative BMD using DEXA was performed in 21 children with IH and in their asymptomatic mothers. Bone resorption was assessed by measuring the urinary concentrations of pyridinoline and deoxypiridinoline. Simultaneous calcium-modulating hormonal determinations, including serum intact immunoreactive parathyroid hormone and 1,25(OH)(2)D(3), were performed. The expression of interleukin-1alpha (IL-1alpha) by peripheral blood mononuclear cells (PBMCs) was determined by polymerase chain reaction. RESULTS: Reduced BMD values were observed in eight children (38%) and in seven mothers (33%). The children of osteopenic mothers exhibited significantly reduced BMD Z-score values of lumbar spine (P<0.05) when compared with children of mothers with normal BMD. Bone resorption markers were normal in most children with IH. Hypercalciuria was detected in five out of 20 (25%) asymptomatic mothers and it correlated (r=-0.81) to femoral BMD in mothers with osteopenia. The expression of IL-1alpha mRNA by PBMCs from IH children did not differ from controls. CONCLUSIONS: Reduced BMD was detected in a large proportion of children with IH. Hypercalciuria and reduced BMD were uncovered in a substantial number of their otherwise healthy asymptomatic mothers. The diminished BMD in adults with IH may start early in life, could be influenced by genetic factors, and may represent a risk factor for osteoporosis later in life.