An outline of steps in initial management
The presence of systolic–diastolic hypertension, or ISH, should be confirmed by several office measurements of blood pressure, preferably at more than a single visit, and in the supine as well as the erect posture. Ideally, a 24-hour recording of ambulatory blood pressure is done to exclude ‘white coat’ effect and to determine the circadian pattern of blood pressure increase. The status of pre-existing medical disorders will need assessment, particularly those that increase cardiovascular risk, such as diabetes mellitus, hyperlipidemia, and chronic renal failure.
As part of the routine clinical examination of the patient, renal and endocrine causes of hypertension should be excluded. Investigation for sleep apnea may also be required. The tests recommended are included in Table 2. Plasma concentrations of electrolytes, uric acid, creatinine, renin, and aldosterone should be measured before starting drug therapy. Increased plasma creatinine concentration indicates renal impairment: further investigation may be needed to determine whether this finding is caused by renal artery constriction or outflow tract obstruction, both potentially remediable conditions. Hyperuricemia denotes a risk that gout may be precipitated if diuretic therapy is given. Hypokalemia and/or a raised renin–aldosterone ratio suggest primary aldosteronism, which can cause resistant hypertension; these findings would prompt a 24-hour collection of urine for determination of urinary aldosterone excretion rate, and further tests to detect a possible adrenal adenoma. Urinary catecholamines are measured if pheochromocytoma is to be excluded. Urinary microscopy and a renal ultrasound help in detection of underlying renal parenchymal disease or renal outflow obstruction. If an epigastric bruit is heard, or if there is disparity in renal size, computed tomography examination of the renal arteries may be required to exclude renal artery stenosis. If there is a history of daytime drowsiness or sleep disturbance, overnight oximetry should be done to exclude obstructive sleep apnea.