Uraemic symptoms, nutritional status and renal function in pre-dialysis end-stage renal failure patients

Background. Deciding on the right moment to initiate dialysis and finding the best method to establish this critical stage of chronic renal failure are both controversial issues. This study attempted to address this subject by correlating a uraemic score with the most common clinical methods for assessing renal function in pre-dialysis chronic renal failure (end-stage renal disease, ESRD) patients. Methods. The study group consisted of 201 nonselected ESRD patients. A uraemic score, composed of the uraemic symptoms, the subjective global assessment of nutritional status, serum albumin concentration, and protein catabolic rate normalized for ideal body weight, was taken as a clinical marker of uraemic toxicity. Correlations that best fit this uraemic score with creatinine clearance (Ccr), the arithmetic mean of Ccr, urea clearance (Ccr-Cu) and Kt/V urea were then investigated. Results. Thirty-six per cent of patients had malnutrition. By multiple logistic regression analysis, the presence of comorbidity, Ccr-Cu and haematocrit were the best determinants of malnutrition. The correlation that best fit Ccr or Ccr-Cu with the uraemic score was a cubic curve (r = 0.38, P < 0.0001, and r = 0.42, P < 0.0001, respectively), in which an ascending inflection was observed when Ccr and Ccr-Cu fell below 12-13 and 10 ml/min, respectively. However, the relationship between Kt/V urea and the uraemic score was less predictable, especially in male patients. Conclusion. Ccr or Ccr-Cu are reliable methods for establishing the degree of severity of chronic renal failure below which the development of symptoms and malnutrition are highly prevalent. In contrast, Kt/V urea may be a less sensitive and specific method for assessing the severity of uraemia in ESRD patients.