Is weight gain inevitable in most chronic peritoneal dialysis patients?

In order to determine the long-term effects of continuous peritoneal dialysis on weight, 100 consecutive patients entering our program in 1988 were studied and followed for a maximum of 36 months. All patients underwent monthly evaluations including weight and biochemical surveys. Peritoneal equilibration tests were performed in 75 patients. A definite and significant trend was noted for weight gain during the first 17 months with a mean weight gain of 6.41 +/- 8.36 kg or 6.4% increase (p < 0.01). This was followed by a downward trend with a nadir on month 21 (p < 0.05). There were no significant differences in the change in weight for small or large patients. A positive correlation was noted between weight change and D/P creatinine at 12 and 24 months. Albumin concentrations remained stable throughout the period of observation. Serum albumin did not correlate with percent weight change nor with D/P creatinine. The frequency of peritonitis did not influence weight change in this population. The data suggest that there is marked interpatient variation, but the majority of patients on chronic peritoneal dialysis experience significant weight gain upon initiation of therapy. The trend is reversed after approximately 1.5 years of therapy raising the question of underdialysis due to loss of residual renal function or from patient selection after transfer of the healthier patients to transplantation and/or hemodialysis.