Approach to the Patient: Reninoma

Abstract

A reninoma is a functional tumor of afferent arteriolar juxtaglomerular cells that secretes the enzyme renin, leading to hyperactivation of the renin-angiotensin-aldosterone system. Reninoma is a potentially curable cause of pathological secondary hyperaldosteronism that results in often severe hypertension and hypokalemia. The lack of suppression of plasma renin contrasts sharply with the much more common primary aldosteronism, but diagnosis is often prompted by screening for that condition. The major differential diagnosis of reninoma is renovascular hypertension. Fewer than 200 cases of reninoma have been described. Reninomas have been reported across a broad demographic but have a 2:1 predilection for women, often of childbearing age. Aldosterone receptor blockade, angiotensin-converting enzyme inhibitors, or angiotensin receptor blockers offer effective medical management but are contraindicated in pregnancy, so surgical curative resection is ideal. The current optimal imaging and biochemical workup of reninoma and management approach (ideally, tumor excision with subtotal renal resection) are described.

Keywords: juxtaglomerular cell tumor; renin; reninoma; secondary aldosteronism; secondary hypertension.

Figure 1.

Contrast computed tomography abdomen in venous phase of a 35-year-old woman investigated for reninoma demonstrating right renal cortical cyst (arrow).

Figure 2.

Renin-angiotensin-aldosterone-system. Reduced sodium delivery to the macula densa prompts COX2-mediated PG release from the macula densa, stimulating cleavage of prorenin to renin in activated juxtaglomerular cells. Renin cleaves the N-terminal of angiotensinogen to produce angiotensin I. ACE cleaves angiotensin I to produce angiotensin II, which acts vis ATR1 to stimulate aldosterone synthesis and secretion from the adrenal cortex, increases vascular tone, and closes the feedback loop by reducing renin production at the juxtaglomerular cell. Aldosterone acts via the MR in the distal tumor and collecting duct to reabsorb sodium and water, thereby expanding vascular volume. ACE, angiotensin-converting enzyme; ART-R, angiotensin II receptor type 1; B1-R, B1-adrenergic receptors; CAMP, cyclic adenosine monophosphate; COX2, cyclooxygenase 2; MR, mineralocorticoid receptor; PG, prostaglandin; SM, smooth muscle.

Figure 3.

Suggested preparation of patient to maximize sensitivity and specificity of renal vein sampling. IDC, indwelling catheter; IV, intravenous; PAC, plasma aldosterone concentration; PRC, plasma renin concentration; RAAS, renin-angiotensin-aldosterone system; RVS, renal vein sampling.