This condition is due to a genetic defect in which cell survival time is reduced. The erythrocyte destruction is aggravated by stress, such as pregnancy, and pallor is common, together with a reduced mean haemoglobin concentration, although the serum iron is raised. Since there is an excess rather than a deficiency of body iron, iron therapy is contra- indicated. The disease should be considered if a patient of Mediterranean stock fails to respond to oral or parenteral iron. The only treatment is blood transfusion and this should be withheld unless a haemolytic crisis develops.
The inheritance of a defective gene which alters the locus on the chromosome responsible for haemoglobin synthesis leads to the production of abnormal haemoglobins. Erythrocytes containing abnormal haemoglobin have a greatly reduced life and episodes in which destruction of the erythrocytes increases suddenly occur, causing a profound anaemia. This may be associated with infarction, especially in bones, because of sludging of the erythrocytes in the capillaries.
These clinical effects are seen in individuals who are homozygous for the gene, or heterozygous for two genes at the same locus. The most common abnormal haemoglobin is the sickle cell (S) one. This originated in the Middle East and has spread to Central Africa, Southern Europe and India. The highest incidence being in Uganda where 45% of the population are affected. Another abnormal haemoglobin, C, is found in Ghana, and both haemoglobin S and C have reached the United States, the Caribbean and South America with slave migrants. In South-East Asia, particularly Thailand, haemoglobin E is found.
Although fertility is not lowered and the incidence of abortion is not increased, the diseases cause a considerable morbidity and mortality in pregnant women, particularly if sickle cell anaemia develops. The anaemia thick, anaemia, which is haemolytic, may developwith extreme rapidity in pregnancy and is accompanied by a megaloblastic erythropoiesis in many cases, as insufficient folic acid is available for the needs of the fetus and the rapid erythropoiesis. It can largely be prevented by administration of folic acid during pregnancy and if it occurs is more likely in the last trimester.
If the destruction of the erythrocytes is exceptionally rapid, it may be followed by enlargement of the liver and spleen and by sludging in the capillaries leading to the acute bone pain crisis. This sludging is enhanced by hypoxia, by dehydration, by acidosis and by trauma and is therefore more common in labour. The main danger of the infraction in bone, which occurs distally to the occlusion of the capillaries, is fat embolus, and this is often preceded by a pseudotoxaemia.
This abnormal haemoglobin causes fewer abnormalities but is a cause of refractory megaloblastic anaemia in pregnancy. If the trait affects the baby, haemolysis of fetal cells tan occur in utero with the birth of a hydropic stillborn infant, and a large oedematous placenta. The findings resemble those of Rhesus iso-immunization, but the latter is very rare amongst the peoples of South-East Asia. Treatment
In areas where sickle cell disease and thalassaemia are common, or if patients come from such areas, antenatal care should be directed to the early detection of the disorder, and particularly of anaemia. Folic acid should be prescribed for all patients, and frequent haemoglobin estimations made. If the haemoglobin falls below 6 g. per 100 ml. direct or exchange transfusion is required, and this may need to be repeated during pregnancy.
Should bone pain crisis develop, the haemoglobin level must be estimated every 4 hours and a drop of more than 2 g. indicates the need for exchange transfusion Heparin, given to maintain the clotting time at more than 20 minutes, appears to reduce the severity of the bone pain and the incidence of emboli. If ‘pseudotoxaemia’ develops during an episode of bone pain, urgent delivery is recommended.
Tom Brady is a really great rubber stamp maker. He is an expert on forex trading online.
He has been consulted on and speaks about frequently on related matters such as free forex video lessons.
Mike has studied acting and has often commented on his website about popular topics such as forex calendar
and is today considered one of the foremost experts on the topic.
More Goodies For You
Recent Comments