The condition characterised by inadequate red blood cells and/or HAEMOGLOBIN in the BLOOD. It is considered to exist if haemoglobin levels are below 13 grams per 100 ml in males and below 12 grams per 100 ml in adult non-pregnant women. No simple classification of anaemia can be wholly accurate, but the most useful method is to divide anaemias into: (a) microcytic hypochromic (small, pale red blood cells) or iron deficiency anaemia; (b) megaloblastic hyperchromic anaemia (large, immature blood cells which are not pale); (c) aplastic anaemia (an absence of blood cells); (d) haemolytic anaemia (where blood cells have disintegrated); (e) inherited anaemias (seebelow).
In Britain, anaemia is much more common among women than men. Thus, around 10 per cent of girls have anaemia at the age of 15, whilst in adult life the incidence is over 30 per cent between the ages of 30 and 40; around 20 per cent at 50; and around 30 per cent at 70. Among men the incidence is under 5 per cent until the age of 50; it then rises to 20 per cent at the age of 70. Ninety per cent of all cases of anaemia in Britain are microcytic, 7 per cent are macrocytic, and 3 per cent are haemolytic or aplastic. Inherited anaemias include sickle-cell anaemia and THALASSAEMIA.
As a result of trauma. This is perhaps the simplest example of all, when, as a result of an accident involving a large artery, there is severe haemorrhage.
Menstruation. The regular monthly loss of blood puts a strain on the blood-forming organs. If this loss is excessive, then over a period of time it may lead to anaemia.
Childbirth. Blood is always lost at childbirth; if this is severe, or if the woman was anaemic during pregnancy, significant anaemia may result.
Bleeding from the gastrointestinal tract. One example of this is anaemia due to ‘bleeding piles’ (see HAEMORRHOIDS). Such bleeding, even though slight, is a common cause of anaemia in both men and women if maintained over a long period of time. The haemorrhage may be more acute and occur from a DUODENAL ULCER or gastric ulcer (see STOMACH, DISEASES OF), when it is known as haematemesis.
Drugs. Certain drugs, such as aspirin and the non-steroidal anti-inflammatory drugs, may cause occult gastrointestinal bleeding.
Certain blood diseases, such as PURPURA and HAEMOPHILIA, which are characterised by bleeding.
This is the main cause of anaemia in infections. The micro-organism responsible for the infection affects the blood-forming organs, just as it does other parts of the body.
In conditions such as chronic glomerulonephritis (see KIDNEYS, DISEASES OF) and URAEMIA there is a severe anaemia due to the effect of the disease upon blood formation.
This may occur in diseases of intestinal malabsorption. (See MALABSORPTION SYNDROME.)
The daily requirement of iron for an adult is 12 mg, and 15–20 mg for an adult woman during pregnancy. This is well covered by an ordinary diet but if there is a steady loss of blood, as a result of heavy menstrual loss or chronic use of aspirin or non-steroidal anti-inflammatories, the intake of iron in the diet may not be sufficient to maintain adequate formation of haemoglobin.
These depend upon whether the anaemia is sudden in onset, as in severe haemorrhage, or gradual. Mild anaemia usually causes no discernible symptoms. In severe anaemia, the striking sign is pallor, with the best guide being the colour of the internal lining of the eyelid. When the onset of the anaemia is sudden, the patient complains of weakness and giddiness, and loses consciousness if he or she tries to stand or sit up. The breathing is rapid and distressed, the pulse is rapid and the blood pressure is low. In chronic cases the tongue is often sore (GLOSSITIS), and the nails of the fingers may be brittle and concave (koilonychia) instead of convex. In some cases, particularly in women, the Plummer-Vinson syndrome is present: this consists of difficulty in swallowing and may be accompanied by huskiness; in these cases glossitis is also present.
If, of course, there is haemorrhage, this must be arrested, and if the loss of blood has been severe it may be necessary to give a blood transfusion (see TRANSFUSION – Transfusion of blood).
If there is any underlying metabolic, cancerous, toxic or infective condition, these, of course, must be adequately treated after appropriate investigations. Otherwise treatment consists primarily of giving sufficient iron by mouth to restore, and then maintain, a normal blood picture. When the blood picture has become normal, the dosage is gradually reduced.
Care must be taken to ensure that the patient is having an adequate diet.
In this type of anaemia, there are fewer than normal but large blood cells which are not pale. There are various forms, such as those due to nutritional deficiencies, but the most important is that known as pernicious anaemia.
An autoimmune disease in which sensitised lymphocytes (see LYMPHOCYTE) destroy the PARIETAL cells of the stomach. These cells normally produce INTRINSIC FACTOR, the carrier protein for vitamin B12 (see APPENDIX 5: VITAMINS) that permits its absorption in the terminal part of the ILEUM. Lack of the factor prevents vitamin B12 absorption and this causes macrocytic (or megaloblastic) anaemia. The disorder can affect men and women, usually those over the age of 40; onset is insidious, so it may be well advanced before medical advice is sought. The skin and MUCOSA become pale, the tongue is smooth and atrophic and is accompanied by CHEILOSIS. Peripheral NEUROPATHY is often present, resulting in PARAESTHESIA and numbness and sometimes ATAXIA. A rare complication is subacute combined degeneration of the SPINAL CORD.
consists of injections of vitamin B12 in the form of hydroxycobalamin which must be continued for life.
In this condition, the bone marrow makes few or no red blood cells. The cause in many cases is not known, but in some it is due to a toxic substance, such as benzol or certain drugs, or ionising radiations. The patient becomes very pale, with a tendency to haemorrhages under the skin and mucous membranes. Treatment consists primarily of regular blood transfusions. In severe cases, promising results are being reported after bone-marrow transplantation.
results from the excessive destruction, or HAEMOLYSIS, of the red blood cells. This may be the result of undue fragility of the cells, when the condition is known as congenital haemolytic anaemia, or as a result of an immune reaction or toxic effect of a drug. One form of haemolytic anaemia is sickle cell anaemia, occurring in persons of African descent, so-called because of the sickle shape of the red blood cells. It is an inherited condition of abnormal haemoglobin, the pigment in blood cells which transports oxygen around the body. The abnormal HAEMOGLOBIN, haemoglobin S, is in the form of a rod and causes red blood cells to become sickle-shaped. These cells have a tendency to stick to the walls of small blood vessels, slowing blood flow with the result that less oxygen is released to tissues. This can cause THROMBOSIS and areas of tissue INFARCTION may follow, causing severe pain, swelling and tenderness, the so-called sickle-crisis. Sickle cells are more fragile than normal red blood cells, and have a shorter life span, hence the anaemia.