Case Presentation: A 71 year old female with past medical history of DM2, HTN, and CKD presented with weakness and body aches, progressing to inability to ambulate. Home medications included insulin, valsartan, and rosuvastatin. She was found to have a creatinine of 7.99 mg/dL from a baseline of 2 mg/dL. She was also found to have creatine kinase (CK) of >20,000 U/L. Nephrology team was consulted and the patient was initiated on dialysis in the setting of acute renal failure from rhabdomyolysis. The patient had weakness mainly of her lower extremities causing inability to ambulate. Rheumatology team was consulted inpatient due to concern for myositis. MRI of her bilateral thighs showed diffuse edema of the musculature and deep fascial planes consistent with myositis. The patient had a muscle biopsy which showed myopathic changes most consistent with statin-induced necrotizing myopathy and rhabdomyolysis. An extensive myositis panel, including anti-HMG-CoA reductase antibodies, was negative. Due to initial concern for autoimmune myositis, the patient was at first started on a course of prednisone which was tapered off after biopsy results. The patient continued on dialysis while inpatient with close nephrology follow-up. Her CK downtrended after stopping rosuvastatin and her weakness improved with return to independent ambulation.
Discussion: Statin class medications are commonly used cholesterol-lowering agents with benefits of treatment and prevention of cardiovascular disease. Statin-associated muscle symptoms (SAMS) are well known side effects, with approximately 10-25% of patients in clinical practice experiencing muscle problems (5). SAMS are typically divided into four categories: myalgias or mildly elevated CK, self-limited toxic myopathy, rhabdomyolysis, and immune-mediated necrotizing myopathy (2).Rhabdomyolysis is characterized by muscle necrosis and release of intracellular muscle contents into systemic circulation. Rhabdomyolysis can range from asymptomatic CK elevation to acute renal failure. The FDA Adverse Event Reporting System reports rates of statin-induced rhabdomyolysis at 0.3-13.5 cases per 1,000,000 statin prescriptions (6). Risk factors for higher likelihood of statin-induced rhabdomyolysis include age, renal/hepatic/thyroid dysfunction, and hypertriglyceridemia (7). A rare form of myopathy is statin-induced necrotizing autoimmune myopathy (SINAM), which is an autoimmune myopathy characterized by the presence of anti-HMG-CoA reductase antibodies present in 94% of cases (3).The mainstay management of statin included rhabdomyolysis is immediate discontinuation of the drug. In cases of severe kidney injury, initiation of dialysis should be considered. Patients with a history of statin induced rhabdomyolysis should generally not be placed on another statin because of the risk of recurrence (7). For patients on statins with possible SAMS symptoms, several diagnostic tools exist for determining the likelihood of SAMS versus non-specific muscle symptoms. One of these is the Statin-Associated Muscle Symptoms-Clinical Index (SAMS-CI) score, which categorizes symptoms as probable, possible, and unlikely (3).
Conclusions: Practitioners should remain vigilant about the possible adverse effects of statin medications in light of how commonly prescribed they are. If patients develop muscle symptoms, the spectrum of SAMS including rhabdomyolysis and necrotizing myopathy should be considered and investigated prior to continuing the medication.