Figure 4.

Percent difference in aldosterone concentration by assay type under conditions of angiotensin II modulation (A) and ACTH modulation (B), ordered from lowest to highest aldosterone concentration. All samples obtained under conditions of oral sodium suppression and dietary sodium restriction to modulate angiotensin II were pooled (A: red, oral sodium suppression; blue; sodium restriction) and all samples obtained under ACTH modulation were pooled (B; green: dexamethasone suppression; orange, ACTH stimulation). Each participant sample is represented, ordered from the lowest to highest aldosterone concentration by immunoassay. The vertical bars represent the percent difference between immunoassay and LC-MS/MS (liquid chromatography–tandem mass spectrometry) as a proportion of the immunoassay aldosterone concentration, with positive values indicating a higher immunoassay and lower LC-MS/MS result.