Alterations of bone microstructure and strength in end-stage renal failure.

UNLABELLED: End-stage renal disease (ESRD) patients have a high risk of fractures. We evaluated bone microstructure and finite-element analysis-estimated strength and stiffness in patients with ESRD by high-resolution peripheral computed tomography. We observed an alteration of cortical and trabecular bone microstructure and of bone strength and stiffness in ESRD patients. INTRODUCTION: Fragility fractures are common in ESRD patients on dialysis. Alterations of bone microstructure contribute to skeletal fragility, independently of areal bone mineral density. METHODS: We compared microstructure and finite-element analysis estimates of strength and stiffness by high-resolution peripheral quantitative computed tomography (HR-pQCT) in 33 ESRD patients on dialysis (17 females and 16 males; mean age, 47.0 ± 12.6 years) and 33 age-matched healthy controls. RESULTS: Dialyzed women had lower radius and tibia cortical density with higher radius cortical porosity and lower tibia cortical thickness, compared to controls. Radius trabecular number was lower with higher heterogeneity of the trabecular network. Male patients displayed only a lower radius cortical density. Radius and tibia cortical thickness correlated negatively with bone-specific alkaline phosphatase (BALP). Microstructure did not correlate with parathyroid hormone (PTH) levels. Cortical porosity correlated positively with "Kidney Disease: Improving Global Outcomes" working group PTH level categories (r = 0.36, p < 0.04). BMI correlated positively with trabecular number (r = 0.4, p < 0.02) and negatively with trabecular spacing (r = -0.37, p < 0.03) and trabecular network heterogeneity (r = -0.4, p < 0.02). Biomechanics positively correlated with BMI and negatively with BALP. CONCLUSION: Cortical and trabecular bone microstructure and calculated bone strength are altered in ESRD patients, predominantly in women. Bone microstructure and biomechanical assessment by HR-pQCT may be of major clinical relevance in the evaluation of bone fragility in ESRD patients.

[Acute renal colic: which radiological exam in the GP daily practice?]. / Colique néphrétique au cabinet: quel bilan radiologique pour quel patient?

Nephrolithiasis is a common disease. Acute renal colic due to migration of stone is a frequent cause of admission in emergencies departements (ED). Diagnostic procedures in such centers are already well codified. This article discuss the diagnostic management and particularly the question of the radiological evaluation in patients presenting with renal colic to the general practitioner (GP). Because of the high risk of recurence and in order to identify patients with high stone burden, every patient presenting a first episode of renal colic should undergo radiological investigation. Considering sensitivity, irradiation rate, cost and diagnostic information, we recommend the (low-doses CT-SCAN as exam of choice for initial radiological evaluation of patient with renal colic.

[Vitamin D treatment--which analogs and when?]. / Substitutionsbehandlung mit Vitamin D--für welche Patienten und welche Analoga?

Chronic kidney disease is associated with a decreased production of the active metabolite of vitamin D, 1 alpha,25-Dihydroxy-Vitamin D. This decrease has several consequences which are not only restricted to the bones. Indeed, vitamin D has multiple actions which are discussed in this review. Vitamin D substitution is considered early in the treatment of chronic kidney disease but uncertainties about the type of substitution remain. The role of vitamin D analogs are reviewed with emphasis on the comparison between calcitriol and paricalcitol.

Hypercalcemia and hyperosteolysis in vitamin D intoxication: effects of clodronate therapy.

Vitamin D intoxication is a rare cause of hypercalcemia, which is associated with severe and prolonged morbidity. Hypercalcemia and/or hypercalciuria are the consequence of increases in both intestinal absorption and bone resorption. We report on 7 cases of vitamin D overdose (25-hydroxyvitamin D: 710 +/- 179 nmol/l; normal range: 20-90). The indications for vitamin therapy were osteoporosis (5), hypoparathyroidism (1), and osteomalacia (1). Enhanced bone resorption was demonstrated by increased fasting urinary calcium excretion (0.192 +/- 0.067 mmol/l GFR, normal < 0.045). Sequential biochemical measurements in the hypoparathyroid patient showed the persistence of abnormally elevated fasting urinary calcium and of serum 25-hydroxyvitamin D concentrations, even after normalization of plasma calcium, emphasizing that enhanced bone resorption is a prominent feature of vitamin D action. The intravenous administration of a single infusion of the bisphosphonate clodronate to 3 patients led to a correction of hypercalcemia/hypercalciuria, whereas prednisone therapy given to 2 other cases barely affected the abnormal biochemical values. These results indicate that enhanced bone resorption encountered in vitamin D intoxication could be favorably influenced by bisphosphonate treatment.

