Therapeutic analysis in Chinese patients with thyrotoxic periodic paralysis over 6 years

Abstract

ObjectiveTo characterize the course of therapy in a large cohort of Chinese patients with thyrotoxic periodic paralysis (TPP), a reversible electrolyte emergency fraught with therapeutic challenges.Design and methodsIn this prospective interventional study, 78 patients with TPP (75 males and three females with an age range of 16–48 years) were consecutively enrolled over a 6-year period. Intravenous KCl at a rate of 10 mmol/h was administered until muscle strength recovered. Serum potassium (K+) and phosphorus concentrations were measured hourly during the paralytic attack and for 6 h after recovery.ResultsThe serum potassium (K+) on attack was 2.1±0.2 mmol/l. The dose of KCl administered to restore muscle strength was 63±32 mmol, and peak serum K+ concentration after recovery was 5.3±0.5 mmol/l. A paradoxical fall in serum K+ concentration >0.1 mmol/l difference between presentation and treatment nadir was observed in approximately one-fourth of TPP patients (n=20). These patients had significantly higher serum-free thyroxine concentration, systolic blood pressure, and heart rate on presentation, as well as serum phosphate concentration on recovery. They not only needed much more KCl supplementation (104±34 vs 48±19 mmol, P<0.001), but also had significantly more severe rebound hyperkalemia (5.8±0.5 vs 5.1±0.4 mmol/l, P<0.001) on recovery than those who did not have paradoxical hypokalemia. There was a positive correlation between the dose of KCl administered and the difference between peak and nadir serum K+ (Δ K+) (r=0.68, P<0.001).ConclusionsTPP patients who do not develop paradoxical hypokalemia need a smaller KCl dose to achieve recovery, whereas those who develop paradoxical hypokalemia have more severe hyperthyroidism and hyperadrenergic activity and may require blockage of intracellular K+ shift to prevent rebound hyperkalemia.