Thyrotoxic hypokalaemic periodic paralysis in a Turkish population: three new case reports and analysis of the case series

Abstract

Objective: Thyrotoxic hypokalaemic periodic paralysis (THPP) is an uncommon condition with intermittent episodes of muscle weakness and occasionally severe paralysis. THPP is a common complication of hyperthyroidism in Asian populations, and has also been reported in other ethnic groups including Caucasians. This study aimed to conduct an analysis of THPP in a Turkish population, and is to our knowledge the first analysis of a homogeneous Caucasian group.

Subjects: Forty cases with THPP were identified in the Turkish population. Three out of the 40 were new cases and were assigned as index cases. Two cases were not included in the analysis because of lack of data.

Results: THPP was diagnosed in 10 cases during the first attack and was observed to have a significant shorter complete recovery time statistically in this group (P < 0.01). The majority of cases were hypokalaemic, while there were two normokalaemic cases. Classification of the cases according to their potassium (K) levels revealed that the group with K levels < 2.5 mEq/l had a statistically longer amelioration time than the group with K levels > or = 2.5 mEq/l. When the cases were classified according to intravenous or oral application of K, the mean amelioration time was 6.8 +/- 3.6 h for the intravenous group and 13.1 +/- 7.6 for the oral group. Mean complete recovery times of the groups were 29.4 +/- 16.2 h and 52.8 +/- 18.0 h, respectively. The intravenous group had a shorter amelioration time and complete recovery time, and both were statistically significant (P < 0.05 for each).

Conclusions: THPP may be seen among Caucasians. Diagnosing THPP during the first attack might decrease the recovery time. The level of hypokalaemia seems to affect the recovery time and initial low K levels may lead to more deterioration in a patient's health compared with mild or near-normal levels. Intravenous, rather than oral, application of K may be advantageous for shortening both the amelioration and complete recovery times.