ODP513 Rhabdomyolysis: A Rare Presentation Of Central hypothyroidism

BACKGROUND: Hypothyroidism is one of the most common endocrine disorders affecting approximately 5 percent of Americans aged 12 and older. The most common cause of hypothyroidism globally is iodine deficiency whereas in the United States, Hashimoto's thyroiditis is the most prevalent. Less frequently, hypothyroidism can be caused by central hypothyroidism. In uncontrolled states, this entity can lead to an array of complications with rhabdomyolysis being among the latest manifestations. We present a case when the patient was admitted to the hospital for significant rhabdomyolysis, and after workup, was found to be related to new onset central hypothyroidism. CLINICAL CASE: A 34-year-old African American male presented to our facility with proximal muscle weakness and pain in the bilateral hips and right shoulder for three days. During the interview, the patient was acutely debilitated demonstrating slow body movements and grimaces on passive and active range of motion. Motor strength and sensation was preserved in bilateral extremities. The patient denied any recent injury, compression, extensive exercise, seizure, or durg use. The patient, however, reported a family history of rheumatological and endocrine conditions. Labs were obtained and revealed a creatinine kinase level of 10,5000 U/L; creatinine kinase- MB 53.5 ng/mL; creatinine 1. 0 mg/dL; AST 146 U/L; ALT 72 U/L; CRP 8.6 mg/L. The patient was stabilized with appropriate fluid and steroid therapy. On further investigation, TSH and T4 levels were 0.30 µlU/mL and 0.55 ng/dL, respectively. MRI with and without contrast did not show any intracranial pituitary abnormality or mass. The patient was started on levothyroxine and instructed to remain on the drug as an outpatient to prevent future occurrences. He was subsequently discharged after CK levels normalized and proximal muscle weakness improved. The patient was instructed to have a repeat thyroid function test and T4 levels in 6 weeks with appropriate follow up. CONCLUSION: Idiopathic central hypothyroidism is a rare cause of hypothyroidism estimated to occur in 1: 20,000-80,000 in the general public. The lack of a pituitary mass lesion on MRI added to the rarity of this presentation. Hypothyroid myopathy causing rhabdomyolysis is a known but rare consequence of untreated hypothyroidism, which may present with muscle weakness, pain, and elevated serum muscle enzyme. Prompt workup to rule out a multitude of other causes is required, and the patient should be closely monitored for electrolyte and kidney function changes. Levothyroxine remains the treatment of choice for correction of central hypothyroidism with dose adjustments based on patient symptoms and serum free T4 values. Presentation: No date and time listed