Factors that Interfere with HbA1c Test Results

Updated 11/21/2024

Information for physicians and patients regarding HbS, HbC, HbE and HbD traits

More about hemoglobin variants and HbA1c can also be found at the NIDDK web site:
Sickle Cell Trait and Other Hemoglobinopathies and Diabetes: Important Information for Physicians
For People of African, Mediterranean, or Southeast Asian Heritage: Important Information about Diabetes Blood Tests

Factors that Interfere with HbA1c Measurement: Genetic variants (e.g. HbS trait, HbC trait), elevated fetal hemoglobin (HbF) and chemically modified derivatives of hemoglobin (e.g. carbamylated Hb in patients with renal failure) can affect the accuracy of HbA1c measurements. The effects vary depending on the specific Hb variant or derivative and the specific HbA1c method. Table 1 contains information for most of the commonly used current HbA1c methods for the four most common Hb variants, elevated HbF and carbamylated Hb. The criteria for interference varies depending on the data source. Interferences from less common Hb variants and derivatives are discussed in Bry, et al [1] and Little, et al [69]. All entries in Table 1 are based on published information. In addition, if a product insert indicates clearly that there is inference from a particular factor, then the interference is entered as “yes” and the product insert is cited. When selecting an assay method, laboratories should take into consideration characteristics of the patient population served, (e.g. high prevalence of hemoglobinopathies or renal failure).

Factors that affect interpretation of HbA1c Results: Any condition that shortens erythrocyte survival or decreases mean erythrocyte age (e.g., recovery from acute blood loss, hemolytic anemia) will falsely lower HbA1c test results regardless of the assay method used [2]. HbA1c results from patients with HbSS, HbCC, and HbSC must be interpreted with caution given the pathological processes, including anemia, increased red cell turnover, and transfusion requirements, that adversely impact HbA1c as a marker of long-term glycemic control. Alternative forms of testing such as glycated serum protein or glycated albumin should be considered for these patients.

Iron deficiency anemia, a major public health problem in developing countries, is associated with higher HbA1c and higher fructosamine [3]. Consistent with these observations, iron replacement therapy lowers both HbA1c and fructosamine concentrations in diabetic and non-diabetic individuals [3-5]. HbA1c , but not glycated albumin, is increased in late pregnancy in nondiabetic individuals owing to iron deficiency [6]. Insight into the mechanism was recently obtained by the observation that malondialdehyde, which is increased in patients with iron deficiency anemia [3], enhances the glycation of hemoglobin [7]. Alternative measures of glycemic assessment (e.g., glucose monitoring) must be used in the presence of significant iron deficiency anemia, at least until the iron deficiency has been successfully treated.

Chronic renal failure develops in many diabetic patients. The role of glycemic control and the value of HbA1c in diabetic subjects with renal disease are controversial. While interference from carbamylated Hb can be evaluated, the role of renal anemia, erythropoietin intake, and other factors in chronic renal failure is more difficult to evaluate. Recent reports suggest HbA1c underestimates glycemic control in diabetic patients on dialysis and that glycated albumin is a more robust indicator of glycemic control [8-11]. Further studies are needed to clarify the role of HbA1c in diabetic patients with chronic renal failure.

Table 1: Effects of frequently encountered Hb variants and derivatives on HbA1c measurement

