Persistent fetal haemoglobin and falsely high glycosylated haemoglobin levels

Some of the routine methods of measuring glycosylated haemoglobin depend on its difference in charge from haemoglobin A and do not distinguish between glycosylated haemoglobin and fetal haemoglobin. Two insulin dependent diabetics showed persistent discrepancies between their capillary blood glucose values and their glycosylated haemoglobin values measured by agar gel electrophoresis: the blood values were normal but the glycosylated haemoglobin values were raised. In one patient increases in insulin dose in response to the glycosylated haemoglobin results repeatedly produced hypoglycaemia. Both patients were found to have higher than normal concentrations of fetal haemoglobin; and when measured by the thiobarbituric acid reaction their glycosylated haemoglobin levels were almost normal. This problem may be avoided by using a method that distinguishes between fetal and glycosylated haemoglobin or by testing glycosylation of hair or serum albumin if discrepancies arise. This is particularly important during pregnancy, when some women have an increase in fetal haemoglobin.     

Updating of hereditary haemoglobin disorders

Hereditary haemoglobin disorders (E-beta Thalassaemia & Thalassaemia) are inherited as recessive disorders so that the heterozygote subjects are generally healthy. They commonly present with progressive pallor, thalassaemic facies, splenohepatomegaly & growth retardation. Diagnosis of carriers & patients are usually confirmed by haemoglobin electrophoresis. Transfusion-chelation therapy is usually employed for their treatment. Allogenic bone marrow transplantation is the only definite cure. Gene therapy remains to be the major challenging goal of future curative therapy. During the last 10 years wit medical advances, the number of pregnancies in thalassaemia is increasing. Normal pregnancy can be maintained with regular packed blood cells transfusion given carefully. In Bangladesh, HHD can be prevented by I. carrier identification and marriage counseling, II. passing and enforcing laws against marriage between two carriers, III. introducing thalassaemia in school curriculum and IV. creating public awareness.     

Aberrantly high glycated haemoglobin measurement due to the haemoglobin variant Hb Santa Juana

Various laboratory and patient-related factors can result in falsely high or low glycated haemoglobin (HbA1c) measurements, and haemoglobin (Hb) variants that interfere with laboratory readings is an important cause of this. We report a case of a rare Hb variant, Hb Santa Juana, manifesting as a falsely high HbA1c in a 62-year-old patient with type 2 diabetes mellitus. The patient presented with high HbA1c values that persisted despite the intensification of anti-diabetic treatment. His home blood glucose levels were incongruently low compared to his HbA1c values. Further investigations revealed a family history of the variant Hb Santa Juana. This was confirmed in the patient when his blood was sent for DNA analysis. It is important for clinicians to be aware of the factors that can influence laboratory HbA1c measurements, as clinical decisions on treatment are often based on these measurements.     

Glycosylated haemoglobin concentrations in mothers of large babies

Mothers who have big babies may have had abnormal glucose tolerance during pregnancy. Glycosylated haemoglobin (HbA1) concentrations were measured on the first or second day after delivery in 50 women who had had babies weighing over the 95th centile for gestational age and in 50 women who had had normal-sized babies (controls). Nine of the mothers of big babies but only one of the controls had an HbA1 concentration above the normal range. All the women had normal glucose tolerance and HbA1 concentrations six weeks after delivery. Measuring HbA1 concentration in the first two days after delivery in mothers of large babies may identify gestational diabetics.