Hypertension profiling by total body water (TBW) determinations in patients on chronic hemodialysis

Hypertension is an important risk factor in hemodialysis patients. Fluid overload and increased peripheral resistance are considered the two main causes. We studied the relation between volume state and blood pressure in 18 hemodialysis patients. Actual total body water (aTBW) was measured as tritium space and "ideal" total body water (iTBW) by an anthropometric method. The difference between aTBW and iTBW was considered a measure of fluid excess or deficit. Twelve patients were overhydrated, 5%-23%. Their predialysis blood pressure was significantly correlated to their degree of fluid excess; systolic BP:r = 0.71, p = 0.03, diastolic BP:r = 0.73, p = 0.02, mean arterial BP:r = 0.76, p = 0.03. Five of these patients had multiple antihypertensive drugs instead of adequate ultrafiltration. Five patients had a fluid deficit of -3 to -13% and hypertension due to vasoconstriction. Four of these were adequately treated with antihypertensive drugs but had exaggerated ultrafiltration. TBW determination with tritium is simple to perform and gives information on the volume state and thereby on the cause of hypertension in hemodialysis patients. Based on this, appropriate treatment can be chosen.