Potassium substitution via the oral route: does its efficacy depend on the anion of the potassium salt?

In an open, randomized study, we investigated the effect of oral potassium chloride (KCl) and of potassium citrate/bicarbonate (K-cit/bic) in 42 patients with hypokalemia (less than or equal to 3.5 mmol/l). In both groups 80 mmol K+ were administered daily. The parameters examined were serum potassium concentration, acid-base status, and urinary electrolyte excretion. Parameters were evaluated on days 0, 2, 4, and 6. With KCl, [K+] increased from 3.2 +/- 0.2 (mean +/- SD) on day 0 to 3.8 +/- 0.4 mmol/l on day 2 (p less than 0.005) and 4.0 +/- 0.5 mmol/l on day 4 (p less than 0.005). On day 6 [K+] was also 4.0 +/- 0.4 mmol/l (p less than 0.005 vs day 0). With K-cit/bic, [K+] increased from 3.2 +/- 0.2 to 3.7 +/- 0.4 on day 2, 3.9 +/- 0.5 on day 4, and 4.1 +/- 0.6 mmol/l on day 6 (all p less than 0.005 vs day 0). The increase of [K+] was not different between the two groups. Blood pH on day 0 was in the normal range in both groups and did not change significantly during the study. There was a decrease of carbon dioxide partial pressure (pCO2) with KCl from 38.7 +/- 4.9 on day 0 to 36.4 +/- 3.6 on day 2 (p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)