Thyrotoxicosis and renal tubular acidosis presenting as hypokalaemic paralysis

A 34-yr-old Chinese woman presented with hypokalaemic periodic paralysis. She had a goitre and was biochemically thyrotoxic. However, she also had urinary potassium loss with a metabolic acidosis and reduced ability to acidify her urine. The co-existence of distal renal tubular acidosis (RTA) was confirmed. There was no evidence of xerostomia or xerophthalmia, although anti-Ro antibody and rheumatoid factor were positive. Paralytic attacks did not recur after the thyrotoxicosis was controlled with radioactive iodine. Possible pathogenic mechanisms for the association of these disorders are discussed. Female patients presenting with thyrotoxic periodic paralysis (TPP) should be thoroughly investigated for possible additional precipitating factors in view of the strong male predominance of TPP, particularly when there are atypical metabolic features.