Three cases of thyrotoxic periodic paralysis due to painless thyroiditis
A 32-year-old male presented with acute onset flaccid paraparesis, tremors of both hands and palpitations. He had a history of transient proximal weakness 6 weeks back which recovered spontaneously. He had no dysphagia dysphonia, bladder, or bowel involvement.\nHe had power 2/5 in proximal muscles, depressed jerks on all four limbs, bilateral flexor plantar responses, and no signs of cranial nerve palsy. He had tachycardia, fine tremors of both hands, and grade1 diffuse goiter. His serum potassium was 1.8 mmol/l, ESR 30 mm/h, TSH 0.03 μU/l, free T4:3.2 ng/dl, TPO antibody 117 IU/ml (nl < 35), and there was decreased uptake (0.21%) on 99mTc scan.\nAll three cases had normal TSH receptor antibodies, serum creatine kinase (CK) and collagen vascular profile. Blood gas analysis in all three patients excluded acidosis. NCV was normal but EMG showed a myopathic pattern with no decremental muscle action potential. In all three cases fine-needle aspiration cytology (FNAC) was consistent with lymphocytic thyroiditis. Based on clinical features and investigations our diagnosis for each patient was thyrotoxic periodic paralysis secondary to painless or silent thyroiditis.\nCase 1 was managed with oral potassium chloride (KCl) at the rate of 0.2-0.4 mmol/kg and propanolol 120 mg/day. Cases 2 and 3 initially required intravenous KCl at 10 meq/h. All showed marked improvement of paralysis within a week of treatment. All patients were discharged after a week with oral propranolol (80-120 mg/day). After 4 weeks of mean follow-up none had any residual paralysis. At the end of 2 months case 1 presented with normal thyroid profile and propranolol was completely withdrawn. At 3 months the thyroid profile became completely normal in cases 2 and 3 and propanolol was stopped. There was no relapse in any of the three cases even at 6-month follow-up.