DESCRIPTION

Chromogranin A is a member of the granin family of neuroendocrine secretory proteins. It is located in secretory vesicles of neurons and endocrine cells. Chromogranin A is the precursor to several functional peptides including vasostatin, pancreastatin, catestatin and parastatin. These peptides negatively modulate the neuroendocrine function of the releasing cell (autocrine) or nearby cells (paracrine). CgA is one of the most used tumor markers in NET's (neuroendocrine tumors), and elevated CgA concentrations have been demonstrated in serum or plasma of patients with different types of these tumors. However, CgA is not a tumor-specific antigen for NETs, and an abnormal concentration has been described in some non-malignant diseases such as renal failure, heart failure, proton pump inhibition, gastritis, hypertension, or patients with liver diseases.

PRINCIPLE OF THE ASSAY

A capture antibody is pre-coated onto the bottom of wells which binds to analyte of interest. A detection antibody also binds to the analyte. Horseradish peroxidase (HRP)-conjugated secondary antibody binds to the detection antibody. TMB acts as the HRP substrate and the solution color will change from colorless to blue. A stop solution containing sulfuric acid turns solution yellow. The color intensity is proportional to the quantity of bound protein which is measurable at 450 nm with the correction wavelength set at 630 nm.

PRECISION

Intra-assay Precision (Precision within an assay) Three samples of known concentration were tested 20 times on one plate to assess intra-assay precision. Inter-assay Precision (Precision between assays) Three samples of known concentration were tested in 24 separate assays to assess inter-assay precision.

Intra-assay Precision

Sample	n	Mean (pg/mL)	SD	CV%
1	20	4,347.9	373.3	8.6
2	20	1,515.1	63.7	4.3
3	20	338.5	9.5	2.8

Inter-assay Precision

Sample	n	Mean (pg/mL)	SD	CV%
1	24	5,060.1	474.0	9.4
2	24	1,533.1	116.1	7.6
3	24	330.0	15.9	4.8

RECOVERY

The recovery of human CHGA spiked to three different levels throughout the range of the assay in human plasma averaged 96%, ranging from 83%-114%.

LINEARITY

To assess the linearity of the assay, human plasma samples were diluted with the appropriate Sample Diluent to produce samples with values within the dynamic range of the assay.

		Human plasma
1:4	Average% of Expected	100
	Range (%)	99-101
1:8	Average% of Expected	92
	Range (%)	83-97
1:16	Average% of Expected	89
	Range (%)	83-96
1:32	Average% of Expected	90
	Range (%)	84-94

CALIBRATION

This immunoassay is calibrated against a highly purified recombinant human CHGA produced at Sunlong Medical™.

Ordering & shipping

• Minimum order: 1 kit
• Lead time: varies with order quantity and specifications. Please consult your local distributor or our sales team for confirmation
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• Shipping: FedEx / DHL / UPS express; cold-chain packing available on request
• Price: USD, per kit (48T / 96T options available)