Rhabdomyolysis associated with hyperthyroidism

Area of Science:

• Endocrinology
• Neurology
• Internal Medicine

Background:

• Nontraumatic rhabdomyolysis is linked to various conditions including substance abuse, seizures, and metabolic disorders.
• Hyperthyroidism commonly presents with neuromuscular issues like thyrotoxic myopathy, typically with normal creatine phosphokinase.
• Rhabdomyolysis secondary to thyrotoxicosis is exceedingly rare, with only three prior cases reported.

Observation:

• A 26-year-old woman with hypertension presented with symptoms of hyperthyroidism, including blurred vision, palpitations, and weight loss.
• Physical examination revealed exophthalmos and goiter; Graves disease was diagnosed based on positive TPO antibodies and abnormal thyroid function tests.
• Following diagnosis and treatment with propylthiouracil, the patient developed weakness and myalgias, with elevated creatine phosphokinase levels.

Findings:

• The patient's laboratory results showed elevated free T4 and T3 with suppressed TSH, alongside significantly elevated creatine phosphokinase (1276 U/L).
• Despite normal electrolytes and renal function, the clinical presentation and labs indicated rhabdomyolysis.
• Treatment with continued propylthiouracil and aggressive fluid resuscitation led to normalization of thyroid hormones and creatine phosphokinase, resolving symptoms.

Implications:

• This case reinforces that hyperthyroidism can precipitate rhabdomyolysis, possibly due to increased muscle energy demands and substrate depletion.
• It underscores the importance of considering thyrotoxicosis in the differential diagnosis of rhabdomyolysis, even in its absence of typical neuromuscular symptoms.
• This report adds to the scarce literature, emphasizing the need for vigilance regarding this rare but severe complication of hyperthyroidism.