Endocrine Abstracts

Introduction: Thyrotoxic periodic paralysis (TPP) is a complication of hyperthyroidism characterized by muscle paralysis and hypokalemia. It mainly affects male patients of Asian descent. Many patients do not have obvious symptoms and signs of hyperthyroidism, which makes its diagnosis difficult.

Case report: A 47-year-old Asian man presented with all four limbs rapidly progressive muscular weakness that caused him inability to walk. He referred a previous episode with spontaneous recovery. Guillain–Barre syndrome and spinal cord disorders had been ruled out. He denied fever and any medication in previous days. The physical examination revealed lower limbs proximal weakness (strength 3/5) and areflexia. Blood tests showed hypokalemia, hypophosphatemia, hypomagnesemia, elevated creatine kinase level with normal acid-base balance, decreased TSH level (0.01 μUI/l) and elevated free T4 (2.41 ng/dl). The patient was positive to antimicrosomal and anti TSH-receptor antibodies and negative to antithyroglobulin antibodies. Ultrasonography revealed a heterogeneous and hypervascular thyroid with goitre. The patient was diagnosed with TPP and treated with intravenous potassium supplementation. Full recovery was achieved in less than 24 h. Further treatment with beta blockers and antithyroid drugs was prescribed. Definitive treatment for Graves-Basedow disease with Iodine-131 was scheduled.

Conclusions: TPP is a well-known complication in Asian populations. It is becoming increasingly common in other areas like Europe due to population mobility. The majority of cases are due to Graves’ disease although the 90% of patients have clinically silent hyperthyroidism at the time of TPP diagnosis. Thus, thyroid function should be evaluated in patients presenting with muscle weakness and hypokalemia to distinguish it from other forms of hypokalemic periodic paralysis. It is recommended to test thyroid hormones in Asian descent patients presenting with muscle weakness.