SAT-414 When Hypothyroidism Turns Surgical: A Rare Case Of Myxedema Coma Complicated By Acute Compartment Syndrome And Rhabdomyolysis

Abstract Disclosure: S. Obialo: None. B. Moazzami: None. B. Hayes: None. Background: Myxedema coma is a rare, life-threatening complication of severe, untreated hypothyroidism characterized by altered mental status, hypothermia, and multi-organ dysfunction. While it’s known to lead to metabolic derangements, its association with acute compartment syndrome and rhabdomyolysis is exceedingly uncommon and rarely reported. We present a unique case of myxedema coma complicated by bilateral upper and lower extremity acute compartment syndrome and severe rhabdomyolysis. Clinical Case: A 46-year-old male presented with lethargy, bilateral upper and lower extremity swelling and slurred speech. Due to loss of insurance from lack of employment, he was unable to continue taking his medications for the past three to four months. On examination he was somnolent, mild slurring of speech, generalized edema in bilateral upper and lower extremities. Laboratory workup revealed profound hypothyroidism with a TSH of 342 uIU/ml (0.35 – 4.94 uIU/ml) and T4 of < 0.42 ng/dL (0.70 – 1.48 ng/dL). Creatine kinase (CK) was initially elevated at 25,095 IU/L (30 – 200 IU/L), then peaked at 74,000 IU/L (30 – 200 IU/L). Transaminitis was also present with initial AST 179 IU/L (5 – 34 IU/L) and ALT 53 IU/L (less than 55 IU/L) with a peak at AST 1201 IU/L (5 – 34 IU/L) and ALT 208 IU/L (less than 55 IU/L). The patient was started on liothyronine 5 mcg IV and a loading dose of levothyroxine 200 mcg IV followed by 50 mcg oral daily. Stress-dose hydrocortisone100 mg IV every 8 hours was initiated for suspicion of adrenal insufficiency and started on IV maintenance fluids for rhabdomyolysis. Due to increasing CK levels despite IV fluids, he was then upgraded to the ICU for continuous renal replacement therapy to enhance myoglobin clearance and to prevent rhabdomyolysis induced acute kidney injury. Within a few days into the admission, he underwent bilateral upper and lower extremity fasciotomies with later staged wound closure. His thyroid function improved with repeat TSH of 110 uIU/ml (0.35 – 4.94 uIU/ml). CK decreased to 2934 IU/L (30 – 200 IU/L). Glucocorticoids were tapered off near discharge. Conclusion: Early recognition of acute complications of myxedema coma, is paramount to getting the prompt treatment necessary. Clinicians should maintain a high index of suspicion for rhabdomyolysis and evolving compartment syndrome in patients with severe hypothyroidism presenting with extremity swelling and weakness, as early intervention is critical to prevent irreversible tissue damage and multiorgan failure. Presentation: Saturday, July 12, 2025