Validated low-volume aldosterone immunoassay tailored to GCLP-compliant investigations in small sample volumes

INTRODUCTION Heart failure is well investigated in adults, but data in children is lacking. To overcome this shortage of reliable data, appropriate bioanalytical assays are required. OBJECTIVES Development and validation of a bioanalytical assay for the determination of aldosterone concentrations in small sample volumes applicable to clinical studies under Good Clinical Laboratory Practice. METHODS An immunoassay was developed based on a commercially available enzyme-linked immunosorbent assay and validated according to current bioanalytical guidelines of the EMA and FDA. RESULTS The assay (range 31.3-1000 pg/mL [86.9-2775 pmol/L]) is characterized by a between-run accuracy from - 3.8% to - 0.8% and a between-run imprecision ranging from 4.9% to 8.9% (coefficient of variation). For within-run accuracy, the relative error was between - 11.1% and + 9.0%, while within-run imprecision ranged from 1.2% to 11.8% (CV). For parallelism and dilutional linearity, the relative error of back-calculated concentrations varied from - 14.1% to + 8.4% and from - 7.4% to + 10.5%, respectively. CONCLUSIONS The immunoassay is compliant with the bioanalytical guidelines of the EMA and FDA and allows accurate and precise aldosterone determinations. As the assay can run low-volume samples, it is especially valuable for pediatric investigations.