THU658 My Giant Calves Gave Up My Diagnosis: An Extreme Manifestation Of A Very Rare Syndrome With A Severe Elevation Of Tsh Levels

Disclosure: E.E. Castro Feliu: None. A. Ludena De Freitas: None. A. Torres Rodríguez: None. G. Irizarry: None. Hoffmann’s Syndrome is a rare type of hypothyroidism myopathy in adults that classically presents with muscle cramps, weakness, muscle stiffness, hyporeflexia, delay deep tendon reflexes and pseudohypertrophy. This is the case of a 55-year-old male with history of poorly controlled hypothyroidism and medication non-compliance who was admitted to our institution for non-purulent cellulitis. Vital signs were within normal limits and Body Mass Index was 41.1. Upon physical examination flat affect, periorbital edema, moon facies features and macroglossia were distinguished. Skin had a doughy texture with areas of ichthyosis at upper and lower extremities. Goiter was absent. The most remarkable finding was bilateral calf hypertrophy, with measurements of 56 cm and 55.5 cm in diameter of right and left calves respectively. There was no tenderness to calf palpation and Homan’s sign was absent. Laboratories revealed dyslipidemia with a cholesterol of 308 mg/dL, triglycerides of 782 mg/dL, HDL of 26 mg/dL and LDL of 216 mg/dL with elevated inflammatory markers including sedimentation rate of 77 mm/hr and C-reactive protein of 6.45 mg/dL. Hypothyroidism was suspected therefore thyroid studies were ordered, which was compatible with severe hypothyroidism demonstrated by a record level TSH of 523 lU/ml. Other reported levels were Free T3 0.94pg/ml, total T3 0.5 ng/ml, free thyroxine <0.07 ng/dL, thyroid peroxidase <4, and thyroglobulin AB 19 IU/ml. Hoffmann’s Panel was confirmatory for this diagnosis reporting elevated levels of CPK 1509 U/L, LDH serum of 383 U/L and aldolase of 9.2 u/L. Ultrasound of the neck was non-contributory. Patient received antibiotic therapy for his skin infection and was also treated with IV Levothyroxine, which was prescribed orally upon discharge. Myopathy may be present in patients with longstanding untreated hypothyroidism in which pseudohypertrophy may occur, sometimes involving calf muscles (gastrocnemius). Hoffmann’s Syndrome is associated with changes in muscle fiber type from fast twitch type II to slow twitch type I and alteration of oxidative muscle enzyme activity with deceased calcium ATPase activity of fast twitch type II fibers leading to delayed relaxation. Biopsy of the affected muscle may reveal fiber necrosis, atrophy, hypertrophy with increased number of nuclei and increased connective tissue. Most cases of Hoffmann’s Syndrome improve after treatment with Levothyroxine, therefore, implementing this management on time can be curative. This case highlights the importance of considering this diagnosis when muscle dystrophies are studied and myopathic disorders are suspected, even in the absence of overt manifestations of hypothyroidism. Presentation: Thursday, June 15, 2023