Post-Renal Transplantation Bone Health in Children Evaluated by Means of Quantitative Ultrasound and Densitometry.

BACKGROUND: Patients with end-stage renal disease develop bone mineral disease, which is not always resolved after a successful renal transplantation; moreover, some of the immunosuppressants used to prevent graft rejection may affect bone health. The aim of this study was to evaluate bone health in post-renal transplantation children with the use of quantitative ultrasound (QUS) and dual-energy X-ray absorptiometry (DXA). METHODS: A descriptive study was performed in children >3 months after renal transplantation and with stable function of graft. Radial QUS and DXA (lumbar spine and total body less head (TBLH) were performed on the same day. RESULTS: A total of 35 patients were included. Mean age was 13.9 ± 3.9 years. Ten subjects had total bone density score <2 (28.5%), 4 a lumbar spine (L1-L4) Z-score of <2 (11.4%) as well as TBLH <2, and 6 subjects had a radial QUS Z-score of <2 (17.1%), and only 2 of them had concomitant Z-score <2 with the use of DXA. There was a positive non-significant correlation between TBLH and radial QUS Z-scores (Pearson r = 0.317; P = .016) and a positive significant correlation of DXA lumbar spine and radial QUS Z-scores (Pearson r = 0.452; P = .014). CONCLUSIONS: Despite a good correlation between TBLH and QUS Z-scores, there are subjects that can be considered normal by QUS and have osteopenia by TBLH DXA and vice versa; this could be due to the different bone areas evaluated.

Prostaglandin E1 increases in vivo and in vitro calcitriol biosynthesis in rabbits.

INTRODUCTION: Prostaglandins have an anabolic effect on bone. Possible mediation of this effect is via calcitriol. This study determines in vivo and in vitro effects of PGE(1) on calcitriol synthesis. METHODOLOGY: In vivo: rabbits received intravenous vehicle or prostaglandin E(1) (50 microg/day) for 20 days before measurements of serum total and ionic calcium, magnesium and phosphorus levels, total and bone-specific alkaline phosphatases, 25(OH)D(3), calcitriol, parathyroid hormone and calcitonin. In vitro: rabbit proximal renal tubules were incubated with 25(OH)D(3) (8 microM) together with PGE(1) (2.82 x 10(-6) M) and the prostaglandin receptor inhibitor AH6809 (10(-4) M) in selected samples. After 5 or 30 min incubation, calcitriol production was measured by radioimmunoassay and data analysed statistically. RESULTS: In vivo, in groups receiving PGE(1), levels of total Ca, Mg and calcitriol increased significantly and 25 dihydroxyvitamin D(3), parathyroid hormone and calcitonin remained unchanged. In vitro, PGE(1) increased calcitriol biosynthesis and the prostaglandin inhibitor AH6809 reduced calcitriol levels significantly after prolonged incubation. CONCLUSIONS: In vivo and in vitro results demonstrate that PGE(1) stimulates calcitriol synthesis. This study represent a major advancement in knowledge of bone metabolism.

Síndrome de exceso de prostaglandina E, en conejos / Hyperprostaglandin E syndrome in rabbits

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Secondary hyperparathyroidism in chronic renal failure: pathogenic and clinical aspects.

Secondary hyperparathyroidism occurs early in the course of chronic renal failure. Early in the course, a deficit of calcitriol and an abnormality in the calcium sensor receptor may be the important factors; later, with advanced renal failure, hyperphosphatemia becomes an additional important pathogenic factor. Important clinical problems in dialysis patients are as follows: (1) hyperphosphatemia, which contributes to high morbidity and mortality of dialysis patients (a clinical approach to maintaining a normal serum phosphorus is essential and is discussed in this review); (2) a high calcium X phosphorus product leading to coronary artery calcifications (factors leading to calcifications are also discussed); and (3) calciphylaxis, which has been observed with increasing frequency in these patients (an increase in the total calcium load may be the most important pathogenic factor leading to this syndrome). Therapeutic considerations regarding the use of new vitamin D analogues devoid of a hypercalcemic and/or a hyperphosphatemic effect are also mentioned.

High frequency of iron bone deposits in a Mexican population with renal osteodystrophy.

Renal osteodystrophy (ROD) is a multifactorial disease. Aluminium deposits have been implicated in its physiopathology but iron deposits have seldom been described. The purpose of this study was to investigate the presence of iron on the mineralization front, in 70 patients with ROD. Their mean age was 48+/-16 years, 36 were female, 34 male, 55 were admitted on peritoneal dialysis (78.5%) and 15 to haemodialysis (21.5%), for a period of 28+/-22 months. A bone biopsy was obtained from each patient after double tetracycline labelling. Blood samples were also obtained at the time of bone biopsy. The histomophometric analysis was performed following the criteria of Sherrard et al., with slight modifications; beside the usual stains, aluminium, iron and amyloid stainings were done on all bone specimens. Biochemical findings were: Ca 8.8+/-0.9 mg/dl, P 6.1+/-1.5 mg/dl; total alkaline phosphatase 197+/-258; PTHm 4.9+/-4.05ng/ml (normal 0.4-0.7 ng/ml), calcitonin 11+/-6 pg/ml (normal 1-26 pg/ml). Osteitis fibrosa was found in 31 patients (44.28%), mixed bone disease in two patients (2.28%); mild bone disease in 20 subjects (28.57%), adynamic bone lesion in 15 cases (21.42%) and osteomalacia in two patients (2.28%). Iron deposits were found on the mineralization front in 43 patients (61.4%); in 17, the percentage was <25 and, in 26, >25%. The iron deposits in the osteitis fibrosa group were highly significant (25/31). The aluminium deposit at the mineralization front was observed in eight patients (11.4%); in all but one, the percentage of this metal was <10%. Amyloid deposits were negative in all cases. The results show: (i) a Mexican population with ROD, present a highly significant incidence of siderosis on the bone mineralization front; (ii) in contrast, the aluminium deposits in this group of patients is lower than that reported in other series, and (iii) the spectrum of RO in this Mexican population is similar to that reported in other studies.

