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# A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
HbA1C
Test Code: GH
Synonyms/Keywords
Hgb A1C, Glycosylated Hemoglobin (GH), A1C, eAG, Hemoglobin A1C​
Test Components
Hemoglobin A1C, eAG​
Useful For
​Diagnosing diabetes and evaluation of long-term blood glucose concentration in diabetic patients.
Specimen Requirements
Fasting Required Specimen Type Preferred Container/Tube Acceptable Container/Tube Specimen Volume Specimen Minimum Volume
(allows for 1 repeat)
Pediatric Minimum Volume
(no repeat)
No​ Whole Blood​ EDTA Lavender Top Tube (LTT)​ Sodium-heparin Green Top Tube (GTT)​ 1.0 mL​ 0.2 mL​ 0.2 mL​
Collection Processing Instructions
Collection kits for patients to collect specimens at home can be made available prior to appointment.  Contact Marshfield Labs for more information.  ​
Specimen Stability Information
Specimen Type Temperature Time
Whole Blood​ Ambient 24 hours
Refrigerate 7 days
​Frozen at -20 deg Celsius ​1 month
​Frozen at -70 deg Celsius ​1 year
Avoid repeated freeze and thaw cycles.​ ​ ​
Performing Laboratory Information
Performing Location Day(s) Test Performed Analytical Time Methodology/Instrumentation
Marshfield​ Monday through Friday​ Less than 2 hours​

Ion Exchange HPLC/G8 TOSOH.
Method is traceable to DCCT.​

Test Information
Results include %HbA1c and estimated average glucose (eAG).
If abnormal hemoglobin is present, hemoglobin electrophoresis can be ordered; will be performed at Mayo Medical Laboratories.
Reference Range Information
Performing Location Reference Range
Marshfield​
 >=18 yrs: 4.0-6.0%
 
Recent recommendations by American Diabetes Association (ADA)
 
Criteria for diagnosising Diabetes: HbA1C >=6.5%
HBA1c levels of 5.7-6.4% indicate an increased risk for developing diabetes.
 
Therapeutic goals for glycemic control:
Adults (non-pregnant): <7%; less stringent goal <8% for patients with a history of severe hypoglycemia, limited life expectancy, advanced microvascular or macrovascular complications.
 
Reference values have not been established for patients <18 yrs of age. 
Results include %HbA1c and estimated average glucose (eAG). 
eAG mg/dL=(28.7 x HbA1c)-46.7.
Interpretation

When diagnosing diabetes, an elevated level should be confirmed with repeat testing, except in symptomatic patients and who have plasma glucose >200 mg/dl. American Diabetes Association (ADA) recommends HbA1c should be measured 3-4 times per year for type 1 and poorly controlled type 2 diabetes and 2 times per year for well-controlled type 2 diabetic patients.

HbA1c assay reflects long-term fluctuations in blood glucose concentration, a diabetic patient who may have come in recent weeks under good control may still have a high concentration of HbA1c and conversely a diabetic patient previously under good control now poorly controlled may still have low concentrations of HbA1c.

In conditions with shortened erythrocyte lifespan (hemolytic anemia), HbA1c results will be decreased and affect will be dependent on the severity of anemia. Patients with polycythemia or post-splenectomy may exhibit increased HbA1c levels due to longer erythrocyte lifespan. HbA1c values in recently transfused patients may be falsely elevated.

HPLC HbA1c method does not shows any interference for hemoglobin variants, heterozygous HbS, HbC and HbD and HbF <=25%( Elevated HbF can be identified in HPLC methods but not in immunoassays). HbE shows interference with HPLC method and falsely lowers the HbA1c. Other variants may also show interference. In patients with homozygous forms of variant Hb (e.g. SS, CC, EE) SC), there is no HbA thus no HbA1c values cannot be quantitated using this method. In such situations fructosamine should be used as an alternate method for monitoring glycemic control.

