LDH isoenzyme of the dialysate in noninfected PD patients

We wished to investigate lactic dehydrogenase (LDH) and its isoenzymes in the dialysate of peritoneal dialysis (PD) patients under noninfected conditions. Twenty-seven continuous ambulatory peritoneal dialysis (CAPD) patients (20 males, 7 females; mean age 53 years; average duration of CAPD 29 months) were studied. Overnight dialysate and blood samples were collected. LDH activities, isoenzymes, glucose, creatinine of both specimens, and cancer antigen 125 (CA125) of the dialysate were determined. Serum and dialysate LDH was 470 +/- 163 and 10 +/- 4 U/L, respectively. Percentages of LDH1, LDH2, LDH3, LDH4, and LDH5 were 29 +/- 5, 37 +/- 4, 20 +/- 3, 9 +/- 4, and 6 +/- 2 (%) in the serum, 21 +/- 5, 30 +/- 5, 23 +/- 6, 16 +/- 4, and 8 +/- 3 (%) in the dialysate, respectively. There was no significant relationship between the serum and dialysate LDHs. There were no correlations between dialysate LDH, patient's age, duration of CAPD, peritoneal transport properties, and dialysate CA125. Although it was still difficult to determine the origin of dialysate LDH, a predominance of LDH5 was not observed in noninfected stable patients. Dialysate LDH activities were low, and the isoenzyme patterns were similar to those of the serum. Alteration of the isoenzyme patterns may suggest unfavorable events, such as infection, in the peritoneal cavity.