[Inappropriate low glycated hemoglobin and hemolysis]

Defining trimester-specific reference intervals for carbohydrate deficient transferrin in pregnant women

OBJECTIVES

Extensive consumption of alcohol during pregnancy can lead to severe complications for the unborn child. Carbohydrate-deficient transferrin (CDT) levels in serum have become a common biomarker for excessive alcohol intake. However, during pregnancy CDT levels can rise to levels above commonly used cut-off values, for reasons unrelated to alcohol intake. The aim of this study is to investigate the changes in CDT values during pregnancy and to determine accurate, trimester dependent reference intervals.

METHODS

439 serum samples of 147 healthy pregnant women were obtained for trimester 1, 2, 3, and post-partum and were analysed by high-performance liquid chromatography (HPLC) and an N-Latex immunonephelometric assay. New trimester-specific reference intervals were established.

RESULTS

This study demonstrates there is a trimester-dependent increase of %CDT, as up to 39.4% of the population exceeded the previously established upper reference limit of 1.7%. In our study the estimated upper reference limit for %DST/%CDT were 1.55%, 1.96%, 2.05% and 1.35% for trimester 1, 2, 3 and post-partum for the HPLC-method and 2.02%, 2.19%, 2.19% and 1.96% for the N-Latex immunoassay.

CONCLUSIONS

We demonstrate that CDT levels rise during pregnancy. The magnitude of the increase is method-dependent and needs to be taken into account. We have established method- and trimester-specific reference intervals to prevent false-positive results in alcohol abuse screening tests during pregnancy.

The ICET-A Recommendations for the Diagnosis and Management of Disturbances of Glucose Homeostasis in Thalassemia Major Patients

Iron overload in patients with thalassemia major (TM) affects glucose regulation and is mediated by several mechanisms. The pathogenesis of glycaemic abnormalities in TM is complex and multifactorial. It has been predominantly attributed to a combination of reduced insulin secretory capacity and insulin resistance. The exact mechanisms responsible for progression from norm glycaemia to overt diabetes in these patients are still poorly understood but are attributed mainly to insulin deficiency resulting from the toxic effects of iron deposited in the pancreas and insulin resistance. A group of endocrinologists, haematologists and paediatricians, members of the International Network of Clinicians for Endocrinopathies in Thalassemia and Adolescence Medicine (ICET-A) convened to formulate recommendations for the diagnosis and management of abnormalities of glucose homeostasis in thalassemia major patients on the basis of available evidence from clinical and laboratory data and consensus practice. The results of their work and discussions are described in this article.

Immeasurable glycosylated haemoglobin: a marker for severe haemolysis

Glycosylated haemoglobin (HbA1c) is a measurement commonly performed in patients with diabetes. Factors causing a change in the life span of the red blood cell (RBC) can affect the measurement of HbA1c. Thus haemolysis is an important factor that may affect the HbA1c level determination. Haemolysis has been shown to cause a falsely low HbA1c. A 62-year-old man with a history of autoimmune haemolytic anaemia was admitted for severe haemolytic anaemia and an Hb of 2.9 g/dL. HbA1c tested during hospitalisation was unrecordable due to the extremely low Hb. The patient was treated with intravenous steroids, immunoglobulin, fluids and RBC transfusions but continued to haemolyse and eventually expired. We emphasise that an extremely low HbA1c level can serve as a marker of haemolysis and an unrecordable HbA1c level may point towards fatal haemolysis.

Absorption spectroscopy for the estimation of glycated hemoglobin (HbA1c) for the diagnosis and management of diabetes mellitus: a pilot study

OBJECTIVE

The purpose of this study was to explore the possibility of using absorption spectroscopy technique for the estimation of glycated hemoglobin HbA1c (%).

BACKGROUND DATA

Glycated hemoglobin (HbA1c) is an important marker in the diagnosis and management of diabetes mellitus. Different assay techniques have been employed for the estimation of glycated hemoglobin, including ion exchange high performance liquid chromatography (HPLC), electrophoresis, affinity chromatography, immunoturbidimetric assay and colorimetric assays, which measure different glycated products and report using different units. Spectroscopic measurements have been shown to be very sensitive and nondestructive, and require very little quantity of material for analysis. In the present study, we have employed absorption spectroscopy technique for the estimation of glycated hemoglobin in hemolysate samples of diabetic patients.

MATERIALS AND METHODS

The blood samples of individuals with normal glycemic status and confirmed diabetic patients were collected from the Clinical Biochemistry Laboratory, Kasturba Hospital, Manipal. The absorption spectra of glycated hemoglobin (HbA1c) samples were recorded in the spectral range 200-850 nm using an optic fiber based Ocean Optics CHEMUSB4-UV-VIS single beam spectrophotometer. The parameter "area under the curve" of each baseline corrected absorption spectrum was used for the estimation of HbA1c (%). The glycated hemoglobin values obtained by this spectroscopic method were compared with the values reported by the standard ion exchange HPLC method.

RESULTS

A total of 30 absorption spectra were recorded from hemolysate samples with HbA1c (%) in the range 4-10.5%. A good correlation was observed between the glycated hemoglobin values obtained by the spectroscopic method and those obtained by the standard HPLC method.

CONCLUSIONS

It appears that the direct absorption spectroscopy of hemolysate samples, therefore, may be utilized as a supplementary technique for the estimation of HbA1c (%), even at the primary healthcare centers.