The Value of Duodenal Biopsies in the Evaluation of Megaloblastic Anemia

Introduction Megaloblastic anemia is one of the common causes of anemia in India. Duodenal biopsies are routinely performed in the investigation of megaloblastic anemia. The present study was undertaken to analyze the value of duodenal biopsy in megaloblastic anemia and to correlate endoscopic findings with biopsy. As a secondary aim, the study has also analyzed the hematological profile and vitamin B12 and folate status of these patients. Materials and methods All the cases of megaloblastic anemia with bone marrow studies diagnosed at PSG Institute of Medical Sciences and Research during the two year period from January 2016 to December 2017 were retrieved. Clinical and laboratory findings (serum vitamin B12 and folate levels) and endoscopic findings were retrieved from hospital records of the patients. Duodenal biopsies of these patients reported in the histopathology department were retrieved and reviewed. Statistical analysis was done using SPSS software 20.0. Results There were 93 cases of megaloblastic anemia diagnosed on bone marrow biopsies. Tropical sprue was diagnosed in 49.5% of cases, followed by intraepithelial lymphocytosis (17.2%), peptic duodenitis (17.2%), and no significant pathology in 16% of cases. Pancytopenia was present in 54.8% of cases. Isolated vitamin B12 deficiency including low levels was present in 48.38% and folate deficiency was seen in 4.3% cases; 34.48% cases had both vitamin B12 and folate deficiency. Conclusion The incidence of tropical sprue in megaloblastic anemia is 49.5% in the study. Duodenal biopsy is valuable in the work up of megaloblastic anemia, irrespective of the endoscopic changes in identifying the etiology.

Malabsorption syndromes in the tropics

Causes of secondary malabsorption that are most common in the tropics include (1) progressive wasting in people infected with HIV, which is known as ‘slim disease’; (2) various infections—protozoal (e.g. Giardia lamblia, Cryptosporidium parvum), helminthic (e.g. Capillaria philippinensis, Strongyloides stercoralis), and bacterial (Mycobacterium tuberculosis); (3) immunoproliferative small intestinal disease; and (4) hypolactasia. Coeliac disease and Crohn’s disease also occur. When patients with conditions that can cause secondary malabsorption are excluded, a group remains who have chronic diarrhoea, malabsorption, and its nutritional sequelae. This primary or idiopathic malabsorption syndrome is called ‘tropical sprue’, which occurs against the background of tropical enteropathy (describing the fact that the morphology of the mucosa of normal gut is different in tropical preindustrialized countries from that in temperate-zone industrialized countries). The aetiology of tropical sprue is not known: epidemiological data suggests an infective cause, but no causal agent has been identified. Presentation is typically with loose or watery stools lasting for several weeks or months, and with symptoms and signs of nutritional deficiency. Management involves symptomatic relief from diarrhoea, and correction of fluid and electrolyte abnormalities and nutritional deficiencies. Attempts at specific curative measures—folic acid and tetracyclines—are usually given for up to 6 months.

Anaemia as a challenge to world health

Anaemia is a very common problem in low- and middle-income countries (LMICs): 27% of the world’s population or 1.93 billion people are affected by anaemia (2013) and more than 90% of people with anaemia live in the developing world. Preschool children and women of reproductive age are particularly affected by anaemia and more 60% of anaemia is caused by iron deficiency. Causes of anaemia in LMICs—this is often multifactorial, with causes including (1) nutritional deficiencies—iron, folate, vitamin B12; (2) chronic infection—including malaria, tuberculosis, AIDS; (3) blood loss—hookworm, schistosomiasis; (4) protein–energy malnutrition; (5) malabsorption—for example, tropical sprue; (6) hereditary—for example, thalassaemias, haemoglobin variants, glucose-6-phosphate dehydrogenase deficiency. A series of vicious cycles exist in LMICs—maternal anaemia due to iron or folate deficiency and chronic malaria is associated with the birth of underweight infants who frequently have low iron stores, may also be folate deplete, and are usually anaemic from about 6 months of age. Such infants are prone to infection, particularly gastrointestinal, and may be further depleted of iron or folate by inappropriately prolonged breastfeeding or weaning onto an inadequate diet. They are exposed to hookworm infection as soon as they start to crawl, malaria becomes an important problem after 6 months, and in many populations the increasingly common haemoglobinopathies are a further cause of anaemia after the first few months of life.