Secondary hypertension

A 47-year-old man presents to the office for a blood pressure check. He has had hypertension for at least 7 years, impaired glucose tolerance, and obstructive sleep apnea. Current medications include lisinopril 40 mg daily, metoprolol 25 mg twice daily, amlodipine 10 mg daily, hydrochlorothiazide 12.5 mg daily, and metformin 500 mg twice daily. On examination, BP is 170/95 mmHg, pulse 80/min, respiratory rate 16/min, and temperature 98.7 °F. He is obese with BMI 35. Funduscopic examination shows mild arteriolar narrowing without hemorrhages, jugular veins are not distended, lungs are clear, cardiac examination discloses an S4 gallop, and he has 1+ leg edema. Laboratory evaluation shows hemoglobin 13.7 g/L, hematocrit 40 %, white blood count 7.6, Na 137 meq/L, K 3.6 meq/L, Cl 100 meq/L, 30 meq/L, BUN 27 mg/dL, creatinine 1.4 mg/dL, glycosylated hemoglobin 6.9 %, and urinalysis shows 100 mg% protein without cells.