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| تحليل السي بيبتايد - C Peptide Test |
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| C Peptide |
♦ تحليل السي بيبتايد : هو عبارة عن تحليل يحدد كمية السي بيبتايد في الدم.
البنكرياس يفرز كلاً من: هرمون الإنسولين والسي بيبتايد, بكميات متساوية ,من خلال هذا التحليل يمكن معرفة كمية الإنسولين المُفرزة من الجسم لأن السي بيبتايد يتميز ببقاءه مدة أطول في الدم.
♦ يَستخدم الطبيب هذا التحليل لــ :
التفرقة بين النوع الأول والثاني من داء السكري. فعندما يُشخص المريض بالسكري، يتم عمل هذا التحليل لتحديد كمية الإنسولين المُفرزة من البنكرياس. فإذا وُجد السي بيبتايد، يُشخص المريض أنه مصاب بالنوع الثاني من السكري وإذا لم يُوجد، يُشخص بالنوع الأول.
♦ فهم نتائج هذا التحليل:
- In Some place the rage at 0.5-2.0 nanograms
- Others place the range at 0.8 -3.1 nomograms or 0.26-1.03 nomograms
- The range of results depends on why your doctor has ordered the test
- إن المعدل الطبيعي لتحليل السي بيبتايد هو بين 0.5 - 2.0 نانوجرام ⁄ مل.
- بالنسبة لمرضى السكري، فإنه يتم عمل تحليل السكر لتحديد نسبة السكر في الدم وكذلك في نفس الوقت تحليل السي بيبتايد لمعرفة كمية الإنسولين المُفرزة من الجسم.
- c peptide ينتج بصوره مساويه لإنتاج الانسولين الطبيعي من البنكرياس ولا يتأثر إنتاجه بأي انسولين خارجي مهما كانت كميته لذلك سكري النوع الأول المعتمد علي الانسولين لا يوقف أبدا جرعات الانسولين الخارجي بنوعيها القاعدي أو السريع
- لكن يتوقف أي أقراص معالجه للسكر ،لأن لو في بعض من انتاجيه الانسولين طبيعيا ،يمكن لهذه الأقراص التدخل في كميه الانسولين المنتجه طبيعيا
• معدل طبيعي + ارتفاع سكر الدم = النوع الثاني من السكري ..توجد كمية كافية من الإنسولين لكن الخلايا غير قادرة على التفاعل معه بشكل مناسب = ما يسمى بمقاومة الإنسولين
• انعدام /انخفاض السى بيبتايد في الدم + ارتفاع السكر = سكري نوع أول
• ارتفاع معدل السى بيبتايد + ارتفاع سكر الدم = سكري نوع ثاني وإنتاج الانسولين الزائد نتيجه وجود مقاومه لعمل الأنسولين
• ارتفاع معدل السى بيبتايد + انخفاض سكر الدم = وجود ورم في البنكرياس insulinoma
أوإذا لم يتوقف إستخدم ادويه المخفض للسكر في الدم من عائله sulfonylureas أو غيرها التي تحفز البنكرياس علي إنتاج الانسولين
السي ببتايد بيتعمل صايم مع سكر صايم لتقييم افراز الانسولين القاعدى .. وبيتعمل فاطر مع سكر فاطر لتقييم افراز الانسولين السريع الخاص بالوجبات ..
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Measuring C-peptide can help to determine how much of YOUR own natural insulin , any person who is producing insulin naturally has C-peptide secreted in equimolar amounts to insulin.
C-peptide levels are measured instead of insulin levels because C-peptide can assess a person's own insulin secretion even if they receive insulin injections.
C-peptide test measures the level of this peptide in the blood. It is generally found in amounts equal to insulin because insulin and C-peptide are linked when first made by the pancreas. Insulin helps the body use and control the amount of sugar (glucose) in the blood. Insulin allows glucose to enter body cells where it is used for energy. The level of C-peptide in the blood can show how much insulin is being made by the pancreas . C-peptide does not affect the blood sugar level in the body.
A C-peptide test can be done when diabetes has just been found and it is not clear whether type 1 diabetes or type 2 diabetes is present. A person whose pancreas does not make any insulin (type 1 diabetes) has a low level of insulin and C-peptide. A person with type 2 diabetes can have a normal or high level of C-peptide.
A C-peptide test can also help find the cause of low blood sugar (hypoglycemia), such as excessive use of medicine to treat diabetes or a noncancerous growth (tumor) in the pancreas (insulinoma). Because man-made (synthetic) insulin does not have C-peptide, a person with a low blood sugar level from taking too much insulin will have a low C-peptide level but a high level of insulin. An insulinoma causes the pancreas to release too much insulin, which causes blood sugar levels to drop (hypoglycemia). A person with an insulinoma will have a high level of C-peptide in the blood when they have a high level of insulin.
Why It Is Done
A C-peptide test is done to:
Help tell the difference between type 1 diabetes and type 2 diabetes.
Find the cause of low blood sugar (hypoglycemia).
Check to see whether a tumor of the pancreas (insulinoma) was completely removed.
How To Prepare
You may be asked to stop eating and drinking for 8 hours before having this blood test.
Insulin and some oral medicines used to treat type 2 diabetes can change the test results. Your doctor may ask you to stop these medicines before your blood test.
