Sublingual nifedipine can cause uncontrolled pressure reductions that compromise organ perfusion. Temporizing by calling consultants or ordering diagnostic studies as first maneuvers delays effective intervention and can be fatal. Kaplan NM, Clinical Hypertension, Fifth Edition, Williams and Wilkins, Baltimore, 1990. Normal ranges for plasma renin activity are established in untreated subjects. Diuretics, ACE inhibitors and direct-acting vasodilators all raise circulating levels of renin, and the degree of elevation, while variable from patient to patient, can clearly result in values that exceed the normal range.
Exogenous estrogens can also contribute to elevated plasma renin activity.
In the present situation, with well-controlled blood pressure and no other reason to suspect renovascular disease, there would be no reason to pursue the diagnosis. A beta blocker might lower the renin, but it is unnecessary for treatment of the hypertension in this patient. Kaplan NM, Clinical Hypertension, Fifth Edition, Williams and Wilkins, Baltimore, 1990. Malignant hypertension is uncommon in the elderly and clearly would not be seen at this level of blood pressure. Elderly patients are susceptible to hyponatremia when treated with thiazide diuretics, and this idiosyncratic drug reaction should be sought by monitoring serum electrolytes after institution of these agents, particularly if symptoms compatible with hyponatremia are reported.