Adynamic bone lesion in renal transplant recipients with normal renal function.

Adynamic bone lesion has been defined as low bone turnover, normal or low osteoid volume and decreased bone formation rate (BFR). A prospective cross-sectional study was performed in 16 asymptomatic post-transplant kidney patients with normal renal function, to evaluate low bone mineral density. The mean age of the nine women and seven men was 33.9 +/- 7.3 years, the mean serum creatinine was 1.1 +/- 0.2 mg/dl and the mean creatinine clearance 71.5 +/- 13.8 ml/min/1.73 m2. Six patients received triple immunosuppressive therapy for a period of 10.3 +/- 3.7 months and nine received double therapy. Eighty-four months after renal grafting, we carried out bone densitometry, biochemical markers and bone biopsy. Bone densitometry showed 78 +/- 8.7% and 80.4 +/- 8% for hip and lumbar spine, with a mean Z score of 1.79 +/- 0.72 and 1.88 +/- 0.78 (SD), significantly less than normal in the Hispanic young population for those two regions. Serum PTH (0.83 +/- 0.23 microgram/ml normal range 0.32-0.65), urine cAMP (4.1 +/- 1.3, normal range 0.5-4.7 nmol/mg Cr) and total and nephrogenic fraction (3.1 +/- 1.1, normal range 0.29-2.9 nmol/100 ml GFR) were significantly greater than normal (P < 0.01). The bone biopsy in 12/16 patients showed decreased percentage osteoid area (1.59 +/- 0.86% vs 3.19 +/- 0.82%), percentage mineralized area (13 +/- 4.7% vs 21.03 +/- 3.36%) and bone formation rate (505 +/- 237 vs 1275 +/- 168 microns2/mm2/day), with a P value < 0.05 compared with 10 normal bone biopsies. The remaining four patients exhibited low bone turnover image with normal bone formation rate (1442 +/- 206 microns2/mm2/ day). Iron deposits were demonstrated at the mineralization front in 10/16 patients. No aluminium or amyloid deposits were observed. The histomorphometric results showed the presence of adynamic bone lesion in 12 renal transplant recipients with normal renal function and osteopenia, which explains the low bone density. The long-term use of glucocorticoids and the presence of iron deposits may contribute to this bone lesion. The biochemical markers of bone remodelling showed abnormalities compatible with moderate increase in parathyroid function. The adynamic lesion in the presence of hyperparathyroid function may suggest down-regulation of PTH bone receptors, alterations of the bone microenvironment or both.

Renal transition forms in lupus nephritis: clínico-pathological correlations

Con el objeto de conocer la frecuencia de las transiciones histológicas desarrolladas en nuestros pacientes con Lupus Eritematoso Sistémico, sometidos a un tratamiento terapéutico similar, se practicó una segunda biopsia en 30 pacientes en un intervalo promedio de 34 meses. Todas las biopsias fueron histológicamente clasificadas siguiendo los criterios propuestos por la Organización Mundial de la Salud. Se analizó el valor pronóstico de los índices de actividad, cronicidad, de los hallazgos de inmunofluorescencia y de microscopía electrónica en las biopsias iniciales como marcadores de las transformaciones histológicas. De los 30 pacientes estudiados, 11 exhibieron transiciones histológicas en la segunda biopsia renal (36% ), de éstos, 4 se encontraban en grupo histológico de "Alto Riesto" (Clase III y IV) y 7 en el de "Bajo Riesto" (Clase I,II, V), en sus biopsias iniciales. Las transiciones histológicas observadas en las segundas biopsias de estos pacientes, no se pudieron predecir en base a su grado clínico inicall, evolución o hallazgos histológicos en las primeras biopsias.

Idiopathic nephrotic syndrome of the adult with asymptomatic thrombosis of the renal vein.

Twenty-six adult patients with idiopathic nephrotic syndrome, ages ranging from 16 to 62 years, were prospectively evaluated with selective renal venogram for the presence of renal vein thrombosis (RVT). Ten patients had membranoproliferative glomerulonephritis (MPGN); 5, membranous nephropathy (MGN); 3, diffuse proliferative glomerulonephritis (DGPG), and 1 focal glomerulonephritis (FPG). Renal vein thrombosis was observed in 11 patients. The primary nephropathies in these patients were: MPGN in 4, MGN in 3, FGS in 2, FPG in 1, and DGPG in 1. All patients were asymptomatic. The clinical and renal pathology features were similar in patients with and without RVT. Other thromboembolic complications were observed in 4 patients. In conclusion, renal vein thrombosis was observed in 42% of our patients and MPGN was the most frequent nephropathy associated with RVT.

[Idiopathic membranous glomerulonephritis]. / Glomerulonefritis membranosa idiopática.

The only case of idiopathic membranous glomerulonephritis seen out of 106 nephropathic patients biopsied in the two last years at the C. H. 20 de Noviembre, I.S.S.S.T.E., is reported. Twenty-six showed nephrotic syndrome not associated to systemic disease, including the present case, which gave us an incidence of 3.8% of this entity. We were impressed by the low frequency of this disease, so we made a statistical epidemiological analysis localizing it geographically based on the available medical literature. On comparing the results of these studies we confirmed that this disease is significantly low in our environment.