Method (listed in alphabetical order by manufacturer)	Interference (Yes/No)
Method (listed in alphabetical order by manufacturer)	*Hb C trait*	*Hb S trait*	*Hb E trait*	*Hb D trait*	Elevated HbF	*Carb Hb*
Abbott Architect c Enzymatic	No 59	No 59	No 59	No 59	-	-
Alere Nycocard	No 14	No 14	@	@	$	-
Alere Afinion	No 15	No 15	No 16	No 16	$	-
Arkray ADAMS A1c HA-8180V Variant Mode (Menarini) (*Denotes software version EU 1.41)	No 13,46,59	No 13,46,59	HbA1c not quantified 13, 46, 58 No*59 Yes 62	HbA1c not quantified 46, 58/ Yes 13 No*59	No <30% 46	-
Arkray ADAMS A1c HA-8180T (software version EU 1.41)	No 59	No 59	No 59	No 59	-	-
Arkray ADAMS A1c HA-8190V Variant Mode	No 67	No 67	No 67	No 67	No 67	-
Arkray The Lab 001 (POC)	No 70	Yes 70	No 70	No 70	No <42% 70
Beckman HbA1c Advanced B93009 Online Application on DxC 700 AU	No 64, 68	No 64, 68	No 64, 68	No 64, 68	-	-
Beckman HbA1c Advanced B00389 Manual Application on DxC 700 AU	No 68	No 68	No 68	No 68	-	-
Beckman HbA1c on Unicel DxC	No 68	No 68	No 68	No 68	-	-
Bio-Rad D-100	No 59, 72	No 59, 72	No 59, 72	No 59, 72	No ≤20% 63, Yes >29.9% 72	-
Bio-Rad D-10 (short Program)	No 15	No 15	No 16	No 16	No <12.5% 55	No 47
Bio-Rad Variant II A1c (NU)	No 59	No 59	No 16,59	No 16,59	No <10% 20	No 47
Bio-Rad Variant II Turbo (270-2415/2417)	No 15	No 15	Yes 16	Yes 16	No <5% 20	No 47
Bio-Rad Variant II Turbo 2.0	No 13,21,59	No 13,21,59	No 13,21, 54, 59, 62 Yes 45, 53	No 13,21,59	No <25% 20	No 47-
Diazyme Direct Enzymatic HbA1c	No 15,23	No 15,23	No 16,23	No 16	-	No 47
JEOL BM Test HbA1c on JCA-BM 6010/C	No 51	No 51	No 51, 54	No 51	No <15% 57	-
Menarini HA-8160 (Diabetes Mode)	No 17	No 17	Yes 16	Yes 16, 52	-	No 47
Menarini HA-8160 (Thalassemia Mode)	-	-	No 16	HbA1c not quantifed 16	-	-
Mindray BS-600M	No 72	No 72	No 72	No 72	Yes >9.6% 72	-
Ortho-Clinical Vitros	No 15, 29, 68	No 15, 29, 68	No 16, 68	No 16, 68	Yes >5% 55	-
Pointe Scientific Hemoglobin A1c	No 15,29	No 15,29	No 16	No 16	$	-
Polymer Tech Systems A1cNow	Yes 17	Yes 17	No 16	No 16	$	-
Roche Cobas Integra Gen2	No 15,31,32	No 15,31,32	No 16	No 16	$	No 47
Roche Tina-quant II on Hitachi	No 1, 33,35	No 1, 33,35	No 1, 6,35, 62	No 16	$	No 1, 27, 28
Roche Cobas c501	No 72	No 72	No 72	No 72	Yes >9.1% 72	-
Roche Cobas c513	No 68	No 68	No 68	No 68	$	-
Roche b 101	Yes 68 No 70	No 68,70	Yes 68,70	No 68, 70	No<9.5% 70	-
Sebia Capillarys 2 Flex Piercing	No 13,59	No 13,59	No 13, 54,59, 62	No 13,59	No ≤15% 48, <23% 65	No 48,49, 50
Sebia Capillarys 3 Tera	No 13,59, 72	No 13,59, 72	No 13, 54, 59, 72	No 13,59, 72	No <23% 65 Yes >16.0% 72	No 66
Siemens Advia A1c (immunoassay)	No 22,36, 68	No 22,36	-	-	$	-
Siemens Advia A1c (enzymatic)	No 68	No 68	No 68	No 68	$	-
Siemens Atellica A1c	No 68	No 68	No 68	No 68	$	-
Siemens DCA 2000/DCA Vantage	No 1, 24,33,37, 68, 71	No 1, 24, 71 / Yes 68	No 1, 16,39,40, 71 / Yes 68	No 16, 68, 71	No <10% 41,43	No 27, 42, 47
Siemens Dimension	No 17, 68	No 17, 68	No 16, 68	No 16, 68	$	-
Tosoh G8 Standard Mode	Yes 72	Yes 72	Yes 72	Yes 72	Yes >7.6% 72	-
Tosoh G8 Variant Mode V5.24 and V5.28	No 60, 61, 68	No 60, 61, 68	No 60, 68	No 60, 61, 68	No ≤30% 20, 55	No 47
Tosoh GX V1.24	No 68	No 68	No 68	No 68	-	-
Tosoh G11 Variant Mode V3.07	No 71	No 71	No 71	No 71	-	-
Trinity (Primus) Boronate Affinity HPLC	No 1, 15, 17, 33, 72	No 1, 15, 17, 33, 72	No 1, 16, 39, 62, 72	No 16, 72	No <15% 20,41, 43 Yes >10.6% 72	No 1, 27, 42,44

@ In the absence of specific method data, it can generally be assumed that immunoassay methods do not have clinically significant interference from HbE and HbD because the E and D substitution are distant from the N-terminus of the hemoglobin beta chain (16).

$ In the absence of specific method data, it can generally be assumed that immunoassay, boronate affinity and enzymatic methods show interference from elevated HbF levels (20, 43).

# When HbE trait is detected there is no significant interference. In cases where the presence of HbE trait is not detected, HbA1c results are artificially lowered.

- Not yet evaluated

Yes/No indicates that there is conflicting data in the literature. The indicator in bold is the opinion of the NGSP based on review of the literature cited.

NOTE:

Many other publications have been reviewed. Only those with conclusions that are reasonably supported by data are included.
For ion-exchange HPLC methods, interference from Hb variants and adducts may be dependent on the lot of reagents used (33).

References:

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