Renal hypertension causes systemic hypertension and thus has serious consequences if left untreated. It is diagnosed by assessing the patient's history, risk factors, physical findings, laboratory tests, and imaging studies.
Renal hypertension, a cause of systemic hypertension, is the result of stenosis or occlusion in the renal artery/arteries and the subsequent under perfusion of one or both kidneys . 90% of cases are caused by atherosclerotic renal artery stenosis (ARAS), which affects males above the age of 50 years while the remaining are secondary to fibromuscular dysplasia (FMD), which is commonly found in younger women  .
While some patients are asymptomatic, headache is the most frequent manifestation in others. Further complaints include emesis, visual disturbances, and changes in the mental status. If the patient has developed congestive heart failure, the clinical presentation consists of fatigue, dyspnea on exertion, peripheral edema, palpitations, and other associated symptoms . Moreover, individuals with renal disease are likely to exhibit hematuria and edema .
There are numerous risk factors for renal hypertension such as malignant hypertension, progressive renal impairment, diastolic blood pressure greater than 120 mm Hg, hypertension unresponsive to multidrug therapy, and worsening blood pressure with diuretic use. Furthermore, hypertension accompanied by proteinuria and azotemia is another risk.
Patients with renal hypertension typically have a history of 1) a sudden increase in blood pressure, 2) onset of hypertension in the absence of risk factors, 3) worsening of previously controlled hypertension, 4) repeat episodes of pulmonary edema, 5) unprovoked hypokalemia, 6) generalized atherosclerosis in older individuals, and/or 7) smoking,
Sequelae include chronic hypertension, kidney disease, renal failure, heart failure, seizures, encephalopathy, coma, and even death. Also, end-organ damage is a concern especially in the setting of chronic kidney disease  .
Individuals with a clinical presentation or a history as described above warrant a full workup. The assessment consists of the patient's personal and family history, physical exam, and the appropriate studies.
The patient's blood pressure and other vitals must be assessed with the proper techniques in order to ensure accuracy. Very importantly, the patient should be examined carefully. One remarkable finding in nearly 50% of affected individuals is an abdominal bruit, especially when present during both diastole and systole  .
Target-organ effects of chronic hypertension should also be investigated. For example, patients with heart failure will exhibit peripheral edema and other cardiovascular signs while those with ophthalmologic manifestations will have retinal hemorrhages and retinopathy.
A complete blood count (CBC) and a complete metabolic panel (CMP), which includes electrolyte levels and renal function tests, are important components of the workup . Fasting glucose and fasting lipid tests are indicated in children with chronic kidney disease, individuals with severely elevated blood pressures, and other groups as well . To examine rare causes of hypertension, a 24-hour urine collection can be used to measure creatinine, electrolytes and other metabolites .
Intra-arterial digital subtraction angiography (DSA) is currently recommended as the initial study in the assessment of renal artery stenosis, especially in patients with renal impairment. Along with DSA, renal arteriography is also the gold standard diagnostic technique.
Magnetic resonance angiography (MRA) offers critical information regarding the renal arteries, their branches, anatomic variants, distal stenosis, and any suspicious masses. One meta-analysis study reports that gadolinium-enhanced MRA is associated with a 97% sensitivity and 85% specificity for detection of renal artery stenosis . Computed tomographic angiography (CTA) is also another technique used to diagnose stenosis.
Multidetector contrast tomography (MDCT) provides details about the renal artery and parenchyma of the kidneys as well nearby structures . Another study is doppler ultrasonography, which allows for the evaluation of the anatomy and function of the renal arteries. This modality is associated with good sensitivity and specificity for detection of stenosis . Additionally, a nuclear renal scan can be used to determine if a patient will benefit from surgery . This test can be used with captopril for enhancement.