Anémie v těhotenství - review (1. část)

Anaemia during Pregnancy - Review

Anaemia in pregnancy is defined as a decrease of haemoglobin concentration and/or of hematoc-rit by 2 standard deviations below normal values. WHO defines a haemoglobin concentration of110 g/l and a hematocrit of 0,32 as the lower limits of the norm. Iron deficiency (ID) is defined asa decrease of ferritin concentration below 12 mg/l.Iron deficiency anaemia (IDA) is the most common anaemia in pregnancy, megaloblastic anaemia- due to folate or vitamin B12 deficiency - are seen less frequently. Haemoglobinopathies, such asbeta-thalassemia minor and sickle-cell disease, are spread in the endemic areas. In the developingcountries, the aetiology of anaemia in gestation is often combined (malnutrition, malaria, chronicinfections, parasitosis etc.).The prevalence of iron deficiency is very high in woman of fertile age, even in the developedcountries. the prevalence of anaemia in pregnancy varies depending on the demographic region,trimester of gestation and parity. The prevalence of IDA in pregnancy is high (20-60%) but in thedeveloped countries milder cases predominate. A higher incidence of pregnancy anaemia is associated with the following factors of groups: lower social and economic status, history of irregularuterine bleeding or hypermenorrhea, multiparity, multiple pregnancy, consecutive pregnanciesin short intervals, adolescent mothers, a vegetarian diet, and blood donorship.A higher consumption of iron in pregnancy, due to accelerated erythropoesis and demands offoetus and placenta which can not be compensated by usual diet, plays a major role in thepathophysiology of IDA in gestation. There arises a negative iron balance, iron deficiency andlater on iron deficiency anaemia, which is deepen by peripartal blood loss and lactation in thepuerperal period.Changes in the markers of iron stores are the laboratory signs first worsened: decreased ferritinconcentration, increased total iron binding capacity, and transferrin concentration.Recently the serum transferrin receptor (s TfR) is being used, even in obstetrics, as a marker ofIDA (raised concentration), because it is not influenced by the acute phase reaction. The typicalpicture of microcytic, hypochromic anaemia appears, when the iron deficiency worsens: decrea-sed haemoglobin concentration, hematocrit, and red cell count. The ferritin concentration is stillthe most valuable marker of the mobilizable stored iron in gestation, although its reliability islimited (infection, gestational diabetes etc.). Clinically, anaemia in pregnancy is frequently latent.The usual symptoms (fatigue, vertigo, headaches, palpitations, dyspnea) appear only in the case ofrapid or severe anaemia, most often in the puerperal period.The mostly listed clinical risks associated with IDA in pregnancy concern the mothers health(more operative and prolonged deliveries, more frequent need of transfusion, inclination to preec-lampsia, lactation disorders, lower resistance to infection), foetal development (abortions, IUGR,premature deliveries) and neonatal outcome (higher perinatal morbidity and mortality, worsepostpartum adaptation, disorders of psychomotor development). The results of many studies andreviews are inconsistent. Nevertheless most of the authors and medical institutions recommendiron supplementation of selected pregnant women in at least the second half of gestation.IDA is treated with 100-200 mg of elementary iron orally a day, in the case of prophylactic substi-tution with 60-80 mg a day. Retarded preparations containing ferrous iron ions are the mostadvantageous. The addition of folic acid is indicated in megaloblastic anaemia (multiple pregnan-cy, winter time). There is no causal therapy of hemoglobinopathies, repeated blood transfusionsare often needed to prevent dangerous haemolytic crises. Perinatology centres manage the prena-tal diagnosis of these inhereted anaemia in foetuses of mothers at risk.

Key words:
anaemia, depleted iron stores, ferritin, folate deficiency anaemia, haemoglobinopathi-