Searchable abstracts of presentations at key conferences in endocrinology
Endocrine Abstracts (2011) 26 P637

ECE2011 Poster Presentations Clinical case reports (73 abstracts)

Diabetes and A1C. How a hemoglobin variant affect A1C test: a case report

M Alves 1 , M Bastos 1 , M Ribeiro 2 , J Santos 1 , A Vieira 1 , S Gouveia 1 , J Saraiva 1 & M Carvalheiro 1

1Serviço de Endocrinologia, Diabetes e Metabolismo, Hospitais da Universidade de Coimbra, EPE, Coimbra, Portugal; 2Serviço de Hematologia, Centro Hospitalar de Coimbra, EPE, Coimbra, Portugal.

Introduction: Glycated hemoglobin A1c (A1C) is used for diagnosis and monitoring diabetic patients. The precision of A1C assay methods is affected by the presence of hemoglobin variants. About 7% of world population is asymptomatic carrier of these variants.

Case report: PCIMR, woman, 42 years old, caucasian, followed in consultation for obesity, primary hypothyroidism and bipolar disorder. Had family history of obesity and sudden death of her father at 50 years old. Was treated with levothyroxine and psychotropic drugs. She reported recent hypertension and weight gain. Presented with BMI 32.5 kg/m2 and BP 140/90 mmHg. Laboratory study showed: TSH 5.6 μUI/ml (NR: 0.4–4.0), FT4 1.2 ng/dl (NR: 0.8–1.9), fasting plasma glucose 108 mg/dl, total cholesterol 182 mg/dl (NR: ≤190), LDL 124 mg/dl (NR:<115), triglycerides 119 mg/dl (NR:<150). Reassessment analysis showed: plasma fasting glucose 106 mg/dl and A1C 14% (NR: 4.0–6.0). After confirmation (A1C 18.5%), we initiated investigation for a hematologic disease.

Results: Hb 14.6 g/dl (NR: 11.5–15.5), hematocrit 42.8% (NR: 37–47), MCV 85.4 fl (NR: 76–96), MCH 29.2 pg (NR: 27–32), MCHC 34.2 g/dl (NR: 31.0–35.6), RDW 13.1%, reticulocyte 1.52%; normal iron metabolism. Suspecting of interference with A1C test, we studied hemoglobins and identified an X variant, with AXA2 hemoglobins profile: Hb A2 2.1% (NR<2), HbF 0.1% (NR: 2–3.5), Hb variant 13.8 g/dl. The HBA1 gene sequencing revealed heterozygosity for mutation of α1 CD40 AAG-AAT (Lys–Asn) – Hb Saratoga Springs. Given the familial transmission risk, we performed family screening in order to genetic counseling.

Conclusions: In this patient, we found abnormal fasting plasma glucose associated with discrepancy of A1C value. We identified a rare variant of hemoglobin A (Hb Saratoga Springs). Despite the advantages of A1C in the diagnosis and monitoring of diabetes, limitations of the method must be taken into account.

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