Background/Purpose:

Lupus nephritis (LN) develops in 50-60% of lupus patients. The consequence of this entity is renal failure, that can arise in 10-15% of patients and an increase of the hazard ratio for mortality (HR 2.28). Proliferative lupus nephritis is the most aggressive clinical form. The criteria for diagnosis of LN are easy to apply, but not specific for determine the class of LN.

The aim of the study was to find a metabolomic profile in the urine of lupus patients to diagnose proliferative and/or membranous classes of LN.

Methods:

This was a cross-sectional study. We included lupus patients with and without proliferative and/or membranous lupus nephritis. We used urine samples for the detection of metabolites using mass spectrometry thru gas chromatography (coupled with electronic nose). For baseline characteristics we used t test or U Mann Whitney depending on the distribution of the variables; and X2 for categorical variables. For the detection and selection of the metabolites we used principal component analysis and random forest.

Results:

We included 73 lupus patients, 35 had lupus nephritis; in this group the most common class of LN was IV.

The patients with lupus nephritis were younger and had higher SLE activity at baseline. Sex distribution between the groups were similar. Due to the severity of the disease more patients with LN received steroid and cyclophosphamide pulses.

In the preliminary results of metabolomics we found 242 metabolites, of which 15 were match lupus nephritis, and thus can be considered as a metabolomic fingerprint.

Conclusion:

These preliminary results show a viable method for obtaining new biomarkers for the diagnosis of the different lupus nephritis classes.