Potassium depletion in surgical patients: Intracellular cation deficiency is independent of loss of body protein

Abstract

Neutron activation analysis and skinfold measurement were used to measure body composition of 12 surgical patients before and after a 2 week course of intravenous nutrition with glucose as the source of energy. Pre-illness body composition was predicted using regression equations which considered age, sex and height. At the onset of intravenous nutrition, mean total body potassium was 1857 mmol or 30% less than predicted. Other components of body cell mass which included body nitrogen, were reduced by 15–20%. Although 60% of the deficit of potassium could be explained by depletion of body protein and glycogen, 40% probably reflected a subnormal intracellular potassium concentration. Intravenous nutrition with dextrose and amino acids resulted in a gain of body potassium of 210 ± 44 mmol (p < 0.001) in the group of patients. Potassium and nitrogen were repleted in a rate of 1.69:1 (mmol:g) suggesting that the majority of potassium repletion was independent of muscle synthesis. Thus changes of body potassium during starvation and refeeding do not reflect protein synthesis and are not equivalent to changes in body nitrogen.