title: A rare haemoglobin variant (Hb Phnom Penh) manifesting as a falsely high haemoglobin A1c value on ion-exchange chromatography.
abstract: Most haemoglobin (Hb) variants are clinically silent. However, some Hb variants may interfere with the measurement of haemoglobin A1c (HbA1c), resulting in spurious values depending on the assays used. We herein report the case of a 53-year-old Taiwanese man with type 2 diabetes mellitus, who presented with an abnormal HbA1c peak on ion-exchange chromatography. Additional investigations, including intensified self-monitored blood glucose tests, an alternative HbA1c assay, and a glycaemic indicator based on a different method, revealed that the HbA1c values were falsely elevated. Subsequent DNA analysis confirmed that the patient was heterozygous for the insertion of an isoleucine residue at codons 117/118 of the a1-globin gene, Hb Phnom Penh. Clinical laboratorians should be aware of the interfering factors in their HbA1c analysis. Cautious inspection of the chromatogram may provide a valuable clue to the presence of an Hb variant.
authors.affiliation: Department of Anaesthesia and Intensive Care, Government Medical College and Hospital, Chandigarh, India. kapoor.dheeraj72@gmail.com.
authors.forename: Chi-Fen
authors.initials: CF
authors.lastname: Chen
authors.affiliation: Department of Internal Medicine, Yuan's General Hospital, No. 162, Chenggong First Road, Ling Ya District, Kaohsiung, 802 Taiwan. yk.tai@msa.hinet.net.
authors.forename: Yen-Kuang
authors.initials: YK
authors.lastname: Tai
mesh_terms: D002851:Chromatography, High Pressure Liquid; D002852:Chromatography, Ion Exchange; D048909:Diabetes Complications / Q000097:blood; D003924:Diabetes Mellitus, Type 2 / Q000097:blood / Q000150:complications; D050171:Dyslipidemias / Q000097:blood / Q000150:complications; D006455:Hemoglobins, Abnormal / Q000032:analysis*; D006801:Humans; D006973:Hypertension / Q000097:blood / Q000150:complications; D007003:Hypoglycemia / Q000097:blood; D008297:Male; D008875:Middle Aged; D015203:Reproducibility of Results; D017422:Sequence Analysis, DNA; D013624:Taiwan
chemical_list: D006455:Hemoglobins, Abnormal; C119639:hemoglobin Phnom Penh