Hemoglobin Raleigh results in factitiously low hemoglobin A1c when evaluated via immunoassay analyzer

Nina Jain, Mehmet Kesimer, James Hoyer, Ali S. Calikoglu

Research output: Contribution to journalReview article

7 Citations (Scopus)

Abstract

Background: Glycosylated hemoglobin (HbA1c) is commonly used to assess long-term blood glucose control in patients with diabetes mellitus. Numerous conditions including hemoglobinopathies can alter HbA1c measurements and cause misleading results. Objective: To report a 13-year-old male with Type 1 diabetes mellitus who had low HbA1c measurements, despite persistent hyperglycemia. Design/Methods: HbA1c was initially measured by immunoassay. Hb electrophoresis was then employed to assess potential Hb variants. Electrospray ionization (ESI) tandem mass spectrometry of isolated Hb and gene sequencing of the Hbβ gene were used to specifically identify the Hb variant. Results: HbA1c measurement by immunoassay revealed an unusually low HbA1c of 3.9%. Hb electrophoresis revealed an aberrant Hb. The ESI mass spectrum of the intact Hb sample revealed a variant β-chain of 15,881 Da, 14 Da heavier than the mass of the normal Hb β-chain (15,867 Da). Sequence analysis of the 965.45 Da peptide suggested a substitution of valine (Val) to acetylated alanine (Ala). The DNA sequence of the patient's Hbβ gene revealed a single-base heterozygous mutation (GTG to GCG) at Base 2 of the codon of the first amino acid, producing a Val→Ala substitution, previously termed Hb-Raleigh. Because the acetylated N-terminal amino acid of the Hb-Raleigh β chain cannot be glycated, the HbA1c immunoassay will result in falsely low HbA1c levels. Conclusion: In managing diabetic patients, knowledge of hemoglobinopathies influencing HbA1c determination methods is essential because hemoglobin variants may cause mismanagement of diabetes. Unusual results should prompt further analysis for a hemoglobinopathy as the potential cause of aberrant results.

Original languageEnglish (US)
Pages (from-to)14-18
Number of pages5
JournalJournal of Diabetes and its Complications
Volume25
Issue number1
DOIs
StatePublished - Jan 1 2011

Fingerprint

Hemoglobinopathies
Immunoassay
Hemoglobins
Electrophoresis
Genes
Amino Acids
Electrospray Ionization Mass Spectrometry
Glycosylated Hemoglobin A
Valine
Tandem Mass Spectrometry
Type 1 Diabetes Mellitus
Codon
Hyperglycemia
Alanine
Sequence Analysis
Blood Glucose
Diabetes Mellitus
Peptides
Mutation
hemoglobin Raleigh

Keywords

  • Hb Raleigh
  • HbA1c
  • Hemoglobinopathy
  • Mass spectrometry

ASJC Scopus subject areas

  • Endocrinology
  • Endocrinology, Diabetes and Metabolism
  • Internal Medicine

Cite this

Hemoglobin Raleigh results in factitiously low hemoglobin A1c when evaluated via immunoassay analyzer. / Jain, Nina; Kesimer, Mehmet; Hoyer, James; Calikoglu, Ali S.

In: Journal of Diabetes and its Complications, Vol. 25, No. 1, 01.01.2011, p. 14-18.

