A51-year-old female is referred to your office after her pcp incidentally found a left adrenal mass of 2.8 cm in diameter on an abdominal computed tomography that was ordered to evaluate right lower abdominal discomfort (which has since resolved). she reports no sweating, palpitations, headache, weight gain, or proximal muscle weakness. her medical history is notable only for hypertension that has been well controlled with lisinopril, at a dose of 20 mg daily. on exam her body mass index is 30. there is no evidence of abnormal fat distribution or striae. abdominal examination shows no masses or tenderness to palpation. heart and lung exams are unremarkable and there is no peripheral edema. the remainder of the examination is normal. what is the next best step in management of this patient?