The role of urinary Retinol binding protein (RBP) as a novel biomarker in early detection of kidney affection in patients with psoriatic arthritis

Abstract

Abstract Background PsA is a chronic multisystem inflammatory disorder with various systemic diseases. Renal involvement in patients with PsA is sparsely studied and its association is still unclear. This entity is called “Psoriatic Nephropathy”. RBP has been proposed as the most sensitive marker for detection of renal tubule function loss. Aim We aim at early detection of renal tubular damage by measuring the level of urinary RBP as a novel biomarker in patients with psoriatic arthritis in relation to activity and severity. Methods We conducted a Cross-sectional study of 30 PsA patients from Physical Medicine, Rheumatology and Rehabilitation and Dermatology outpatients’ clinics at Ain Shams University Hospitals. They were subjected to full medical history taking and thorough clinical examination with calculation of DAS 28, PASI and HAQ scores. Full Laboratory evaluation included CBC, ESR, CRP, serum creatinine, BUN, SGOT, SGPT, urine analysis, estimated GFR (eGFR) and urinary RBP were measured for all the participants. The urinary RBP and eGFR were compared with 30 age and sex matched healthy controls. Results The urinary RBP mean±SD (ng/ml) was found to be 351.667±119.397 in patients and was statistically significantly higher in them than in controls 93.16±30.836 (t = 11.482, p < 0.001) and it was statistically significantly correlated with disease duration, disease activity according to DAS 28 and the severity of skin affection according to PASI score. While eGFR (ml/min) was found to be 131.729±28.943 in patients and it was statistically significantly lower in them than in controls 146.708±16.607 (t=-2.459, p = 0.017), however there was no statistically significant correlations with either DAS 28 or PASI scores. Conclusion Urinary RBP has been described as a novel biomarker in early detection of kidney affection and renal tubular damage in psoriatic arthritis patients.