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

Summary

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 (≤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<0.005) and 4.0± 0.5 mmol/l on day 4 (p< 0.005). On day 6 [K⁺] was also 4.0±0.4 mmol/l (p< 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 (allp< 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<0.05). On days 4 and 6, pCO₂ was back up to the basal level. In contrast, with K-cit/bic, pCO₂ rose from 35.0±5.8 mmHg on day 0 to 39.9± 5.8 mmHg on day 2 (p< 0.05). On days 4 and 6, pCO₂ was not different from day 0. The increase in urinary potassium excretion was equal in both groups. These results indicate that oral substitution with either KCl or K-citrate/bicarbonate may have only minor effects on the acid-base status under the conditions of the present study. Both potassium salts appeared to be equally effective in correcting hypokalemia via the oral route.