Thyrotoxic periodic paralysis in a Chinese population

Area of Science:

• Endocrinology
• Neurology
• Metabolic Disorders

Background:

• Thyrotoxic hypokalaemic periodic paralysis (THPP) is a rare condition characterized by episodes of muscle weakness due to low serum potassium levels in individuals with hyperthyroidism.
• It predominantly affects Asian males and can present with varying degrees of thyrotoxicosis, sometimes without overt clinical signs.

Purpose of the Study:

• To retrospectively evaluate the clinical characteristics of adult patients admitted with THPP in Hong Kong.
• To identify demographic, clinical, and biochemical features associated with THPP in this population.

Main Methods:

• Retrospective analysis of adult patients admitted between 1984 and 1993 with confirmed thyrotoxicosis and hypokalemia (plasma potassium ≤ 3.5 mmol/l).
• Data collected included patient demographics, timing and frequency of attacks, plasma potassium levels on admission and recovery, family history, and history/clinical evidence of thyrotoxicosis.

Main Results:

• 45 Chinese adult patients (44 males) were identified. Attacks predominantly occurred nocturnally and during summer months (July-October).
• Mean admission plasma potassium was 2.17 ± 0.08 mmol/l. Rebound hyperkalemia (>5.0 mmol/l) occurred in 27.3% of episodes.
• Only 28.9% had a prior diagnosis of thyrotoxicosis, and 11.4% had only mild biochemical thyrotoxicosis, highlighting diagnostic challenges.

Conclusions:

• THPP should be strongly considered in Chinese patients presenting with acute muscle weakness, particularly young males, even without clear clinical signs of thyrotoxicosis.
• Close monitoring of plasma potassium during treatment is essential to manage hypokalemia and prevent potentially dangerous rebound hyperkalemia.