Research output: Contribution to journalReview article

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abstract = "Background: Glycosylated hemoglobin (HbA1c) is commonly used to assess long-term blood glucose control in patients with diabetes mellitus. Numerous conditions including hemoglobinopathies can alter HbA1c measurements and cause misleading results. Objective: To report a 13-year-old male with Type 1 diabetes mellitus who had low HbA1c measurements, despite persistent hyperglycemia. Design/Methods: HbA1c was initially measured by immunoassay. Hb electrophoresis was then employed to assess potential Hb variants. Electrospray ionization (ESI) tandem mass spectrometry of isolated Hb and gene sequencing of the Hbβ gene were used to specifically identify the Hb variant. Results: HbA1c measurement by immunoassay revealed an unusually low HbA1c of 3.9{\%}. Hb electrophoresis revealed an aberrant Hb. The ESI mass spectrum of the intact Hb sample revealed a variant β-chain of 15,881 Da, 14 Da heavier than the mass of the normal Hb β-chain (15,867 Da). Sequence analysis of the 965.45 Da peptide suggested a substitution of valine (Val) to acetylated alanine (Ala). The DNA sequence of the patient's Hbβ gene revealed a single-base heterozygous mutation (GTG to GCG) at Base 2 of the codon of the first amino acid, producing a Val→Ala substitution, previously termed Hb-Raleigh. Because the acetylated N-terminal amino acid of the Hb-Raleigh β chain cannot be glycated, the HbA1c immunoassay will result in falsely low HbA1c levels. Conclusion: In managing diabetic patients, knowledge of hemoglobinopathies influencing HbA1c determination methods is essential because hemoglobin variants may cause mismanagement of diabetes. Unusual results should prompt further analysis for a hemoglobinopathy as the potential cause of aberrant results.",
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N2 - Background: Glycosylated hemoglobin (HbA1c) is commonly used to assess long-term blood glucose control in patients with diabetes mellitus. Numerous conditions including hemoglobinopathies can alter HbA1c measurements and cause misleading results. Objective: To report a 13-year-old male with Type 1 diabetes mellitus who had low HbA1c measurements, despite persistent hyperglycemia. Design/Methods: HbA1c was initially measured by immunoassay. Hb electrophoresis was then employed to assess potential Hb variants. Electrospray ionization (ESI) tandem mass spectrometry of isolated Hb and gene sequencing of the Hbβ gene were used to specifically identify the Hb variant. Results: HbA1c measurement by immunoassay revealed an unusually low HbA1c of 3.9%. Hb electrophoresis revealed an aberrant Hb. The ESI mass spectrum of the intact Hb sample revealed a variant β-chain of 15,881 Da, 14 Da heavier than the mass of the normal Hb β-chain (15,867 Da). Sequence analysis of the 965.45 Da peptide suggested a substitution of valine (Val) to acetylated alanine (Ala). The DNA sequence of the patient's Hbβ gene revealed a single-base heterozygous mutation (GTG to GCG) at Base 2 of the codon of the first amino acid, producing a Val→Ala substitution, previously termed Hb-Raleigh. Because the acetylated N-terminal amino acid of the Hb-Raleigh β chain cannot be glycated, the HbA1c immunoassay will result in falsely low HbA1c levels. Conclusion: In managing diabetic patients, knowledge of hemoglobinopathies influencing HbA1c determination methods is essential because hemoglobin variants may cause mismanagement of diabetes. Unusual results should prompt further analysis for a hemoglobinopathy as the potential cause of aberrant results.

AB - Background: Glycosylated hemoglobin (HbA1c) is commonly used to assess long-term blood glucose control in patients with diabetes mellitus. Numerous conditions including hemoglobinopathies can alter HbA1c measurements and cause misleading results. Objective: To report a 13-year-old male with Type 1 diabetes mellitus who had low HbA1c measurements, despite persistent hyperglycemia. Design/Methods: HbA1c was initially measured by immunoassay. Hb electrophoresis was then employed to assess potential Hb variants. Electrospray ionization (ESI) tandem mass spectrometry of isolated Hb and gene sequencing of the Hbβ gene were used to specifically identify the Hb variant. Results: HbA1c measurement by immunoassay revealed an unusually low HbA1c of 3.9%. Hb electrophoresis revealed an aberrant Hb. The ESI mass spectrum of the intact Hb sample revealed a variant β-chain of 15,881 Da, 14 Da heavier than the mass of the normal Hb β-chain (15,867 Da). Sequence analysis of the 965.45 Da peptide suggested a substitution of valine (Val) to acetylated alanine (Ala). The DNA sequence of the patient's Hbβ gene revealed a single-base heterozygous mutation (GTG to GCG) at Base 2 of the codon of the first amino acid, producing a Val→Ala substitution, previously termed Hb-Raleigh. Because the acetylated N-terminal amino acid of the Hb-Raleigh β chain cannot be glycated, the HbA1c immunoassay will result in falsely low HbA1c levels. Conclusion: In managing diabetic patients, knowledge of hemoglobinopathies influencing HbA1c determination methods is essential because hemoglobin variants may cause mismanagement of diabetes. Unusual results should prompt further analysis for a hemoglobinopathy as the potential cause of aberrant results.

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