Talk to your doctor about any concerns you have regarding the need for the test, its risks, how it will be done, or what the results will mean.
How It Is Done
The health professional drawing your blood will:
Wrap an elastic band around your upper arm to stop the flow of blood. This makes the veins below the band larger so it is easier to put a needle into the vein.
Clean the needle site with alcohol.
Put the needle into the vein. More than one needle stick may be needed.
Attach a tube to the needle to fill it with blood.
Remove the band from your arm when enough blood is collected.
Put a gauze pad or cotton ball over the needle site as the needle is removed.
Put pressure on the site and then put on a bandage.
How It Feels
The blood sample is taken from a vein in your arm. An elastic band is wrapped around your upper arm. It may feel tight. You may feel nothing at all from the needle, or you may feel a quick sting or pinch.
Risks
There is very little chance of a problem from having a blood sample taken from a vein.
You may get a small bruise at the site. You can lower the chance of bruising by keeping pressure on the site for several minutes.
In rare cases, the vein may become swollen after the blood sample is taken. This problem is called phlebitis. A warm compress can be used several times a day to treat this.
Ongoing bleeding can be a problem for people with bleeding disorders. Aspirin, warfarin (Coumadin), and other blood-thinning medicines can make bleeding more likely. If you have bleeding or clotting problems, or if you take blood-thinning medicine, tell your doctor before your blood sample is taken.
Results
A C-peptide test measures the level of this peptide in the body.
Normal
The normal values listed here-called a reference range-are just a guide. These ranges vary from lab to lab, and your lab may have a different range for what's normal. Your lab report should contain the range your lab uses. Also, your doctor will evaluate your results based on your health and other factors. This means that a value that falls outside the normal values listed here may still be normal for you or your lab.
The level of C-peptide in the blood must be read with the results of a blood glucose test. Both these tests will be done at the same time. A test to measure insulin level also may be done.
C-peptide 1
Fasting:
0.51-2.72 nanograms per milliliter (ng/mL) or 0.17-0.90 nanomoles per liter (nmol/L)
High values
High levels of both C-peptide and blood glucose are found in people with type 2 diabetes or insulin resistance (such as from Cushing's syndrome).
A high level of C-peptide with a low blood glucose level may mean that an insulin-producing tumor of the pancreas (insulinoma) is present or that the use of certain medicines such as sulfonylureas (for example, glyburide) is causing the high level.
If C-peptide levels are high after an insulinoma is taken out, it may mean that the tumor has returned or that the tumor has spread to other parts of the body (metastasized).
Low values
Low levels of both C-peptide and blood glucose are found in liver disease, a severe infection, Addison's disease, or insulin therapy.
A low level of C-peptide with a high blood glucose level is found in people with type 1 diabetes.
Complete removal of the pancreas (pancreatectomy) causes a C-peptide level so low it can't be measured. The blood glucose level will be high, and insulin will be needed in order for the person to survive.
What Affects the Test
Reasons you may not be able to have the test or why the results may not be helpful include:
Taking medicines, such as insulin, or sulfonylurea medicines for type 2 diabetes.
Having kidney failure. Both insulin and C-peptide are removed from the body by the kidneys. C-peptide levels may be high in a person with kidney failure.
Being obese. More insulin is made in obese people and can cause high levels of C-peptide.
What To Think About
A C-peptide test must be done at the same time as a blood glucose test. To learn more, see the topic Blood Glucose.
A person with new type 2 diabetes often has a normal or high level of C-peptide in the blood. Over time, a person with type 2 diabetes may develop a low level of C-peptide.
To help tell the difference between type 1 and type 2 diabetes and to help guide treatment, most doctors look at a person's age, weight, and how long symptoms have been present. In rare cases, a C-peptide stimulation test may be done to help tell the difference between the two types of diabetes. During a C-peptide stimulation test, a blood sample is taken to measure C-peptide. Then a shot of a hormone to increase blood sugar (glucagon) is given into a vein in the arm. Another blood sample is taken. In people with type 1 diabetes, C-peptide levels will be low because the pancreas cannot make any insulin in response to the glucagon. In people with type 2 diabetes, C-peptide levels will be higher than the first blood test because the pancreas is making more insulin in response to the glucagon.
References
Citations
Fischbach FT, Dunning MB III, eds. (2009). Manual of Laboratory and Diagnostic Tests, 8th ed. Philadelphia: Lippincott Williams and Wilkins.
Other Works Consulted
Chernecky CC, Berger BJ (2008). Laboratory Tests and Diagnostic Procedures, 5th ed. St. Louis: Saunders.
Fischbach FT, Dunning MB III, eds. (2009). Manual of Laboratory and Diagnostic Tests, 8th ed. Philadelphia: Lippincott Williams and Wilkins.
Pagana KD, Pagana TJ (2010). Mosby’s Manual of Diagnostic and Laboratory Tests, 4th ed. St. Louis: Mosby Elsevier.
Credits
ByHealthwise Staff
Primary Medical ReviewerE. Gregory Thompson, MD - Internal Medicine
Specialist Medical ReviewerAlan C. Dalkin, MD - Endocrinology
Current as ofNovember 20, 2015
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