Exploring the enigma of thyrotoxic periodic paralysis: A complex interplay of hormones and muscles

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ABSTRACT Background: Thyrotoxic periodic paralysis is an uncommon presentation of thyrotoxicosis , predominantly affecting the young Asian males (Incidence 1.8-2%). Classically seen with Grave`s disease. Aims and Objectives: To the study the etiology of thyrotoxic periodic paralysis. To study the clinical profile, precipitating causes and response to treatment of thyrotoxic periodic paralysis. Materials and Methods: All patients diagnosed to have thyrotoxic paralysis in the departments of Medicine, neurology and endocrinology in Pushpagiri Institute of medical science and research centre , Thiruvalla were included in the study. A total of 20 patients were included in the study. The Thyroid functions, CPK, Na+, K +, Ca++ , Phosphate and Magnesium were estimated for all patients. All patients underwent a thyroid ultrasound and Technetium uptake scan, to find the etiology of thyrotoxicosis. Waynes Index was calculated to look at severity of thyrotoxicosis. Results: Out of the 20 patients, 14 patients had Graves disease, 4 had toxic MNG, and 2 had thyroiditis. All patients were male, and 7 patients were manual labourers. Bowel, bladder pharyngeal muscles, respiratory muscles and sensory were not involved in any patient. Only 6 patients had Waynes Index more than 19.In majority of patients paralysis was precipitated by carbohydrate .Recurrent episodes of paralysis was seen in 7 patients, and 13 had a single episode. The mean free T4 was 3.43 ng/ml with range from 2.84 - 4.02. The serum K+ levels ranged from 1.73 meq/L to 3.45 meq/L (mean 2.59). The CPK levels were elevated in eight patients,all with Grave’s disease. The paralysis resolved in all patients after K+ correction and Propranolol .Four patients had rebound hyperkalemia. Conclusions: Graves disease still remains the commonest cause of thyrotoxic paralysis, but can occur with Toxic MNG and thyroiditis. The weakness does not correlate with the severity of toxicosis or Potassium values.The paralysis responds to Potassium correction, but can result in rebound hyperkalemia.