A survey and critical evaluation of a dual isotope (Dicopac) vitamin B12 absorption test

A systematic approach to the assessment of erythropoiesis

The pathogenesis of anaemia may be simple or complex and the differential diagnosis can be difficult. An appreciation of the erythropoietic processes is required, together with regular review of investigations, to ensure that appropriate protocols are adopted. The application of tests, which define different facets of erythropoiesis, should be appropriate to the clinical circumstances. In some situations, such as the anaemia of chronic disorders, pregnancy and chronic renal failure, a detailed analysis of erythropoiesis is often required. Guidelines for investigating anaemia due to megaloblastosis or haemoglobinopathy are well established, whereas disturbances of iron metabolism are often difficult to classify. These require a clear distinction between storage and functional iron to differentiate whether the defect is due to readily treatable simple iron deficiency or more complex mechanisms, which do not respond to iron supplementation. Determination of red cell haemoglobin content, reticulocyte analysis and the assay of serum transferrin receptors are new generation parameters developed to address this. Practice pressures and new treatment options have contributed to investigations becoming more complex, especially those of the secondary anaemias, as new tests have become more readily available and often automated. This has resulted in reduced turnaround times and clinical demand has driven request patterns. Initiatives to develop evidence-based anaemia management protocols are welcomed but, wherever possible, should be developed through collaboration between the haematology department and the user unit, and based on available guidelines.

Type 1 diabetes and latent pernicious anaemia

OBJECTIVE

To determine the prevalence of latent pernicious anaemia (PA) in Type 1 diabetics.

DESIGN

Patients with Type 1 diabetes were screened at two yearly intervals on a continuing basis.

SETTING

Diabetic Unit, Royal Perth Hospital, Western Australia.

PATIENTS

Three hundred and seventy-one patients, 156 females and 215 males, attending a diabetic clinic. They were classified as having Type 1 diabetes on the basis of age of onset less than 40 years and requiring insulin from the start.

MAIN OUTCOME MEASURES

Serum cobalamin levels were measured and studies of thyroid function and a blood count were done. Patients with a reduced serum level of cobalamin had tests for cobalamin absorption.

RESULTS

Six patients had a low serum cobalamin level; five showed malabsorption of the vitamin which could be corrected by the addition of intrinsic factor. Four of these patients had no clinical signs of PA. The fifth was mildly anaemic (haemoglobin level 111 g/L) and had megaloblastic bone marrow. He was classified as having frank PA. The sixth patient was not available for further testing. These results give a prevalence of latent PA of 11 per 1000 in Type 1 diabetics, compared with 3.9 per 1000 in diabetics with clinically manifest disease and 1.27 per 1000 in the general population. All four patients with latent PA had hypothyroidism, based on low thyroxine levels, increased levels of thyroid stimulating hormone and the presence of thyroid antibodies.

CONCLUSION

Latent PA is not uncommon in Type 1 diabetics. It has a long preclinical course and occurs in those patients with thyroid disease. The screening of Type 1 diabetics for latent PA has worthwhile benefits as a "preventive" health measure.