The analytical determination of the protein albumin in urine is important because increased values indicate an increased risk of developing end-stage renal diseases and cardiovascular disease among people with diabetes. Also albumin in urine is a sensitive indicator of renal damage caused by exposure to nephrotoxic substances. The most significant and well-documented of these abnormalities is a subtle increase in the urinary albumin excretion rate, known as mico-albuminuria. Mico-albuminuria is not measurable by conventional techniques for detecting proteinuria. It is believed that mico-albuminuria represents a reversible stage of renal dysfunction, whereas overt proteinuria reflects irreversible disease. Proteinuria typically appears about twenty years after the onset of diabetes, whereas mico-albuminuria can be detected within the first ten years. Mico-albuminuria (30-150ug/min) has been established as a marker predictive of subsequent development of diabetic nephropathy. Periodic monitoring(2-3 times/year) of urinary of albumin levels in the diabetic patient is therefore recommended so that the initial escalation of renal damage can be detected and appropriate treatment regimens can be instituted. Radial immunodiffusion, immunoturbidimetric, immunophelometric method and RIA have been used for the albumin assay in urine. This Micro- albumin Quantitative using microwell competitive ELISA method provides a convenient, sensitive and specific assay for albumin and free of interference from urine specimens.
Sample Type
Urine samples with albumin concentrations greater than 100ug/ml should be diluted with the zero standard (standard A) or normal saline and the results obtained should be multiplied by the appropriate dilution factor.
This kit has been used to measure albumin in mice transplanted with human tumors and in media from cultured cells (see references below).
Intended Use
This albumin ELISA kit is intended for the measurement of albumin in urine samples only. It cannot be used to measure albumin in serum or plasma. Furthermore, it is recommended that the urine samples should not be frozen before the assay.
Sensitivity
Based on sixteen replicates determinations of the zero standard, the minimum albumin concentration detectable using this assay is 1ug/ml. The detection limit is defined as the value deviating by 2 SD from the zero standard.
Range
Five different patient urine samples (with original albumin concentrations of 50, 77.6, 103, 176, and 327mg/l) were diluted (1:2, 1:5, and 1:10) with the zero standard and their final albumin values determined. The samples showed excellent mean recoveries of about 94% (range 85-109%).
Test Principle
Albumin ELISA kit is based on competitive binding of human albumin from urine samples and albumin coated on the microwell plate to the enzyme labeled anti- human albumin antibody. Higher concentrations of albumin in the urine samples result in decreased binding of enzyme (HRP) labeled antibody to the microwell plate. After a washing step, chromogenic substrate is added and color developed. The enzymatic reaction (color) is inversely proportional to the amount of albumin present in the sample. Adding stopping solution terminates the reaction. Absorbance is then measured on a microtiter well ELISA reader at 450nm. and the concentration of albumin in samples and control is read off the standard curve.
Kit Components
Human Albumin coated microwell strip plate: 1 X 96 wells Albumin Std. A: 1 X 11ml Albumin Std. B (2.5ug/ml): 1 X 0.5ml Albumin Std. C (5ug/ml): 1 X 0.5ml Albumin Std. D (25ug/ml): 1 X 0.5ml Albumin Std. E (50ug/ml): 1 X 0.5ml Albumin Std. F (100ug/ml): 1 X 0.5ml Albumin Control (exact value printed on the vial) Anti-Albumin-HRP Conjugate: 1 X 11ml HRP substrate Solution: 1 X 11ml Wash buffer (100X): 1 X 10ml, dilute 1:100 with distilled water Stop solution (ready-to-use): 1 X 10ml
Storage and Stability
Store liquid at -20°C. Store other components at 4°C. Stable for 6 months. For maximum recovery of product, centrifuge the original vial prior to removing the cap.
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