Thyroid Myopathy With Rhabdomyolysis Presenting as Agitation: A Case Report

Sir: Rhabdomyolysis, a syndrome characterized by muscle necrosis, can be fatal, and it needs immediate attention. It can be classified as either traumatic or non-traumatic.¹ Nontraumatic rhabdomyolysis is associated with many etiologies, including hypothyroidism.² In both traumatic and nontraumatic rhabdomyolysis, intracellular muscle contents are released into systemic circulation. There are a few reported cases of hypothyroidism disclosed by rhabdomyolysis.^2–6 We hereby report a rare case of a patient who presented with new-onset gait abnormalities, limb weakness, rhabdomyolysis, and agitation, which were precipitated by noncompliance with levothyroxine and were secondary to hypothyroidism. The noncompliance was secondary to the patient's paranoia. Since the patient carried the diagnosis of schizophrenia, his agitation was automatically and incorrectly attributed to his mental illness.

Case report

Mr. A, a 65-year-old white man, was admitted to the psychiatric intensive care unit (PICU) for psychomotor agitation and combative behavior in April 2007. He had a past medical history significant for hypothyroidism secondary to thyroidectomy and radical neck dissection for carcinoma. It was reported that, a few weeks before admission, Mr. A had been threatening his caregivers, shaking his fist, and raising his voice. In addition, 2 days prior to admission, he woke up unable to walk but able to crawl to a phone and seek help.

Mr. A's agitation was presumed to be a result of his mental illness. Due to his past psychiatric history of untreated schizophrenia, he was directly admitted to the PICU from the emergency room. The results of a complete blood count, basic metabolic profile, erythrocyte sedimentation rate, coagulation profile, magnesium and phosphate levels, liver function tests, urine drug screen, and routine urine analysis were normal. Mr. A's creatinine kinase (CK) level was elevated at 394 IU/L (normal range, 30–170 IU/L), with a CK-myocardial band isoenzyme fraction of 7.7, and his myoglobin level was elevated at 153 ng/mL. His troponin levels were normal. Thyroid-stimulating hormone (TSH) and thyroxine (T₄) levels were 60.4 mU/L and 2.9 mU/L, respectively. A head computed tomography scan revealed no definitive acute intracranial abnormality but was suggestive of chronic microvascular ischemic gliosis. A neurology consultation was sought for new-onset gait abnormalities and limb weakness. Mr. A refused to follow through with the consultant's recommendations of further neuroimaging, including a magnetic resonance imaging scan. His lower extremity weakness and gait instability were attributed to his profound hypothyroidism. The plan was to initiate levothyroxine along with physical therapy, but the patient did not agree to it.

Mr. A's CK level continued to elevate during his stay and peaked at 4969 IU/L on the fifth day after admission. Due to these high levels, he was transferred to the medical intensive care unit. Mr. A continued to be uncooperative with all of the interventions, including intravenous hydration. He was eventually transferred back to PICU on the same day. Mr. A continued to refuse psychotropic agents but accepted levothyroxine after much persuasion. In addition, he was treated with aggressive oral fluid resuscitation. With treatment, Mr. A's free T₄ and triiodothyronine levels normalized, and TSH levels were in a downward trend. Quite interestingly, his CK levels also normalized, and there was resolution of both his physical and psychiatric symptoms. This outcome provides evidence that hypothyroidism may account for rhabdomyolysis accompanied by psychiatric symptoms. Mr. A did not receive any neuroleptics for his aggression in view of elevated CK levels, and he refused to take valproic acid and lorazepam, which were recommended to address his impulsivity, irritability, and aggression.

Hypothyroidism may cause rhabdomyolysis and present with psychiatric symptoms, which may go unnoticed.^2–6 Mentally ill patients can have significant comorbid medical illnesses that may have a cause-effect relationship with the mental illnesses, as well. The agitation should not be automatically attributed to underlying psychiatric condition, and the necessary medical workup should not be withheld, as illustrated by this case report.