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 European Medicines Agency (EMA) and U.S. Food and Drug Administration (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 of 40 μL, it is especially valuable for pediatric investigations.