Clinical Chemistry, Vol 37, 1868-1879, Copyright © 1991 by American Association for Clinical Chemistry

Clinical evaluation and differential diagnosis of the individual hypertensive patient

FB Mueller and JH Laragh
Cardiovascular Center, New York Hospital, Cornell Medical Center, NY 10021.

This paper attempts to define the theory and practice of a modern approach to the initial workup of the patient with hypertension. The process includes a complete general medical evaluation along with special measures to enable the fullest characterization and clinical differentiation of the disease. The initial workup aims to (a) establish that the hypertension is sustained and should be treated; (b) identify all definable and curable causes for the hypertension; (c) identify the presence and degree of attendant risk factors such as smoking, alcohol use, obesity, diabetes, and abnormal lipid metabolism; (d) characterize the hypertension in terms of its pathophysiology; and (e) assess the presence and degree of target organ damage to the heart, brain, and kidneys. Because all diastolic hypertension is due to arteriolar vasoconstriction, a fundamental strategy of this process is to distinguish between renin-mediated and sodium-related vasoconstrictive forces and to evaluate which is preponderant. The chief instruments of this strategy are the renin-sodium profile and the response of plasma renin activity and blood pressure to specific antirenin system drugs. The captopril test, an important protocol in making this distinction, is primarily a powerful screening tool for confirming the possible presence or absence of curable renovascular disease or curable primary aldosteronism. That renin profiling cannot accurately discriminate between the contributions of either the renin or sodium-volume factors in that large fraction of medium-renin patients is not a viable reason for not performing the test. The test has its greatest strength for identifying sizable numbers of otherwise unrecognizable patients with very high or very low renin concentrations who might have curable disorders and who likely reflect different pathophysiologic vasoconstrictive mechanisms for which entirely different drug therapies are appropriate. However, the baseline renin test is also useful for assessing prognosis and the likelihood of a heart attack and it is valuable for deciding whether to use an anti- renin system drug (for medium and high renin concentrations) as opposed to natriuretic agents (low-renin patients) such as a diuretic or calcium antagonists as the primary step. In our present state of knowledge, the basic diagnostic biochemical workup includes the renin- sodium profile and the 24-h urinary sodium, potassium, and microalbumin excretion rates. This package is further enriched by baseline electrocardiography and echocardiography and the evaluation of glucose and lipid patterns.(ABSTRACT TRUNCATED AT 400 WORDS)