Thyrotoxic hypokalaemic periodic paralysis (THPP) is an uncommon potentially life-threatening endocrine emergency characterized by sudden onset of muscle weakness with hypokalaemia that resolves with treatment of hyperthyroidism. Reported predominantly among individuals of Asian descent, THPP is rare in western populations. We present 2 cases of THPP diagnosed within 6 months in a district general hospital.
First patient: a 37 year white male presented with sudden weakness of his limbs. He had played golf the day before. There was marked muscle weakness more prominent proximally in his legs. He was tachycardiac with hypokalaemia (2.5 mmol/l). Systematic enquiry elicited a 6-month history of hyperthyroid symptoms. He had a small diffuse goitre and mild left eye proptosis. Free T3: >30 pmol/l. Symptoms totally resolved with potassium supplements and carbimazole followed by radioactive iodine.
Second patient: an 88 year white female presented with a few months history of tiredness, anorexia, dysphagia, weight loss and recurrent episodes of limb weakness and falls. She had hypokalaemia (2.7 mmol/l) and anaemia. In view of the anaemia and dysphagia she underwent gastroscopy, which made comment about some distortion of the oropharyngeal anatomy. CT scan of her neck showed a goitre causing some displacement of the pharynx. Free T3: 8.8 pmol/l. Symptoms improved with potassium replacement and carbimazole, with no further falls. Although the first case had classical symptoms of hyperthyroidism for six months it was the sudden onset of muscle weakness, due to hypokalaemia, that led to his presentation. In the second case the finding of goitre at gastroscopy led to the diagnosis of hyperthyroidism. While hyperthyroidism can be associated with myopathy, THPP should be considered in patients with acute episodic paralysis, including elderly patients with falls. Early diagnosis and prompt treatment prevent life-threatening complications of this curable disorder and maintenance of euthyroid status prevents the paralytic episodes.
06 - 07 Nov 2006
Society for Endocrinology