Retinol-binding protein 4 (RBP4) is a 21 KDa protein mainly synthesized by hepatic cells, and its serum levels decreased significantly under the condition of liver injury or malnutrition.  Since RBP4 is mainly absorbed and degraded by the proximal renal tubular epithelial cells, urine RBP4 is currently the most sensitive functional biomarker of proximal tubule. Its serum and urine levels increased 50- to 100-fold in several renal disorders. The normal range of RBP4 is 17- 61 mg/L in serum, and is 0-1.4 mg/L in urine respectively. Lower serum levels of RBP4 are suggestive of chronic liver disease, cirrhosis or Vitamin A deficiency, whereas urine concentration of RBP4 higher than the upper limit is indicative of renal Fanconi syndrome.

RBP4 PETIA kit developed by IMD can accurately measure RBP4 concentrations in serum, plasma and urine samples

This assay is a turbidimetric immunoassay for the quantitative measurement of RBP4 in human serum and urine.  A standard or sample is added into a cuvette and mixed with the reaction buffer R1. After a short incubation, the test reagent R2, which is a suspension of microparticles coated with RBP4 antibodies, is added into the cuvette and mixed. The presence of RBP4 in the standard or sample causes the immune-particles to aggregate. The extent to which the microparticles aggregate is quantified by the amount of light scattering measured as absorbance by a chemistry analyzer. The concentration of RBP4 in unknown samples can be interpolated from a reference curve using the standards provided.

TYPICAL STANDARD CURVE

RBP4 (mg/L)	Absorbance (570 nm)
0	-0.0200
7.5	0.0263
15	0.0635
30	0.1429
75	0.3154
150	0.4208

 

Assay procedures may vary depending on the automated chemistry analyzer to be used. A general example of assay procedures is stated as follow:

1. Dispense 150µl of R1 into a clean cuvette

2. Add 1.5µl of sample and incubate at 37˚C for 5 minutes

3. Further add 50µl of R2

4. Read change of absorbance at 570 nm for 5 - 8 minutes after the addition of R2

5. Calculate the concentration of RBP4 in unknown sample by interpolation from a reference curve using the standards provided

Cat. No.	Size	Approximately tests
51060-05	R1: 15ml, R2: 5ml	100
51060-10	R1: 30ml, R2: 10ml	200
51060-20	R1: 60ml, R2: 20ml	400
51060-50	R1: 150ml, R2: 50ml	1000
51060-100	R1: 300ml, R2: 100ml	2000

For bulk order, please enquire

Product	Catalog           Number	Format	Method
Calibrator	51060-S1	5 x 1ml
Control	51060-C1	2 x 1ml