Usefulness of atrial natriuretic peptide assay in primary aldosteronism.

Atrial natriuretic peptide (ANP) can be elevated in conditions which are characterized by increased atrial pressure and or expanded plasma volume. We and others have previously shown a significant increase of ANP plasma levels in a small number of patients with primary aldosteronism. In this study we have extended the assay of plasma ANP to a larger number of patients. We studied ANP plasma levels before and after upright posture and acute sodium load in 16 patients with aldosteronoma (APA) and 13 with idiopathic aldosteronism (IHA). The study was repeated also after the removal of aldosteronoma. In patients with primary aldosteronism, the mean supine ANP plasma level was significantly higher than in the age matched normal subject group; supine ANP was significantly higher in the APA than in the IHA group. The decrease of ANP levels after upright posture was significant in both groups. The ANP increase after acute saline load was similar in APA and in IHA. After the removal of aldosteronoma ANP values returned to normal. In conclusion, it is confirmed that plasma ANP levels are elevated in primary aldosteronism and could reflect a greater volume expansion in patients with APA. Despite this difference, ANP still responds to physiological stimuli in both groups. Finally, ANP measurement can provide an additional tool in the differential diagnosis between APA and IHA.

Hypertensive congenital adrenal enzymatic defects detected by high-performance liquid chromatography of corticosteroids.

The simultaneous measurement of the adrenal deoxycorticosterone (DOC), 18-OH-DOC, corticosterone (B), 18-OH-B, 11-deoxycortisol (S) and cortisol (F) present in human plasma in cases of adrenal dysfunction was accomplished using a high-performance liquid chromatographic (HPLC) system with a UV detector and with a radioimmunoassay (RIA). After a solid-phase extraction, plasma samples were separated by HPLC using a gradient of water-acetonitrile-ethanol on a radial compressed reversed-phase column. In a 70-min cycle, a complete separation of adrenal steroids was accomplished. The UV detector allowed direct measurement of F in each plasma sample while in selected cases B and S were directly determined. It was therefore possible quickly to identify patients with hypertensive congenital adrenal enzymatic defects with this method: the 17-alpha-hydroxylase deficiency characterized by the absence of measurable levels of F with an evident peak corresponding to B and the 11-beta-hydroxylase deficiency in which high levels of S without F are detected. The RIA of DOC, B, 18-OH-DOC and 18-OH-B complete the characterization of the adrenal defect. Therefore, with this HPLC method it is possible to recognize the major hypertensive adrenal enzymatic deficiencies such as the defect of 17-alpha-hydroxylase or 11-beta-hydroxylase. With "RIA" detectors an almost complete spectrum of adrenal steroid secretion can be obtained.