Calcium lactate interference in measuring creatinine in peritoneal dialysis fluids by the Jaffé kinetic method.

Creatinine measurements in peritoneal dialysis fluids using the Jaffé method have poor specificity due to interfering substances. We have checked to see if calcium lactate, in addition to glucose, interferes with the Jaffé kinetic measurement. Eight samples were prepared with increasing concentrations of glucose (960-3890 mg/dL) and eight were prepared with the same glucose content plus 7 mg/dL of calcium lactate, all without creatinine; in addition, 96 samples with increasing concentrations of glucose (1500-4000 mg/dL), calcium lactate (3-7.5 mg/dL), and creatinine (0.75-4.5 mg/dL) were prepared. There was a 0.31 +/- 0.13 mg/dL glucose interference on the Jaffé kinetic measurement in the first series, with an exponential trend. Interference was greater with calcium lactate and glucose: 0.50 +/- 0.16 mg/dL with the same trend. Data from the second series confirm the overestimation: 0.54 +/- 0.05 mg/dL (32.6%) with an exponential trend. The interference of glucose, creatinine, and calcium lactate on the Jaffé kinetic measurement was obtained by multi-variate regression. The single effects of glucose2 and glucose are predominant, but both creatinine and calcium lactate have a significant effect. Our study highlights the nonlinear glucose interference on creatinine measurement with the Jaffé kinetic method and the linear interference of both calcium lactate and creatinine.

The role of hypertension as a damaging factor for kidney grafts under cyclosporine therapy.

The relative importance of glomerular filtration rate (GFR) and hypertension (permanent need for antihypertensive drugs) for the prognosis of kidney grafts was studied in 135 cyclosporine-treated primary cadaver kidney transplant recipients whose grafts lasted more than 1 year. The start point of 1 year after transplantation was chosen because hypertension developed within the first year in all our hypertensive patients. Graft prognosis in hypertensive patients was not significantly worse than that of normotensive patients; moreover at multivariate analysis, age at transplantation and GFR at 1 year (P = 0.014), but not hypertension, were significant prognostic factors for the graft. At logistic regression, GFR was a significant variable for hypertension (P = 0.009), but hypertension was not a significant variable for renal failure at 1 year (GFR < or = 0.83 mL/sec [50 mL n]; P, NS). Accordingly, hypertension per se resulted much more as a consequence of reduced renal function than as a direct cause of graft damage. However, when hypertensive patients were divided into controlled and uncontrolled, uncontrolled hypertensive patients had the worst prognosis (P = 0.03), and blood pressure control proved a strong prognostic factor for the graft, even after GFR was considered (P = value of the model considering blood pressure control, GFR, and age at transplantation: 0.007). Our data suggest that, apart from being an expression of reduced renal function, hypertension is also a direct kidney graft damaging agent, a role that can be controlled by strict reduction of blood pressure levels.

[Mass transfer of magnesium in hemodialysis]. / Mass-transfer del magnesio in emodialisi.

The rate of mass-transfer (MT) of magnesium during hemodialysis was studied in thirty-five patients with hypermagnesemia (Mg = 3.75 +/- 0.72 mg/dl) undergoing chronic hemodialysis. The aim of the study was to verify which is the best dialytical approach to remove the excess of magnesium. The concentration of Mg in the dialysate was of 1.82 mg/dl for all patients. MT was -0.51 +/- 0.36 g and no statistical difference was found between patients treated with cuprophan hollow fibers dialyzers, PAN and cuprophan plates. Mg MT is not correlated with dialysis duration (r = -0.23; p:ns), urea clearance (r = -0.08; p:ns), KT/V index (r = -0.03; p:ns), blood flow (r = -0.15; p:ns). In conclusion from our data, in agreement with other Authors, reduction of serum Mg levels is more convenient by obtained by a decrease in Mg concentration in the dialysate under 1.82 mg/dl, in order to increase the blood-dialysate concentration gradient.

Comparison between three mathematical models of KT/V.

In thirty anuric patients undergoing chronic hemodialysis the KT/V values obtained with the formula: (formula; see text) were compared with the values obtained with the following two formulae: (formula; see text) The results given by formulae B and C differed from those with formula A respectively by 12.81 +/- 11.98% and 10.38 +/- 3.64%. For routine determination of KT/V we suggest the use of formulae A and C as a means of establishing rapidly, in one step, whether the hemodialytic treatment examined is adequate.