Outreach CPTs
CPT Modifier
(if needed)
Quantity Description Comments
83036​
Synonyms/Keywords
Hgb A1C, Glycosylated Hemoglobin (GH), A1C, eAG, Hemoglobin A1C​
Test Components
Hemoglobin A1C, eAG​
Ordering Applications
Ordering Application Description
​Centricity ​Hemoglobin A1C
​Cerner ​Hemoglobin A1c
If the ordering application you are looking for is not listed, contact your local laboratory for assistance.
Specimen Requirements
Fasting Required Specimen Type Preferred Container/Tube Acceptable Container/Tube Specimen Volume Specimen Minimum Volume
(allows for 1 repeat)
Pediatric Minimum Volume
(no repeat)
No​ Whole Blood​ EDTA Lavender Top Tube (LTT)​ Sodium-heparin Green Top Tube (GTT)​ 1.0 mL​ 0.2 mL​ 0.2 mL​
Collection Processing Instructions
Collection kits for patients to collect specimens at home can be made available prior to appointment.  Contact Marshfield Labs for more information.  ​
Specimen Stability Information
Specimen Type Temperature Time
Whole Blood​ Ambient 24 hours
Refrigerate 7 days
​Frozen at -20 deg Celsius ​1 month
​Frozen at -70 deg Celsius ​1 year
Avoid repeated freeze and thaw cycles.​ ​ ​
Useful For
​Diagnosing diabetes and evaluation of long-term blood glucose concentration in diabetic patients.
Test Information
Results include %HbA1c and estimated average glucose (eAG).
If abnormal hemoglobin is present, hemoglobin electrophoresis can be ordered; will be performed at Mayo Medical Laboratories.
Reference Range Information
Performing Location Reference Range
Marshfield​
 >=18 yrs: 4.0-6.0%
 
Recent recommendations by American Diabetes Association (ADA)
 
Criteria for diagnosising Diabetes: HbA1C >=6.5%
HBA1c levels of 5.7-6.4% indicate an increased risk for developing diabetes.
 
Therapeutic goals for glycemic control:
Adults (non-pregnant): <7%; less stringent goal <8% for patients with a history of severe hypoglycemia, limited life expectancy, advanced microvascular or macrovascular complications.
 
Reference values have not been established for patients <18 yrs of age. 
Results include %HbA1c and estimated average glucose (eAG). 
eAG mg/dL=(28.7 x HbA1c)-46.7.
Interpretation

When diagnosing diabetes, an elevated level should be confirmed with repeat testing, except in symptomatic patients and who have plasma glucose >200 mg/dl. American Diabetes Association (ADA) recommends HbA1c should be measured 3-4 times per year for type 1 and poorly controlled type 2 diabetes and 2 times per year for well-controlled type 2 diabetic patients.

HbA1c assay reflects long-term fluctuations in blood glucose concentration, a diabetic patient who may have come in recent weeks under good control may still have a high concentration of HbA1c and conversely a diabetic patient previously under good control now poorly controlled may still have low concentrations of HbA1c.

In conditions with shortened erythrocyte lifespan (hemolytic anemia), HbA1c results will be decreased and affect will be dependent on the severity of anemia. Patients with polycythemia or post-splenectomy may exhibit increased HbA1c levels due to longer erythrocyte lifespan. HbA1c values in recently transfused patients may be falsely elevated.

HPLC HbA1c method does not shows any interference for hemoglobin variants, heterozygous HbS, HbC and HbD and HbF <=25%( Elevated HbF can be identified in HPLC methods but not in immunoassays). HbE shows interference with HPLC method and falsely lowers the HbA1c. Other variants may also show interference. In patients with homozygous forms of variant Hb (e.g. SS, CC, EE) SC), there is no HbA thus no HbA1c values cannot be quantitated using this method. In such situations fructosamine should be used as an alternate method for monitoring glycemic control.

For more information visit:
Performing Laboratory Information
Performing Location Day(s) Test Performed Analytical Time Methodology/Instrumentation
Marshfield​ Monday through Friday​ Less than 2 hours​

Ion Exchange HPLC/G8 TOSOH.
Method is traceable to DCCT.​

For billing questions, see Contacts
Outreach CPTs
CPT Modifier
(if needed)
Quantity Description Comments
83036​
For most current information refer to the Marshfield Laboratory online reference manual.