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Test Code (รหัสการทดสอบ):
090-31-3007-01

Order Name (ชื่อการทดสอบ):
C-Peptide **

 
Specimen / Container (สิ่งส่งตรวจ/ภาชนะ):
Blood/ Plain blood (Red top) 5 mL, 1 tube
 
Turnaround Time (ระยะเวลารอผล):
Received specimen to reported within 2 days
(Exception for official holidays)
 
Useful For (ประโยชน์การทดสอบ):

Diagnostic workup of hypoglycemia:
-Diagnosis of factitious hypoglycemia due to surreptitious administration of insulin
-Evaluation of possible insulinoma
-Surrogate measure for the absence or presence of physiological suppressibility of endogenous insulin secretion during diagnostic insulin-induced hypoglycemia (C-peptide suppression test).
Assessing insulin secretory reserve in selected diabetic patients (as listed below) who either have insulin autoantibodies or who are receiving insulin therapy:
-Assessing residual endogenous insulin secretory reserve
-Monitoring pancreatic and islet cell transplant function
-Monitoring immunomodulatory therapy aimed at slowing progression of preclinical, or very early stage type 1 diabetes mellitus

 
Methodology (วิธีการทดสอบ):
Electrochemiluminescence Immunoassay (ECLIA)
 
Test List In Profile (การทดสอบใน Profile):
Change performing place from BRIA to RAMA // SJ 8 Mar 2022
 
AliasesName (ชื่อเรียกอื่นๆ) :
C Peptide Connecting Peptide of Insulin
C Peptide
Connecting Peptide of Insulin
 
 
 
Test Code (รหัสการทดสอบ):
090-31-3007-01

Order Name (ชื่อการทดสอบ):
C-Peptide **

 
Patient Preparation (การเตรียมตัวผู้ป่วย):
Patient should fasting for 8-12 hours.
 
Collection Specimen Or Container (สิ่งส่งตรวจ/ภาชนะ):
Blood/ Plain blood (Red top) 5 mL, 1 tube
 
Specimen Testing Type (สิ่งส่งตรวจที่ใช้ในการทดสอบ):
Serum, minimum volume 2 mL
 
Sub Mission Container (ภาชนะส่งตรวจ):
Plastic tube
 
 
 
Test Code (รหัสการทดสอบ):
090-31-3007-01

Order Name (ชื่อการทดสอบ):
C-Peptide **

 
Method detail (วิธีการทดสอบ):
Chemiluminescence
 
Schedule (ตารางการทดสอบ):
N/A **Send out to Clinical Chemistry, Ramathibodi
 
Turnaround Time (ระยะเวลารอผล):
Received specimen to reported within 2 days
(Exception for official holidays)
 
Performing Location (หน่วยงานที่ทำการทดสอบ):
Clinical Chemistry, Ramathibodi
Referral Lab Services, Laboratory Department 14160-2
 
 
 
Test Code (รหัสการทดสอบ):
090-31-3007-01

Order Name (ชื่อการทดสอบ):
C-Peptide **

 
 
Clinical Information (ข้อมูลทางคลินิก):

C-peptide (connecting peptide), a 31-amino-acid polypeptide, represents the midportion of the proinsulin molecule. Proinsulin resembles a hairpin structure, with an N-terminal and C-terminal, which correspond to the A and B chains of the mature insulin molecule, oriented parallel to each other and linked by disulfide bonds. The looped portion of the hairpin between the A and B chains is called C-peptide. During insulin secretion, C-peptide is enzymatically cleaved off and cosecreted in equimolar proportion with mature insulin molecules.
Following secretion, insulin and C-peptide enter the portal circulation and are routed through the liver where at least 50% of the insulin binds to receptors, initiates specific hepatic actions (stimulation of hepatic glucose uptake and suppression of glycogenolysis, gluconeogenesis, and ketogenesis), and is subsequently degraded. Most of the insulin molecules that pass through the liver into the main circulation bind to peripheral insulin receptors, promoting glucose uptake, while the remaining molecules undergo renal elimination. Unlike insulin, C-peptide is subject to neither hepatic nor significant peripheral degradation but is mainly removed by the kidneys. As a result, C-peptide has a longer half-life than insulin (30-35 minutes versus 5-10 minutes), and the molar ratio of circulating insulin to circulating C-peptide is generally below 1, despite equimolar secretion. Until recently, C-peptide was thought to have no physiological function, but it now appears that there may be specific C-peptide cell-surface receptors (most likely belonging to the super-family of G-protein coupled receptors), which influence endothelial responsiveness and skeletal and renal blood flow.
In most disease conditions associated with abnormal serum insulin levels, the changes in serum C-peptide levels parallel insulin-related alterations (insulin to C-peptide molar ratio < or =1). Both serum C-peptide and serum insulin levels are elevated in renal failure and in disease states that lead to augmented primary endogenous insulin secretion (eg, insulinoma, sulfonylurea intoxication). Both also may be raised in any disease states that cause secondary increases in endogenous insulin secretion mediated through insulin resistance, primarily obesity, glucose intolerance, and early type 2 diabetes mellitus (DM), as well as endocrine disorders associated with hypersecretion of insulin-antagonistic hormones (eg, Cushing syndrome, acromegaly). Failing insulin secretion in type 1 DM and longstanding type 2 DM is associated with corresponding reductions in serum C-peptide levels.
Discordant serum insulin and serum C-peptide abnormalities are mainly observed in 2 situations: exogenous insulin administration and the presence of anti-insulin autoantibodies. Factitious hypoglycemia due to surreptitious insulin administration results in appropriate suppression of endogenous insulin and C-peptide secretion. At the same time, the peripherally administered insulin bypasses the hepatic first-pass metabolism. In these situations, insulin levels are elevated and C-peptide levels are decreased. In patients with insulin antibodies, insulin levels are increased because of the prolonged half-life of autoantibody-bound insulin. Some patients with anti-idiotypic anti-insulin autoantibodies experience episodic hypoglycemia caused by displacement of autoantibody-bound insulin.

 
Reference Value (ค่าอ้างอิง):
1.1 - 4.4 ng/mL