BACKGROUND: Thyrotoxic periodic paralysis (TPP) is commonly observed in patients with acute paralysis and hyperthyroidism. However, there is a possibility of secondary causes of hypokalemia in such a setting.

CASE REPORT: Herein, we present the case of a 38-year-old woman with untreated hypertension and hyperthyroidism. She presented with muscle weakness, nausea, vomiting, and diarrhea since one week. The initial diagnosis was TPP. However, biochemistry tests showed hypokalemia with metabolic alkalosis and renal potassium wasting. Moreover, a suppressed plasma renin level and a high plasma aldosterone level were noted, which was suggestive of primary aldosteronism. Abdominal computed tomography confirmed this diagnosis.

CONCLUSIONS: Therefore, it is imperative to consider other causes of hypokalemia (apart from TPP) in a patient with hyperthyroidism but with renal potassium wasting and metabolic alkalosis. This can help avoid delay in diagnosis of the underlying disease.

Keywords: Hyperaldosteronism, Hypokalemia, Hypokalemic Periodic Paralysis, Thyrotoxicosis