Micro-albuminuria and Urinary Retinol Binding Protein as Markers of Subtle Renal Injury in Visceral leishmaniasis: Sensitivity, Specificity and predictive value of the immuno-turbidimetric technique

Abstract

Visceral leishmaniasis (VL) caused by L.donovani is endemic over several parts of Sudan and is a major cause of morbidity and mortality. It is characterized by fever, weight loss, pancytopenia, hepato-splenomegaly, lymphadenopathy and can be complicated by acute renal damage. Deposition of immune complexes and renal infiltration by infected macrophages can result in glomerulonephritis, tubulo-interstitial nephritis and proximal tubulopathy. While sodium stibogluconate (SSG) is the mainstay of treatment, recent reports of resistance emergence, prompted the search for alternative drugs and the use of drug combinations. Paromomycin® (PM), an amino glycoside antibiotic that is under assessment as an alternative treatment for VL is known to be nephrotoxic. The nephrotoxicity is dose related. Microalbuminuria (MA) and urinary Retinol Binding Protein (urRBP) are usually seen in 40-75% of VL patients and are considered as useful markers of glomerulonephritis and tubular dysfunctions respectively. Immunoassays have played vital roles in diagnosing diseases, monitoring the level of the humoral immune response, and identifying molecules of biological or medical interest. These assays differ in their speed, specificity and sensitivity; some are strictly qualitative, others are quantitative. Enzyme-Linked Immunosorbent Assay (ELISA or EIA), depends on an enzyme that is conjugated with an antibody and reacts with a colorless substrate to generate a colored reaction product. These assays are sensitive and have the advantage of being safe and less costly. The immunoturbidimetric technique is simple, rapid and easy 9 to perform and is sensitive enough to detect an even slightly increased urinary albumin excretion.