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22525 Hemoglobin A1C

Hemoglobin A1C
Test Code: GH
Synonyms/Keywords
​Hgb A1C, Glycosylated Hemoglobin (GH), A1C, eAG, HbA1C, Glycemic Index
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)​1.0 mL​0.3 mL​0.2 mL​
Collection Processing Instructions

​Send specimen in original tube; DO NOT ALIQUOT.

Specimen Stability Information
Specimen Type Temperature Time
Whole Blood​ ​ ​ Ambient 18 hours
Refrigerate 7 days

​Frozen -80oC
(if frozen within the first 8 hours after collection)
​3 months
Performing Laboratory Information
Performing Location Day(s) Test Performed Analytical Time Methodology/Instrumentation
Chippewa Falls​ ​Monday through Friday​ ​Less than 2 hours ​Turbidimetric Inhibition Immunoassay/Siemens Dimension
​Diagnostic Treatment Center ​Monday through Sunday ​Less than 2 hours ​​Turbidimetric Inhibition Immunoassay/Siemens Dimension
​Eau Claire ​Monday through Sunday ​Less than 2 hours ​​Turbidimetric Inhibition Immunoassay/Siemens Dimension
​Flambeau Hospital ​Monday through Sunday ​Less than 2 hours ​​Turbidimetric Inhibition Immunoassay/Siemens Dimension
​Ladysmith Medical Center ​Monday through Sunday​ ​Less than 2 hours ​​Turbidimetric Inhibition Immunoassay/Siemens Dimension
​Lakeview Medical Center ​Monday through Sunday ​Less than 2 hours ​​Turbidimetric Inhibition Immunoassay/Siemens Dimension
Marshfield​ Monday through Friday​ Time: 0700-1400
(Samples received in the department after 1400 may be reported the following business day.)​
 Less than 2 hours​

Capillarys Electrophoresis, Sebia

​Merrill ​Monday through Friday​ ​Less than 2 hours ​​Turbidimetric Inhibition Immunoassay/Siemens Dimension
Minocqua​ ​Monday through Sunday ​Less than 2 hours ​​Turbidimetric Inhibition Immunoassay/Siemens Dimension
​Neillsville​Monday through Sunday​Less than 2 hours​Turbidimetric Inhibition Immunoassay/Siemens Dimension
Stevens Point​ ​Monday through Friday​ ​Less than 2 hours ​​Turbidimetric Inhibition Immunoassay/Siemens Dimension
​Wausau ​Monday through Sunday ​Less than 2 hours ​​Turbidimetric Inhibition Immunoassay/Siemens Dimension
​Wisconsin Rapids ​Monday through Friday​ ​Less than 2 hours ​​Turbidimetric Inhibition Immunoassay/Siemens Dimension
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
All Performing Sites
 >=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.  

Capillary electrophoresis HbA1c method does not shows any interference for hemoglobin variants, heterozygous HbS, HbC and HbD and HbF <=15%( Elevated HbF can be identified in capillary electrophoresis methods but not in immunoassays). Levels of Hb F up to 15% in the blood sample do not interfere with HbA1c quantification. Samples that contain high amounts of Hb F (>15%), usually found in some people with thalassemia, infants, and some pregnant women, may yield a lower than expected HbA1c result with this assay. 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.

Individuals with recent significant blood loss exhibit falsely low HbA1c values due to a higher fraction of young erythrocytes.

Abnormal life span of red blood cells as found in hemolytic anemia, polycythemia or post splenectomy may affect the levels of HbA1c.

Outreach CPTs
CPT Modifier
(if needed)		 Quantity Description Comments
83036​ ​ ​ ​ ​
Synonyms/Keywords
​Hgb A1C, Glycosylated Hemoglobin (GH), A1C, eAG, HbA1C, Glycemic Index
Test Components
Hemoglobin A1C, eAG​
Ordering Applications
Ordering Application Description
​Cerner ​Hemoglobin A1c
​COM ​HbA1c
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)​1.0 mL​0.3 mL​0.2 mL​
Collection Processing

​Send specimen in original tube; DO NOT ALIQUOT.

Specimen Stability Information
Specimen Type Temperature Time
Whole Blood​ ​ ​ Ambient 18 hours
Refrigerate 7 days

​Frozen -80oC
(if frozen within the first 8 hours after collection)
​3 months
Useful For
​Diagnosing diabetes and evaluation of long-term blood glucose concentration in diabetic patients.
Test Components
Hemoglobin A1C, eAG​
Reference Range Information
Performing Location Reference Range
All Performing Sites
 >=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.  

Capillary electrophoresis HbA1c method does not shows any interference for hemoglobin variants, heterozygous HbS, HbC and HbD and HbF <=15%( Elevated HbF can be identified in capillary electrophoresis methods but not in immunoassays). Levels of Hb F up to 15% in the blood sample do not interfere with HbA1c quantification. Samples that contain high amounts of Hb F (>15%), usually found in some people with thalassemia, infants, and some pregnant women, may yield a lower than expected HbA1c result with this assay. 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.

Individuals with recent significant blood loss exhibit falsely low HbA1c values due to a higher fraction of young erythrocytes.

Abnormal life span of red blood cells as found in hemolytic anemia, polycythemia or post splenectomy may affect the levels of HbA1c.

For more information visit:
Performing Laboratory Information
Performing Location Day(s) Test Performed Analytical Time Methodology/Instrumentation
Chippewa Falls​ ​Monday through Friday​ ​Less than 2 hours ​Turbidimetric Inhibition Immunoassay/Siemens Dimension
​Diagnostic Treatment Center ​Monday through Sunday ​Less than 2 hours ​​Turbidimetric Inhibition Immunoassay/Siemens Dimension
​Eau Claire ​Monday through Sunday ​Less than 2 hours ​​Turbidimetric Inhibition Immunoassay/Siemens Dimension
​Flambeau Hospital ​Monday through Sunday ​Less than 2 hours ​​Turbidimetric Inhibition Immunoassay/Siemens Dimension
​Ladysmith Medical Center ​Monday through Sunday​ ​Less than 2 hours ​​Turbidimetric Inhibition Immunoassay/Siemens Dimension
​Lakeview Medical Center ​Monday through Sunday ​Less than 2 hours ​​Turbidimetric Inhibition Immunoassay/Siemens Dimension
Marshfield​ Monday through Friday​ Time: 0700-1400
(Samples received in the department after 1400 may be reported the following business day.)​
 Less than 2 hours​

Capillarys Electrophoresis, Sebia

​Merrill ​Monday through Friday​ ​Less than 2 hours ​​Turbidimetric Inhibition Immunoassay/Siemens Dimension
Minocqua​ ​Monday through Sunday ​Less than 2 hours ​​Turbidimetric Inhibition Immunoassay/Siemens Dimension
​Neillsville​Monday through Sunday​Less than 2 hours​Turbidimetric Inhibition Immunoassay/Siemens Dimension
Stevens Point​ ​Monday through Friday​ ​Less than 2 hours ​​Turbidimetric Inhibition Immunoassay/Siemens Dimension
​Wausau ​Monday through Sunday ​Less than 2 hours ​​Turbidimetric Inhibition Immunoassay/Siemens Dimension
​Wisconsin Rapids ​Monday through Friday​ ​Less than 2 hours ​​Turbidimetric Inhibition Immunoassay/Siemens Dimension
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.