The most likely diagnosis is statin-induced rhabdomyolysis associated with atorvastatin therapy as a cause of this patient's acute kidney injury (AKI). This is supported by her symptoms of muscle weakness, physical examination findings, AKI, and urinalysis with blood but no erythrocytes. Myoglobin released from damaged muscle cause renal tubular obstruction, direct nephrotoxicity, intrarenal vasoconstriction, and AKI. Statin-induced rhabdomyolysis is a rare occurrence, and routine testing of muscle enzymes following initiation of statin therapy is not recommended. However, further evaluation is indicated in patients presenting with suggestive symptoms and clinical findings, as in this patient. Risk factors for development of statin-induced myositis include advanced age, female gender, preexisting chronic kidney disease (CKD), diabetes mellitus, hypothyroidism, high-dose statin therapy, and use of medications metabolized through cytochrome P450 3A4, which may increase serum levels of statins (lovastatin, simvastatin, atorvastatin) metabolized through this pathway. Treatment includes discontinuation of the statin, hydration, and management of any associated electrolyte abnormalities.

Hydrochlorothiazide can cause symptoms of weakness from volume depletion, hyponatremia, or hypokalemia. This patient has no evidence of volume depletion on examination, and her serum potassium level is elevated. Although she has hyponatremia, it is mild and does not explain her symptoms or urinalysis findings.

Although hypothyroidism may be associated with myalgia and elevations of serum muscle enzymes, rhabdomyolysis is rare, and initiation of levothyroxine therapy is not associated with worsening muscle symptoms. This patient's lack of myalgia at the time of hospitalization and mild degree of hypothyroidism make hypothyroid myopathy an unlikely diagnosis.

ACE inhibitors such as lisinopril can cause AKI in certain settings such as hypovolemia or renal artery stenosis. However, this patient's clinical presentation and laboratory findings are not consistent with AKI associated with ACE inhibitor therapy.