Table 2.

Comparison of different immunoassays. Median aldosterone concentration before (0 h) and after (4 h) saline infusion by RIA (n = 81) and chemoluminescence assay (CLIA, n = 106). Data are given as median and interquartile range. PA subtypes (APA and BAH) were not definitively determined in 22 patients with PA.

	n	Aldosterone (ng/L) during the SIT
		0 h			4 h
		Coat-a-count® RIA	IDS-iSYS aldosterone® CLIA	P-value	Coat-a-count® RIA	IDS-iSYS aldosterone® CLIA	P-value
EH	84	92 (71–131)	86 (44–146)	0.414	33 (25–48)	37 (37–40)	0.195
PA	103	210* (147–313)	265* (158–384)	0.235	120* (80–190)	171* (101–246)	0.027
APA	57	192 (146–367)	269 (183–376)	0.092	154 (77–191)	175 (119–329)	0.109
BAH	24	153 (139–292)	276 (157–387)	0.290	111 (79–154)	171 (98–242)	0.108

*P < 0.001 vs EH (Mann-WhitneyU-test).

APA, aldosterone-producing adenoma (RIA: n = 23, CLIA: n = 34); BAH, bilateral adrenal hyperplasia (RIA: n = 9, CLIA: n = 15); EH, essential hypertension (RIA: n = 37, CLIA: n = 47); PA, primary aldosteronism (RIA: n = 44, CLIA: n = 59).