Effect of age on hypertension: analysis of over 4,800 referred hypertensive patients.

We evaluate in this study the factors associated with the effect of age on blood pressure in more than 4800 patients. Their physicians referred them to evaluate for secondary causes for their hypertension. Factors studied included history and physical examination, serum sodium, potassium and creatinine, a stimulated plasma renin and catecholamine. We also studied the blood pressure response to infusion of either saralasin (an angiotensin II analogue) or enalapril (an angiotensin converting enzyme inhibitor), and plasma aldosterone and cortisol after infusion of saline. We measured serum thyroxin and thyroid stimulating hormone concentrations on 1061 consecutive patients in this series. The results of our study show that increased age is associated with a significant increase in the prevalence of hypertension and especially of systolic hypertension after age 60 years. Increased obesity between age 30-50 years is associated with significant increases in diastolic blood pressure and this trend is also seen in African-Americans who are heavier than whites. Increased age is associated with an increased prevalence of secondary forms of hypertension including atherosclerotic renovascular hypertension, renal insufficiency and primary hypothyroidism.