LAUSR

Objective: Direct plasma renin (DPR) has a much broader distribution than plasma renin activity (PRA). The finding in one patient of extremely high DPR values without apparent cause led us to the diagnosis and successful treatment of renovascular hypertension which had been initially ruled out by magnetic resonance angiography. Design and method: Review of the patient’s clinical records and the relevant literature. Results: A 39-year-old woman, long-term user of oral contraceptives was referred to our Hypertension Clinic. For the last two years she had presented severe hypertension, with BP often > 200/120 mmHg, poorly responding to antihypertensive drugs including ACEI or ARB plus calcium antagonists, diuretics, spironolactone, doxazosin and bisoprolol. She reported frequent holocranial non-pulsatile headaches without pallor, tachycardia, nausea or other vegetative symptoms. Laboratory testing was normal except for albuminuria (378 mg/g Cr) with normal plasma creatinine,eGFR, potassium, TSH and ACTH. Blood pressure remained high after contraceptive withdrawal. Physical examination showed only grade I overweight. ABPM showed diurnal 198/96 mmHg and nocturnal 186/89 mmHg, non-dipper without marked highs or lows. Echocardiography showed moderate LVH but ruled out heart failure. All drugs except diltiazem and doxazosin were withdrawn for a month, plasma metanephrines and cortisol suppression were normal, and plasma aldosterone was in the upper normal range (29.6 ng/dL) while DPR was extremely high (2196 mU/L, normal upper limit 39 mU/L). Renovascular hypertension (or reninoma) was suspected, but magnetic resonance renal angiography was informed as normal. However, the left kidney was significantly smaller and hypoperfused. A standard renal angiogram showed fibromuscular dysplasia with severe left stenosis. Angioplasty was performed, and after 3 months the patient’s blood pressure is well controlled with 120 mg slow-release diltiazem daily, and her plasma angiotensin and renin are normal. Conclusions: DPR can be raised by low-salt diet, hypovolemia, drugs such as diuretics, ACEIs and ARBs, hyperthyroidism, pheochromocytoma/paraganglioma and edematous states (heart or liver failure, nephrotic syndrome). However these conditions are unlikely to cause extremely high renin. Renovascular hypertension or reninoma should be suspected, even when the initial imaging seems negative. Fibromuscular dysplasia is likelier than atherosclerotic stenosis or reninoma in contraceptive users.