Review Question - QID 214549

A 56-year-old man presents to the emergency department after a fall. He was walking with his friend and subsequently fell onto his friend, who gently laid the patient on the ground, preventing head injury. Prior to the fall, the patient denied feeling lightheaded, having vision changes, or palpitations. When he was on the ground, the patient was not responsive to voice. There were no abnormal movements when he was unconscious, and the patient regained consciousness in approximately 2 minutes. He was not confused afterward and denied having any bowel or bladder incontinence or tongue biting. He reports currently feeling well without chest pain, shortness of breath, or palpitations. He has a history of hypertension, hyperlipidemia, and a myocardial infarction 1 year ago, requiring drug-eluting stent placement. His blood pressure is 135/85 mmHg, pulse is 85/min, and respirations are 16/min. His physical examination is unremarkable. An electrocardiogram demonstrates normal sinus rhythm with Q waves in the anterolateral leads. His laboratory results are shown below:

Serum:
Na+: 140 mEq/L
Cl-: 98 mEq/L
K+: 3.8 mEq/L
HCO3-: 24 mEq/L
BUN: 15 mg/dL
Glucose: 102 mg/dL
Creatinine: 0.9 mg/dL
Ca2+: 9.5 mg/dL
Mg2+: 1.8 mEq/L

Which of the following is the most appropriate next step in management?