Effects of dialysate composition during hemodialysis on left ventricular function.

To determine the effects of dialysate composition during hemodialysis on left ventricular systolic and diastolic function, 12 patients treated by chronic hemodialysis (mean age 40.8 +/- 2.7 years), without overt heart disease, were studied by Doppler-echocardiography successively before and after acetate hemodialysis (AHD), bicarbonate hemodialysis (BHD), and acetate-free biofiltration (AFB). The three types of hemodialysis resulted in a comparable decrease of the body weight. Mean arterial blood pressure decreased by 5 mm Hg (NS), 8 mm Hg (NS) and 10 mm Hg (P < 0.05) during AHD, BHD and AFB, respectively. There was a significant increase of the heart rate and the shortening fraction of the left ventricular diameter after AHD, but not after BHD and AFB. Mean total systemic resistance increased by 20% after AHD, 18% after BHD and by 7% after AFB (all changes NS). During each type of hemodialysis there was a significant reduction of the peak velocity of the early diastolic rapid filling wave (peak E) without change of the peak filling velocity during atrial contraction (peak A). During AHD and BHD the pressure half-time of the early filling phase (TP/2) increased, and the velocity-integral of the early diastolic filling phase (E-area) decreased. However, TP/2 and E-area did not change significantly after AFB.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of altered loading conditions during haemodialysis on left ventricular filling pattern.

Changes in the circulating volume associated with haemodialysis result in modification of left ventricular loading conditions. To determine the influence of haemodialysis on Doppler indices of left ventricular filling, 12 patients (mean age 40.8 +/- 2.7 (SEM) years) with renal insufficiency but without overt heart disease were studied by Doppler-echocardiography immediately before and after haemodialysis. Haemodialysis resulted in a decrease in body weight from 68.0 +/- 3.8 kg to 65.0 +/- 3.7 kg (P < 0.01). Heart rate and blood pressure did not change significantly during haemodialysis. Left ventricular diastolic dimension (M-mode) decreased from 53.5 +/- 1.1 mm to 49.5 +/- 1.9 mm (P < 0.05), whereas the shortening fraction did not change. Haemodialysis elicited marked changes in the early diastolic rapid filling wave (E wave) recorded by pulsed Doppler at the level of the mitral annulus. Peak velocity of the early rapid filling phase (peak E) decreased significantly from 95.3 +/- 8.2 cm.s-1 to 63.0 +/- 5.7 cm.s-1 (P < 0.001) and mid-diastolic deceleration of transmitral velocity decreased from 437.3 +/- 54.2 cm.s-2 to 239.7 +/- 54.4 cm.s-2 (P < 0.01). The peak filling velocity during atrial contraction (peak A) did not change (79.7 +/- 6.3 cm.s-1 vs 74.1 +/- 4.7 cm.s-1; P = NS). The ratio peak E/peak A decreased from 1.19 +/- 0.06 to 0.85 +/- 0.04 (P < 0.01) during haemodialysis. The results provide further evidence for the pronounced preload-dependence of Doppler indices of left ventricular diastolic function.

Hemostatic disturbances induced by two hollow-fiber hemodialysis membranes.

The effects on hemostasis of two high-flux membranes in hollow-fiber configuration, polyamide (PAM) and polyacrylonitrile (AN69), were analyzed in a cross-over study involving ten chronic hemodialyzed patients. Blood samples were obtained at arterial and venous sites of the extracorporeal circuit before dialysis and at 15, 30 and 180 min. Primary hemostasis: PAM induced an early significant drop in platelet counts, but at 180 min there was no longer any difference between membranes. Beta-thromboglobulin release by PAM was significantly higher at all time points. Coagulation: thrombin-antithrombin III complexes (TAT) and fibrinopeptide A increased significantly, the highest values being found with AN69. With both membranes the arterio-venous differences in TAT levels were negative throughout the sessions. Fibrinolysis: no significant differences were observed. In conclusion, both membranes induced hemostatic changes. Although these two hollow-fiber dialyzers look relatively similar, the changes observed were different, polyamide acting mainly on primary hemostasis and polyacrylonitrile on coagulation.