Case Presentation: 59 year-old female with past history of uncontrolled asthma with multiple exacerbations requiring systemic corticosteroids, and recurrent episodes of non-traumatic rhabdomyolysis, presented with muscle aches. On exam, patient was hemodynamically stable and afebrile, with bilateral upper and lower extremity tenderness. Laboratory analysis was concerning for elevated creatinine kinase levels of 1127 U/L. Complete metabolic panel, complete blood count, urinalysis and urine toxicology screen were noted without any abnormalities. Patient was diagnosed with non-traumatic rhabdomyolysis and started on intravenous fluids.Plasma 8 AM cortisol level of < 1.0 mcg/dl (reference range 10-20 mcg/dl) was noted. A high dose cosyntropin stimulation test was concerning for adrenal insufficiency. Morning Adrenocorticotropic hormone levels were noted to be < 5 pg/ml (reference range 10-60 pg/ml), thus ruling out primary and secondary causes of adrenal insufficiency. Concurrent laboratory values for anti-nuclear antibodies, myositis panel, erythrocyte sedimentation rate, C-reactive protein, aldosterone levels, thyroid stimulating hormone and plasma renin activity returned non-significant, thus ruling out autoimmune, infectious and other hormonal derangements as potential causes.Diagnosis of tertiary adrenal insufficiency secondary to chronic systemic corticosteroid use was made and patient was started on oral hydrocortisone. Patient showed improvement with therapy resulting in decreased hospital and emergency department visits.

Discussion: Rhabdomyolysis accounts for roughly 25,000 cases reported in the USA every year. (1) Traumatic rhabdomyolysis remains the leading cause, followed by non-traumatic etiologies such as medications, illicit drugs and infections. (1) (2) It is one of the top twenty leading causes of hospital admissions through the ED in the United States. (7) Endocrine disturbances are an uncommon cause of rhabdomyolysis, and muscle injury to the effect of rhabdomyolysis is a rare presenting symptom. Thus far only seven cases of Adrenal insufficiency presenting as rhabdomyolysis have been reported in literature. (4) Of these, most are cases of primary adrenal insufficiency and rest have been labelled due to secondary adrenal insufficiency. (4) Patients with primary and secondary adrenal insufficiency have been reported to present with concurrent hyponatremia in majority of the cases in literature, which confounds a direct relationship of cortisol to muscle injury. (5) Nearly half of the presented cases have comorbid endocrinopathies with deranged laboratory values, which further confound the picture of cause and effect. (5) Moreover, concurrent use of statins and fibrates have also been seen in such reports. (5)Our case is unique, as it is one of the only three reported cases of rhabdomyolysis due to tertiary adrenal insufficiency. A distinct feature of our patient was, that they had been hemodynamically stable with no electrolyte abnormalities on laboratory work up, consistently over the course of her hospital admissions in the past years.

Conclusions: Rhabdomyolysis is a common cause of hospital admissions throughout the United States. It is not unusual to find patients repeatedly coming in requiring hydration for elevated creatinine kinase levels. An index of suspicion is required for such patients, as the etiology can be beyond the conventional instances. Prompt diagnosis can decrease the burden of hospital re-admissions and further ailment to the patient.

IMAGE 1: Cosyntropin stimulation test

IMAGE 2: Creatinine Kinase trend through hospital stay