Reninoma is a rare, benign adrenal tumor that produces high levels of renin, a hormone that regulates blood pressure. However, there are a few synonyms for the term reninoma, including juxtaglomerular cell tumor, renin-secreting tumor, and renin-producing tumor. Juxtaglomerular cell tumor refers to the location of the tumor, which is in the juxtaglomerular cells of the kidney. Renin-secreting tumor and renin-producing tumor both refer to the function of renin production, which is the defining characteristic of the tumor. Although rare, reninomas can cause severe hypertension and electrolyte imbalances and may require surgical intervention.