Analytical evaluation and bioclinical validation of new aldosterone and renin immunoassays

Aldosterone and renin determinations play an important role in the etiological diagnosis of secondary hypertension. The analytical performances of new aldosterone and renin immunoassays on the Lumipulse G600II^® system (Fujierbio) were investigated and compared with those of the iSYS^® system (IDS) on patients concerned by medical investigations in a context of suspected or proven Primary aldosteronism.

By using the Lumipulse^® G Aldosterone and Renin assays we performed imprecision study, linearity and method comparison (n=107). Accuracy of this new renin assay was tested using the International Standard (WHO IS 68/356). We also assessed the equivalence of the different samples types (n=29).

The imprecision evaluation showed all CVs <3% and <6% for Lumipulse^® G Aldosterone and Renin assays respectively. The linearity was excellent over the clinical range and the comparison with the iSYS^® assays (n=79) showed a strong correlation (R²=1) despite a slight tendency to underestimation (bias of -17.53 pg/mL or 48.56 pmol/L for aldosterone and -15.395 pg/mL for renin). Moreover, the contingency studies based on diagnostic criteria showed that Lumipulse^® G results lead to the same clinical diagnosis that iSYS^® results. A clear correlation was obtained between EDTA and heparin plasma as well as with the serum for all range of measures.

The Lumipulse^® G Aldosterone and Renin assays present performances compatible with a routine use in medical laboratories. The precise quantification in the low range can be of interest in some clinical contexts especially standing/laying tests. However, the standardisation against the WHO International Standard Renin would be advisable.