Ans is option 1 HRCT The usual screening test is to measure the serum potassium level. If it is low, diagnostic tests are done including measuring blood and urinary aldosterone levels and blood renin levels. In Conn's syndrome, the aldosterone is elevated and the renin is suppressed. If these tests are diagnostic then imaging studies are done to see if a tumor can be localized. Since these tumors are small they can be hard to find even with the best CT or CT with contrast or MRI scan. Some patients may have no obvious radiographic tumor but one adrenal is affected (unilateral primary adrenal hyperplasia) and they can benefit from surgical removal. Other patients may have both adrenals affected with no visible tumor (idiopathic hyperaldosteronism) and surgery will not help. In these situations blood has to be drawn from each adrenal vein (so called adrenal venous sampling) in order to measure aldosterone levels to be sure which adrenal has the tumor. The symptoms of hyperaldosteronism may resemble other conditions or medical problems. Always consult your physician for a diagnosis. the diagnostic procedures for aldosteronoma may include: Blood and urine tests to measure potassium and hormone levels Computed tomography (CT or CAT scan) or magnetic resonance imaging (MRI) - are non-invasive procedures that take cross-sectional images of the adrenal or other internal organs; to detect any abnormalities that may not show up on an ordinary x-ray Adrenal venous sampling- an invasive test performed by a radiologist where a catheter is placed in the adrenal veins to measure the hormone level and confirms the tumor location. Ref Harrison 17/e p2260 , Semantischolar.org