Hypokalemic periodic paralysis associated with thyrotoxicosis, renal tubular acidosis and nephrogenic diabetes insipidus.

A 19-year-old girl presented at our emergency room with hypokalemic periodic paralysis. She had a thyrotoxic goiter and had experienced three paralytic attacks during the previous 2 years on occasions when she stopped taking antithyroid drugs. In addition to thyrotoxic periodic paralysis (TPP), she had metabolic acidosis, urinary potassium loss, polyuria and polydipsia. Her reduced ability to acidify urine during spontaneous metabolic acidosis was confirmed by detection of coexisting distal renal tubular acidosis (RTA). The polyuria and polydipsia were caused by nephrogenic diabetes insipidus, which was diagnosed using the water deprivation test and vasopressin administration. Her recurrent and frequent paralytic attacks may have been the combined effects of thyrotoxicosis and RTA. Although the paralytic attack did not recur after improving the thyroid function, mild acidosis and nephrogenic DI have been remained subsequently. Patients with TPP, especially females with atypical metabolic features, should be investigated for possible precipitating factors.