ORIGINAL ARTICLE

Conditions associated with very low values of glycohaemoglobin measured by an HPLC method

J L Camargo¹, J L Gross²

¹ Clinical Pathology Department, Hospital de Clínicas de Porto Alegre, Porto Alegre, Brazil
² Endocrinology Division, Hospital de Clínicas de Porto Alegre

Correspondence to:
Correspondence to:
Dr J L Gross
Serviço de Endocrinologia, Hospital de Clínicas de Porto Alegre, Rua Ramiro Barcellos, 2350 Prédio 12, 4⁰ andar, Porto Alegre, RS, Brazil, 90035-003; jorgegross{at}terra.com.br; jcamargo{at}hcpa.ufrgs.br

Aims: To identify the causes of very low glycohaemoglobin (GHb) values in a sample of patients with diabetes in southern Brazil using high performance liquid chromatography.

Methods: Between August 1996 and December 2001 all samples from patients with diabetes at a university hospital with GHb values below the reference range (4.7–6.0% HbA_1c) were submitted to cellulose acetate electrophoresis. Medical records were reviewed to identify conditions that might be associated with these low values.

Results: Among 29 657 samples analysed, 130 patients had GHb < 4.7%. Seventy three patients (56%) were heterozygous for HbS, HbC, or HbD (19 black, two mulatto, and 52 white patients). The other 57 patients (44%) without Hb variants had low haematocrit and haemoglobin values (42 patients) or other conditions such as pregnancy, lipaemia, malignancy, cirrhosis, acetylsalicylic acid use, and absence of diabetes (15 patients).

Conclusions: The presence of an Hb variant may falsely lower GHb measurements. However, anaemia is also a source of negative interference. The haematological status should be considered for the correct interpretation of GHb results.

Keywords: glycated haemoglobin; metabolic control; variant haemoglobin; anaemia

Abbreviations: CV, coefficient of variation; DCCT, Diabetes Control and Complications Trial; GHb, glycohaemoglobin; Hb, haemoglobin; HbA_1c, glycated haemoglobin; HPLC, high performance liquid chromatography

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• Kilpatrick, E S (2004). HbA1c measurement. J. Clin. Pathol. 57: 344-345 [Full Text]