Overview of Nutritional Anaemias.pdf

Overview of Nutritional Anaemias Introductory Posting in Pathology & Pharmacology Course: HAE 311 By: Dr. Adeyemi  Overview of Anaemia Anaemia is defined as a reduction in the concentration of circulating haemoglobin or oxygen-carrying capacity...

Overview of Nutritional Anaemias Introductory Posting in Pathology & Pharmacology Course: HAE 311 By: Dr. Adeyemi  Overview of Anaemia Anaemia is defined as a reduction in the concentration of circulating haemoglobin or oxygen-carrying capacity of blood below the level that is expected for healthy persons of same age and sex in the same environment. The World Health Organisation (WHO) defines anaemia by the following haemoglobin (Hb) concentrations: Males < 130 g/L (130-175 g/L) Females < 120 g/L (120-155 g/L)* – * In pregnancy, a Hb < 110 g/L is diagnostic Anaemia can be classed based on aetiology and morphology  CLASSIFICATION OF ANAEMIA Aetiological The aetiological approach addresses the underlying mechanism leading to the reduction in Hb concentration. Aetiologically, causes can be arranged into three groups: Decreased RBC production Increased RBC destruction Blood loss  CLASSIFICATION OF ANAEMIA Morphological The morphological approach categorises anaemia based on the size of RBCs (e.g. the mean corpuscular volume). This approach arranges anaemia into three groups: Microcytic (small RBCs) Normocytic (normal sized RBCs) Macrocytic (large RBCs) Aetiological Classification of Anaemia Aetiological Classification of Anaemia: 1 Aetiological Classification of Anaemia: 2  Aetiological Classification of Anaemia: 3 Blood loss Blood loss is a common cause of anaemia, it may be obvious (e.g. trauma, haematemesis) or occult (e.g. gastrointestinal malignancy). Erythrocytes form a major store of iron within the body. This means a loss of erythrocytes could lead to the development iron deficiency anaemia (IDA). – Consequently, IDA commonly reflects blood loss from an unidentified source that requires further investigation. Two common sources of blood loss include menstruation in young females and gastrointestinal bleeding in older populations. Morphological Classification of Anaemia Morphological Classification of Anaemias  NUTRITIONAL ANAEMIAS The anaemia that results from deficiencies of vitamin B12, folic acid or iron are, in general, clearly defined and are relatively common. In contrast, characteristics of anaemia that may occur with deficiencies of the other vitamins and minerals are poorly defined and relatively rare in humans. When present, they usually exist not as isolated deficiencies of one vitamin or one mineral, but rather, as a combination of deficiencies resulting from malnutrition or malabsorption  Nutritional Anaemias The most common are megaloblastic anaemia, resulting from folic acid or vitamin B12 deficiency, and microcytic, hypochromic anaemia, resulting from iron (Fe) deficiency. The fat-soluble vitamins A and E, water-soluble vitamins B2 (riboflavin), B6 (pyridoxine), and C (ascorbic acid) and deficiencies of the micro- minerals such as copper and zinc have been implicated as causes of anaemia in humans.  Nutritional Anaemias The two criteria for defining a nutritional anaemia are that: – (1) Deficiency or lack of a specific nutrient must cause the anaemia – (2) Replacement of that specific nutrient must correct the anaemia. Anaemias resulting from the aforementioned deficiencies of vitamins and minerals may not directly conform to these two criteria, because isolated deficiencies are rare, and an anaemia may not be directly related to a single nutrient deficiency, but most often is complicated by other nutrient deficiencies. IRON DEFICIENCY ANAEMIA (IDA)  ROLE OF IRON IN THE BODY Iron is a key element in the metabolism of nearly all living organisms. Iron is a component of heme, which is the active site of electron transport in cytochromes and cytochrome oxidase involved in mitochondrial energy generation. Functions of iron include – involvement in energy metabolism – gene regulation – cell growth and differentiation – oxygen binding and transport – muscle oxygen use and storage – enzyme reactions – neurotransmitter synthesis – protein synthesis  Iron Compartments in Normal Humans Compartment Form and Percent of Total Body Typical Iron Content Anatomical Site Iron (g) Functional Haemoglobin iron in ~ 68 2.400 the blood Myoglobin iron in ~ 10 0.360 muscles Peroxidase, catalase, ~3 0.120 cytochromes, riboflavin enzymes in all cells Storage Ferritin and ~ 18 0.667 haemosiderin mostly in macrophages and hepatocytes; small amounts in all cells except mature red blood cells Transport Transferrin in plasma 120fL – Leucocyte count – Low or normal – Platelet – Low or normal – Reticulocyte count- Low for degree of anaemia Blood film‐ Oval macrocytes, anisopoikilocytosis, fragmented red cells, neutrophil hypersegmentaion. Bone marrow – Increased cellularity, megaloblastic changes in erythroid series-well Haemoglobinized erythroblast with less matured nucleus (Nuclear cytoplasm maturation asynchrony), increased early basophylic erythroblast, giant metamyelocytes, dysplastic megakaryocytes. Serum ferittin, iron- Elevated Plasma Lactate dehydrogenase – Elevated, often markedly  Investigations Raised unconjugated bilirubin Reduced haptoglobulins Urine- raised urobilinogen Serum folate (3ug – 15ug)- low in all folate deficient patients. Affected by recent diet. Elevated or normal in B12 deficiency Red cell folate(160ug – 640ug)-test of body folate stores. Decreased in folate deficiency. Normal or low in B12 deficiency Serum Cobalamin (160/200ng/L – 1000ng/L)- Levels