CT in the diagnosis of primary aldosteronism: sensitivity in 29 patients

The most common cause of primary aldosteronism is a small aldosterone-secreting adrenal adenoma. With improvements in CT technology, smaller adrenal lesions can now be detected. We reviewed our experience with 29 patients with primary aldosteronism to assess the sensitivity of CT in detecting aldosterone-secreting adenomas.

The records of all patients with biochemically proved Conn's syndrome who were referred for adrenal CT between 1982 and 1991 were reviewed. The CT examinations of each of these 29 patients were reviewed for evidence of hyperplasia or an adenoma. The interpretations were correlated with subsequent adrenal venous sampling (20 patients) or surgery (17 patients).

Fourteen of 17 aldosteronomas were detected on CT scans (sensitivity, 82%). Adrenal tumors were not seen on CT scans in any of the 12 patients with hyperplasia, although the glands appeared diffusely enlarged in only seven of these patients. In no case was an adrenal tumor seen on CT scans that was not found at surgery (positive predictive value, 100%).

If CT scans of patients with Conn's syndrome show a focal mass, ipsilateral adrenalectomy can be performed with the expectation of cure. If no mass is found, adrenal venous sampling can be used to detect an adenoma not shown on CT.