[Measurement of total body water with deuterium oxide in renal diseases]

Total body water was measured by means of dilution technic with 99.8% deuterium oxide administration in normal subjects (controls), nephrotic (NS) patients with or without edema, and in longterm hemodialysis (HD) patients. Lean body mass (LBM) was calculated from height, body weight, and waist girth. Body fluid was evaluated according to the TBW/LBM ratio in HD patients. Effect of volume of body fluid on blood pressure was also investigated. Relationship among cardio-thoracic ratio (CTR), standard body weight (SW), and TBW were examined. SWTBW calculated from TBW and LBM, and SWCTR estimated mainly from CTR, blood pressure, were compared. The total body water to body weight ratios (TBW/BW) in controls, NS, and HD patients were 61.2 +/- 1.2%, 71.3 +/- 3.7% (with edema), 60.9 +/- 6.4% (without edema), 64.5 +/- 6.9% (pre-HD), 62.6 +/- 6.6% (post-HD) respectively. The mean TBW/BW of NS patients with edema was significantly greater than those of control, NS patients without edema, and post-HD patients. The TBM/LBM value above 0.78 was suggestive of overhydrated state in HD patients. The mean TBW/LBM in HD patients was 0.757, which was greater than that of controls. Hypotension during HD was seemingly induced by excess ultrafiltration regardless of the value of TBW/LBM. No relationship among CTR, SW, and TBW was observed in HD patients, but the mean TBW/LBM of patients with the CTR exceeding 55% was 0.786, which suggested as overhydrated state. It is useful to determine TBW/BW and TBW/LBM in order to evaluate of volume changes in body fluid of longterm HD patients.