Statins or other medication-induced rhabdomyolysis: Given the patient's age, it is likely that she is on multiple medications, including statins, which are known to cause rhabdomyolysis, especially when combined with other drugs like gemfibrozil.

Severe dehydration or heat stroke: Elderly individuals are more susceptible to dehydration and heat-related illnesses, which can lead to rhabdomyolysis.
Trauma or prolonged immobilization: Falls or other traumatic events can cause muscle damage, and prolonged immobilization can lead to rhabdomyolysis, especially in the elderly.
Electrolyte imbalance (e.g., hypokalemia, hypophosphatemia): Electrolyte disturbances can contribute to muscle damage and rhabdomyolysis.
Infections (e.g., bacterial, viral): Certain infections, such as Legionnaires' disease or influenza, can cause rhabdomyolysis.

Compartment syndrome: A medical emergency that requires prompt intervention to prevent permanent muscle damage.
Neuroleptic malignant syndrome (NMS): A life-threatening condition associated with the use of neuroleptic medications, which can cause rhabdomyolysis.
Malignant hyperthermia: A rare but potentially fatal condition triggered by certain anesthetics or muscle relaxants.

Muscle dystrophies (e.g., Duchenne, Becker): While rare in a 67-year-old female, some forms of muscular dystrophy can present later in life.
Glycogen storage diseases (e.g., McArdle disease): Rare genetic disorders that affect muscle glycogen metabolism and can cause rhabdomyolysis.
Inflammatory myopathies (e.g., polymyositis, dermatomyositis): Autoimmune conditions that can cause muscle inflammation and damage.
Toxin-induced rhabdomyolysis (e.g., snake venom, certain drugs): Exposure to certain toxins can cause muscle damage and rhabdomyolysis.