Hypokalaemia and paralysis

It is not uncommon for patients to present to the emergency room with severe weakness and a markedly low plasma potassium concentration. We attempted to identify useful clues to the diagnosis of hypokalaemic periodic paralysis (HPP), because its acute treatment aims are unique. We retrospectively reviewed charts over a 10-year period: HPP was the initial diagnosis in 97 patients. Mean patient age was 29 ± 1.1 and the male:female ratio was 77:20. When the final diagnosis was HPP (n=73), the acid-base state was normal, the urine K⁺ concentration was low, and the transtubular K⁺ concentration gradient (TTKG) was + excretion in the presence of hypokalaemia, and a TTKG of close to 7. With respect to therapy, much less K⁺ was given to patients with HPP, yet 1:3 subsequently had a plasma K⁺ concentration that eventually exceeded 5.0 mmol/l. Using plasma acid-base status, phosphate and K⁺ excretion parameters allows a presumptive diagnosis of HPP with more confidence in the emergency room.