C282Y hemochromatosis gene mutation and iron parameters in dialysis patients.

BACKGROUND: Hereditary hemochromatosis is an autosomal recessive condition causing excessive intestinal iron absorption related to C282Y hemochromatosis mutation gene. Dialysis patients receive intravenous iron supplements as treatment for anemia. The gene mutation frequency and its influence on iron deposits and intravenous iron response are unknown in these patients. STUDY DESIGN: Prospective observational. SETTING AND PARTICIPANTS: 290 dialysis patients in Gran Canaria, Spain. OUTCOMES AND MEASUREMENTS: The C282Y hemochromatosis mutation gene was studied. Other active players in iron metabolism have not been included in this study. Red cell parameters, serum iron, transferrin and ferritin concentrations were measured every 2 months for 2 years. RESULTS: No differences in allelic and genotypic frequencies between dialysis patients and the general population were detected. Baseline clinical or analytical parameters were similar in C282Y +/- and C282Y -/- patients. Among those who did not need intravenous iron treatment, C282Y+/- patients maintained constant serum ferritin (302.1 ± 216.7 vs. 319.5 ± 300.5 µg/l after 4 months), whereas C282Y-/- patients showed decreased levels during the same period (306.7 ± 212.2 vs. 221.6 ± 167.8 µg/l, p < 0.001). After 4 months of parenteral iron, serum ferritin increased more intensely in C282Y +/- patients than in C282Y -/- patients (934.2 ± 195.8 vs. 658.7 ± 259.9 µg/l, p < 0.001). A multivariance analysis identified the C282Y allele as the most important factor that explains this difference. CONCLUSIONS: Heterozygosity for the C282Y allele of the hemochromatosis mutation gene could be associated with differences in iron parameters in dialysis patients.

Diagnosis of iron deficiency in chronic renal failure.

The cause of anemia in chronic renal failure is multifactorial. Decreased erythropoietin (EPO) production is the main pathogenetic factor, but iron deficiency is the primary cause of unresponsiveness to EPO therapy. The diagnosis of iron deficiency in patients with chronic renal failure is difficult. We assessed the sensitivity and specificity of serum ferritin, total iron-binding capacity, transferrin saturation index, erythrocyte ferritin, and serum transferrin receptor in 63 patients with chronic renal failure undergoing dialysis (47 men, 16 women) with iron deficiency anemia. They were selected on the basis of clinical stability and absence of factors that may interfere with iron metabolism. None of the patients had received intravenous iron therapy or recombinant human erythropoietin (rHuEPO). Bone marrow biopsy with iron staining was the reference standard for iron stores. The receiver operating characteristic (ROC) curve and the area under the curve were calculated to assess the sensitivity and specificity of iron metabolism parameters. The parameter with the largest area under the ROC curve was serum ferritin (0.83). A cut point of 121 microgram/L showed a sensitivity and a specificity of 75%. The areas under the ROC curves of serum transferrin receptor and erythrocyte ferritin were 0.69 and 0.68, respectively. The remaining parameters showed areas under the ROC curve less than 0.65. Although serum transferrin receptor and erythrocyte ferritin may be acceptable markers for iron deficiency in stable chronic renal failure patients, serum ferritin level continues to be the most reliable diagnostic parameter. Transferrin saturation index is not a reliable parameter for the diagnosis of iron deficiency in stable patients not treated with rHuEPO.

Adequacy of dialysis in automated peritoneal dialysis: a clinical experience.

