A 15-year-old boy has been immobilized in a double hip spica cast for 6 weeks after having fractured his femur in a skiing accident. He has become depressed and listless during the past few days and has complained of nausea and constipation. He is found to have microscopic hematuria and a blood pressure of 150/100 mm Hg. Which of the following is the most appropriate course of action?
a) Administer acetaminophen for pain
b) Begin a bisphosphonate
c) Increase fluid intake
d) Administer low-molecular-weight heparin