Hyperkalemia in patients on enteral feeding

The amount of potassium (K) in proprietary enteral feeds varies considerably from 2.7-9.2 mmol K+/g N. It has been suggested that up to 7 mmol K+/g N is required by the anabolic patient. The aim of this study was to determine the effect of a proprietary feed (Triosorbon MCT), containing 6.9 mmol K+/g N, on serum and urinary K in 13 patients requiring nutritional support. Serum electrolytes in all patients and urinary electrolytes in 7 were measured both before feeding commenced and when they had achieved an intake of between 2.4 and 3.0 liter/day (102-127 mmol K+/day) of full strength feed for a period of 1 wk. Ther serum K rose in all patients from 4.2 +/- 0.5 mmol/liter (mean +/- SD) before feeding to 5.1 +/- 0.5 after feeding for 1 wk (p less than 0.001; pair-difference t-test). The daily urinary K excretion rose from 37.8 +/- 24.2 mmol/day to 61.8 +/- 26.6 over the same period (p less than 0.001) The serum urea rose from 4.7 +/- 2.0 mmol/liter to 6.3 +/- 3.2 (p less than 0.05). No significant change was observed in other serum electrolytes, creatinine, or urinary electrolytes. During the whole course of feeding (range 1-11 wk) it was necessary to discontinue Triosorbon in 2 patients whose serum K concentration became elevated to greater than 6 mmol/liter. We conclude that the recommended levels of K intake may be too high and that serum K should be carefully monitored during enteral feeding.