OBJECTIVES: To compare the peritoneal clearances of urea and creatinine in continuous ambulatory peritoneal dialysis (CAPD) with three types of automated peritoneal dialysis (APD): continuous cycling peritoneal dialysis (CCPD), 50% tidal peritoneal dialysis (TPD), and 25% TPD and to assess the usefulness of the peritoneal equilibration test (PET) in predicting peritoneal clearances in overnight APD. PATIENTS: Eleven uremic patients (mean age 44.5 +/- 15.45 years with a mean time on dialysis of 42.63 +/- 25.62 months) were included in the study. MEASUREMENTS: PET for urea and creatinine following Twardowski's method. Peritoneal clearances for urea and creatinine CAPD: samples of blood and dialysate within 24 hours. APD: blood mean levels of urea and creatinine before and after nighttime dialysis. Dialysate: urea and creatinine in nocturnal and daytime dialysate. RESULTS: Peritoneal clearance of creatinine was 38.14 +/- 9.99 L/week/1.73 m2 in CAPD, 44.28 +/- 12.4 L/week/1.73 m2 in CCPD, 50.07 +/- 17.86 L/week/1.73 m2 in 50% TPD (p < 0.05) and 40.18 +/- 6.65 L/week/1.73 m2 in 25% TPD. Peritoneal clearance of urea improved significantly in the three modalities of APD: 51.91 +/- 12.58 L/week/1.73 m2 in CAPD; 66.7 +/- 9.9 L/week/1.73 m2 in CCPD (p < 0.05); 76.3 +/- 14.5 L/week/1.73 m2 in 50% TPD (p < 0.001) and 64.4 +/- 11.4 L/week/1.73 m2 in 25% TPD (p < 0.05). The dialysate/ plasma (D/P) ratio of creatinine at 30, 60, 120, 180, and 240 minutes showed significant correlation with nighttime APD clearance. Nevertheless, only the D/P ratio of urea at 30, 60, and 120 minutes correlated with overnight APD clearance. CONCLUSIONS: A remarkable improvement was observed with APD regarding the clearance of urea mainly when 50% tidal peritoneal dialysis was used, whereas it was less noticeable in the clearance of creatinine. The PET is a helpful tool in predicting overnight peritoneal clearances of creatinine but it is less useful in predicting urea clearance.

[The long-term results on arterial pressure and kidney function after the percutaneous transluminal dilatation of renal artery stenosis]. / Resultados a largo plazo sobre la presión arterial y la función renal después de la dilatación transluminal percutánea de la estenosis de la arteria renal.

BACKGROUND: The purpose of this study was to evaluate the clinical results analyzing the cure, improvement and failure rates of percutaneous transluminal angioplasty (PTA) in patients with the diagnosis of renovascular hypertension with special reference to those with atherosclerotic vascular disease, according to their age, and their effect on blood pressure control and renal function. PATIENTS AND METHODS: In 93 hypertensive patients with a mean age of 43.4 years 123 renal artery PTA were performed: Twenty-six patients older than 50 years and eleven with 50 years or less had atherosclerosis, 27 fibromuscular dysplasia and a mixed disease was found in one patient. Twenty-eight patients with renal transplant were diagnosed as having arterial graft stenosis. RESULTS: After renal PTA, there was a significant decrease in blood pressure in all cases. Patients with atherosclerotic renal vascular disease showed a decrease in systolic pressure (SP) from 168 +/- 19 before PTA to 154 +/- 8 mmHg at 96 months (p < 0.001) and diastolic (DP) from 113 +/- 10 before PTA to 90 +/- 4 mmHg at 96 months (p < 0.001) respectively after the procedure. Significant differences were also observed in patients with fibromuscular dysplasia. Most patients with renal transplant arterial stenosis had less than five years of follow-up and SP and DP decreased from 162 +/- 18 and 109 +/- 8 mmHg before PTA, to 147 +/- 10 (p < 0.001) and 91 +/- 7 mmHg (p < 0.001) at 12 months after dilation respectively. Clinical improvement was achieved in 91% of patients with atherosclerosis at 96 months and fifty percent of the patients with fibromuscular dysplasia were cured after the same period from the time of PTA. Twelve months after the renal transplant artery dilation was achieved a clinical improvement in 81% and a cure rate in 6% of the patients. Ostial lesions comprised the majority of blood pressure benefit failures. There was no significant improvement in renal function immediately after renal artery dilation except in those patients with fibromuscular dysplasia. Residual stenosis greater than 75% was present in 15 patients after the first PTA. Complications were seen in 4.8% and were related to renal failure and vessel dissection. CONCLUSION: Angioplasty is effective in the long-term management of high arterial blood pressure and may preserve renal function according to renal artery disease.