TOD indicates target organ damage (eg, cerebrovascular disease, hypertensive retinopathy, left ventricular hypertrophy, left ventricular dysfunction, heart failure, coronary artery disease, chronic kidney disease, albuminuria, peripheral artery disease). Table 13. Causes of Secondary Hypertension With Clinical Indications and Diagnostic Screening Tests Prevalence Clinical Indications Physical Examination Screening Tests Additional/Confirmatory Tests Common causes Renal parenchymal 1% 2% Urinary tract infections; obstruction, hematuria; urinary frequency and nocturia; analgesic abuse; family history of polycystic kidney disease; elevated serum creatinine; abnormal urinalysis Abdominal mass (polycystic kidney disease); skin pallor Renal ultrasound Tests to evaluate cause of renal disease Renovascular Resistant hypertension; hypertension of abrupt onset or worsening or increasingly difficult to control; flash pulmonary edema (atherosclerotic); early-onset hypertension, especially in women (fibromuscular hyperplasia) Abdominal systolic- diastolic bruit; bruits over other arteries (carotid atherosclerotic or fibromuscular dysplasia), femoral Renal Duplex Doppler ultrasound; MRA; abdominal CT Bilateral selective renal intra-arterial angiography Primary 8% 20% Resistant hypertension; hypertension with hypokalemia (spontaneous or diuretic induced); hypertension and muscle cramps or weakness; hypertension and incidentally discovered adrenal mass; hypertension and obstructive sleep apnea; hypertension and family history of early-onset hypertension or stroke Arrhythmias (with hypokalemia); especially atrial fibrillation Plasma aldosterone/ renin ratio under standardized conditions (correction of hypokalemia and withdrawal of aldosterone antagonists for 4 6 wk) Oral sodium loading test (with 24-h urine aldosterone) or IV saline infusion test with plasma aldosterone at 4 h of infusion Adrenal CT scan, adrenal vein sampling. 