Renal biomarkers in current practice, urine albumin and serum creatinine, are inaccurate for early detection of Chronic Kidney Disease of uncertain etiology (CKDu) and discrimination of CKDu from other chronic renal diseases. Aim of the pilot study is to evaluate “fit for purpose” biomarkers or biomarkers that manifest in CKDu. Novel candidate renal biomarkers in clinical validation phase can be used for this purpose. Luminex xMAP, a robust analytical platform can assay multiple analytes in a small sample volume (< 50 µL) at picogram level that comply with this study. 80 biopsy proven stage 1-3 CKDu patients (Nanayakkara, 2011) were selected from renal clinics using a systematic sampling method. Urine and serum samples were collected and stored in -80°C refrigerator according to biological sample collection for clinical proteomics SOPs. Total of 27 renal candidate biomarkers were included in customized magnetic bead based multiplexed assay kits (four serum and two urine Millipore kits). Samples were prepared with duplicates of blank (1), standards (6), quality controls (2), and patients (39) on a 96 well microtiter plate, according to the manufacturer's instructions. Samples were analyzed on Luminex MAGPIX analyzer. The biomarker concentrations in the samples were determined from the 5-parameter logistic fit standard curves created in Milliplex analyst software. The manifestation of a biomarker in CKDu was deduced from number of samples within detectable range. The percentages for each biomarker was tested at 5% of significant level (Ho: P ≤ 0.8 Vs Ha: P > 0.8) to extract the biomarkers which exceeds significantly > 80% of cases within detectable range (One sample proportion test). Results of candidate renal biomarkers in 80 CKDu patientsTabled 1AnalyteDetectable Concentration Range% detected within range*min-DCmax-DCSerumTGF-β5.01 ρ3789 ρ100RBP-40.13 ρ18978 ρ0.00 (all > max-DC)β2MG0.035 ρ29453 ρ100Cystatin C0.062 ρ5283 ρ100NGAL0.05 ρ4442 ρ57 (43 > max-DC)TIMP-15.14 ρ655.91 ρ99Collagen-IV0.52 ρ988.42 ρ100IL-1013.10 ρ738.13 ρ21 (79 < min-DC)IL-62.45 ρ221.41 ρ29 (69 < min-DC)TNF R113.58 ρ6555 ρ96OPG5.27 ρ793.05 ρ96KIM-124.89 ρ865.44 ρ24 (76 < min-DC)Pentaxin-39.66 ρ4904 ρ96Renin86.04 ρ25632 ρ88PTH1.99 ρ251.98 ρ96FGF-2323.68 ρ1044 ρ34 (66 < min-DC)UrineNGAL0.0088 η559.32 η100RBP-40.043 η7511 η24 (76 > max-DC)β2MG0.56 η19252 η48 (52 > max-DC)Cystatin C0.02 η1981 η99OPN28.74 η2198 η99α1MG125.55 η42130 η83TIMP-10.25 η58.76 η93KIM-10.05 η1.34 η92FABP-18.49 η53.34 η49 (51 < min-DC)Collagen-IV018 η340.92 η100TFF-30.25 η1170 η99 Open table in a new tab * number of cases within detectable concentration (DC) as a percentage of the total number of cases, ρ = pg/ml, η = ng/ml. Serum (n = 10) TGFβ-1, β2MG, Cystatin C, TIMP-1, Collagen-IV, TNF RII, OPG, Pentaxin-3, Renin, PTH and urine (n=8) NGAL, Cystatin C, OPN, α1MG, TIMP-1, KIM-1, Collagen-IV, TFF-3 are fit for validation of CKDu. Serum IL-10, IL-6, KIM-1, FGF-23 and urine FABP-1 are not manifested in majority whereas serum NGAL, urine β2MG and RBP-4 in both matrices are detected above the max-DC in all cases, and we may further dilute the samples to get within the range.