RETINOL BINDING PROTEIN (RBP4) AS A URINARY MARKER OF SEVERITY IN CHRONIC KIDNEY DISEASE OF UNCERTAIN ETIOLOGY

Fernando,W.B.N.T¹.,Hettiarachchi, T.W¹., Hemage,R¹., Sudeshika S.H.T¹., Badurdeen, M.Z¹., Nanayakkara, N^2*

¹Centre for Education, Research and Training on Kidney Diseases (CERTKiD), Faculty of Medicine, University of Peradeniya, Sri Lanka

²Transplant and Dialysis Unit, Teaching Hospital, Kandy, Sri Lanka

Background:

RBP4 is a low molecular weight protein that is mainly synthesized in the liver belonging to the lipocalin superfamily. Its main function is to transport retinol (vitamin A). The role of urinary RBP4 as a biomarker of CKD in tubular diseases, glomerulopathies and transplantation is well established. Beyond the typical proximal tubulopathies, it has been shown that urinary RBP4 is associated with the severity of some forms of CKD

Objective:

The aim of the present study was to determine the level of urinary RBP4 as a marker of disease severity in CKD-u patients in Sri Lanka.

Methodology:

Thirty-nine biopsy-proven CKD-u patients who referred to Girandurukotte and Wilgamuwa hospital were studied. RBP4 level was measured in urine by MILLIPLEX MAG CERTKD panel 05 in a Luminex MAGPIX platform. All procedures were performed in accordance with the manufacturer’s instructions.

Results:

Separated serum was used to measure serum creatinine and the estimated Glomerular filtration rate (eGFR) was calculated. Patients were divided into stages according to their eGFR values. Stage distribution of the patients was stage 1- 6, stage 2- 12, stage 3- 15, and stage 4- 6. RBP4 results were analyzed using R statistical software. The median values of the RBP4 levels were stage1- 2762.5 pg/ml, stage 2- 7238.5 pg/ml, stage3- 50003 pg/ml and stage4- 61198.5 pg/ml. According to the results, the RBP4 level is increased with the stage. There is a negative correlation between the eGFR and the RBP4 level (-0.5362).

Conclusion:

Our results suggest that urinary RBP4 could be a marker of disease severity in CKD-u patients in Sri Lanka.

Financial assistance from the Ministry of Health and National Research Council Sri Lanka (Grant No TO 14-05 ) is acknowledged.

Keywords: Retinol Binding Protein, CKD-u, Marker of disease severity, eGFR