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

Abstract

Background: Psoriatic arthritis is a chronic multisystem inflammatory disorder with various systemic diseases such as cardiovascular diseases, diabetes mellitus and metabolic syndrome. Renal involvement in patients with psoriatic arthritis is sparsely studied and its association is still unclear. This entity is called “Psoriatic Nephropathy”. RBP is a 21-kDa protein that is hepatically synthesized. And since it is low molecular weight protein it is freely filtered through the glomeruli and then almost completely reabsorbed in the proximal tubules, which makes this protein as useful biomarker of tubular renal impairment. 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 wer