Iron deficiency anaemia

This article is no. 2 of the anaemia series. Next article: anaemia of chronic disease. Previous article- Anaemia.

Aetiology

Iron deficiency anaemia (IDA) is the most frequent in children due to rapid growth (adolescence) and poor diets (infants), and in peri and post -menopausal women due to rapid growth (pregnancy) and underlying conditions. Anaemia typically presents, in around 50% of cases as headache, lethargy and pallor depending on the severity. Less common side effects include organomegaly and Pica which occurs in patients with zinc and iron deficiency and is defined by the eating of things with little to no nutritional value.

Pathophysiology

Iron is primarily sourced through diet, as haem (Fe2+) and non-haem iron (Fe3+). Fe2+ is sourced through meat, fish, and other animal-based products, Fe2+ can be absorbed directly through the enterocyte via the haem carrier protein1 (HCP1). Fe3+ is less easily absorbed and is mostly found in plant-based products. Fe3+ must be reduced and transported through the duodenum by the enzyme duodenal cytochrome B (DcytB) and the divalent metal transporter 1 (DMT1), respectively.

Diagnosis

As with any diagnosis, the first test to run would be a full blood count and this will occur with all the anaemias. In suspected cases of anaemia, the Haemoglobin (Hb) levels would be lower than 130 in males and 120 in females. The mean cell volume (MCV) is a starting point for pinpointing the type of anaemia, for microcytic anaemias you would expect to see an MCV < 80. Iron studies are best for diagnosing anaemias, for IDA you would expect most of the results to be low. A patient with IDA has little to no available iron so the body would halt the mechanism’s for storing iron. As ferratin is directly related to storage, low ferratin can be a lone diagnostic of IDA. Total iron-binding capacity (TIBC) would be expected to be raised, as transferrin transports iron throughout the body, the higher it is the more iron it would be capable of binding to.

Elliptocytes (tear drop) are elongated RBC, often described as pencil like in structure and are regularly seen in IDA and other anaemias. Typically, one would see hypochromic RBC as they contain less Hb than normal cells, the Hb is what gives red cells their pigment. It’s not uncommon to see other changes in RBC such as target cells, given their name due to the bullseye appearance. Target cells are frequently seen in cases with blood loss.

Summary

IDA is the most frequent anaemia affecting patients of all age ranges and usually presents with lethargy and headaches. Dietary iron from animal derivatives are the most efficient source of iron uptake. Diagnosis of IDA is through iron studies, red cell morphological investigations alongside clinical presentation, to rule out other causes.

By Lauren Kelly