Total body potassium, fat and water during total parenteral nutrition in Crohn's disease

The body composition was studied by measurement of body weight (BW) and total body potassium (TBK), fat and water in 13 patients with Crohn's disease (CD), who were given altogether 18 courses of total parenteral nutrition (TPN) with nil by mouth each lasting at least 3 weeks. At the start of TPN, one group of steroid-free patients displayed intracellular potassium depletion, as reflected by the ratio TBK/lean body mass (LBM) (group 1). Another group of steroid-free patients showed no depletion of intracellular potassium (group 2). The patients given prednisolone all showed intracellular potassium depletion and were assigned to a separate group (group 3). During the initial 19-44 days of TPN, TBK, LBM and BW increased in group 1. All patients with intracellular potassium depletion (groups 1 + 3) showed an increase in TBK and TBK/LBM during the initial 19-51 days of TPN. For steroid-free patients (groups 1 + 2) there were linear relationships between the rate of energy supply per kg LBM and the 24 h change in BW during the third and fourth weeks of TPN (r = 0.79) and between the 24 h change inBW and LBM during the first 19-44 days of TPN (r = 0.59). A steady state in BW was found on administering 53 kcal/kg LBM/24 h. It is concluded that CD patients with intracellular potassium depletion are likely to be improved in terms of TBK and TBK/LBM by at least 3 weeks of TPN as given in the present study. Steroid-free CD patients with intracellular potassium depletion are, moreover, likely to show an improvement in LBM by at least 3 weeks of TPN, and an increase in their BW during the initial 3-6 weeks of TPN will probably reflect an increase in LBM. The pre-TPN TBK/LBM ratio may be a predictor of the repletion rate of the LBM compartment during TPN of steroid-free wasted CD patients.