In attempting to identify variables that might account for the frequent absence of edema in HIV-infected patients with end-stage renal disease, we evaluated 24 consecutive patients at our institution who had HIV infection and developed end-stage renal disease. Clinical and laboratory data prior to the initiation of hemodialysis were recorded and compared between patients with and without edema. Only 11 of the 24 study patients had edema while the remainder did not. The prevalence of diarrhea was significantly less in patients with edema (one of 11 patients compared to eight of 13 with no edema, p < 0.02, odds ratio 0.063). Prior weight loss was significantly less in the patients with edema (9.1 +/- 1.3 kg vs 15.5 +/- 2.2 kg, p < 0.05). Use of antiretroviral therapy was significantly greater in patients with edema (p < 0.05, odds ratio 10.1). None of the patients were receiving diuretics. Blood pressure was significantly higher (p < 0.001) in patients with edema, and serum albumin was low in both groups but did not differ (edema, 24 +/- 2 g/L; no edema, 21 +/- 3 g/L). Four patients had albumin levels as low as 2, 8, 9, and 10 g/L, yet they had no edema. CD4 counts were lower in patients without edema (62 +/- 16 x 10(6) cells/L vs 283 +/- 38 x 10(6) cells/L, p < 0.001). Absence of diarrhea was predictive of the presence of edema with a sensitivity of 91% and specificity of 62% while mean arterial blood pressure > 95 mm Hg was predictive of the presence of edema with a sensitivity of 82% and specificity of 77%. CD4 of > 100 x 10(6) cells/L was predictive of the presence of edema with a sensitivity of 91% and specificity of 77%. These data support the hypothesis that hemodynamic factors may play a role in the frequent absence of edema in patients with HIV infection and renal failure, and variables including diarrhea, low blood pressure, weight loss, and more advanced stage of HIV infection may account for this observation. Hence, the absence of edema should not dissuade the clinician from considering the possibility of advanced renal failure in HIV-infected patients.