Clinical approach to patient with anaemia Flashcards
Anaemia defintion
reduced Hb for age and sex of patient
therefore reduced O2 carriage to tissues
Classification of anaemia
pathogenic i.e. reduced production versus increased loss (bleeding haemorrhage)
Morphological: micro and macrocytic
Haemoglobin vs red cell values
usually haemoglobin and red cell counts both decrease
Occasionally in hypochromic and microcytic anaemia of iron deficiency red cell count is normal although Hb is reduced, due to low Hb content of individual cells
anaemia results form one of 3 fundamental disturbances
impaired red cell formation by bone marrow
blood loss
excess red cell destruction (hemolysis)
Morphological classification based on
Red cell appearance under the microscope
MCV = mean red cell volume
MCHC = mean cell haemoglobin concentration
Normocytic anemia
MCV in normal range, most are also normochromic with normal MCHC, but in some mild hypochromia
Hypo chromic microcytic anemias
MCV and MCHC reduced
Macrocytic anemias
MCV increased, most normochromic some hypo chromic
Two steps in the clinical investigation of anaemia
determination of the morphological type
determination of the cause
Causes of impaired production
deficiency of substances essential for red cell production
- iron, vit B12, folate
Genetic defect in red cell production
- thalassaemia
Failure of bone marrow
- infiltration e.g. leukaemia, irradiation or drug damage
Causes of reduced red cell survival
Blood loss - usually acute e.g. trauma, surgery - note, slow, chronic blood loss gives rise to iron deficincy Haemolysis - shortened survival within the body - environmental or red cell problem
Morphological approach to anaemia
uses MCV, MCHC and blood film
- microcytic hypochromic
- normocytic normochromic
- macrocytcic anemia
Causes of microcytic hypo chromic anaemias
Iron deficiency
Chronic illness - iron block
genetic - thalassemia
Explain anaemia of chronic inflammation
Iron block Mild anemia e.g. 90-100g/L iron studies = normal or raised ferritin low normal Fe Low normal TIBC normal saturation
Diagnosis of iron deficiency
measure: serum iron, iron binding capacity/transferrin and iron saturation
measure serum ferritin
Rarely examine iron stores in bone marrow
NOTE: must identify the cause of iron deficiency
anemia occurs late in iron deficiency
Causes of iron deficiency
Diet - veggie Malabsorption - prog small bowel Increased demands - pregnancy Chronic blood loss - GI or GU tract
Investigations of iron deficiency based on age, gender and maturity status
Children - deficient dietary intake
Premenopausal women - imbalance between dietary intake of iron and menstrual blood loss usual cause, or repeat pregnancies
In males and post menopausal females, occult blood loss from GI tract
Other causes of microcytic anaemia
Anaemia of chronic inflammation or disease - patient with underlying malignancy or inflammatory disease e.g. rheumatoid arthritis
thalassemia
Macrocytic / megaloblastic anemia
vit B12 deficincy
Folate deficiency
- liver disease, hypothyroid, excess alcohol intake
if extremely severe folate or B12 deficincy it can affect other blood lineages, not only only anaemia, white cells and platelet counts can be reduced –> hyper segmented neutrophils
Consequences of B12 / folate deficincy
impaired DNA synthesis
may affect all cell lineages if severe, but initially microcytic anaemia
Measure serum vitamin B12 and folate levels
As in iron deficiency need to determine cause of low B12 or folate level
Causes of a low bit B12 level
Diet, uncommon (vegan) Malabsorption -gastrectomy -immune (pernicious anaemia, antibodies against parietal cells and or intrinsic factor) -terminal ill disease body has stores for 3-4 year
Diagnosis of iron deficiency
measure serum iron, iron binding capacity/ transferrin and iron saturation
Measure serum ferritin
rarely examine iron stores in bone marrow
Hepsidin
transports iron from gut into circulation
Causes of low folate level
Diet - lack of vegges
Malabsorption - e.g. coeliac disease (prog small bowel)
Increased demands or utilisation e.g. pregnancy
Haemolytic anemia
due to increased rate of destruction of red cells
Clin features: pallor, mild jaundice, splenomegaly
Lab findings: features of increasing red cell destruction e.g. raised bilirubin, hepatoglobins
Features of increased red cell production e.g. reticulocytes
- damaged red cells
Classification of haemolytic anaemia
- intrinsic red cell defects usually hereditary e.g. membrane defect
- environmental, usually acquired e.g. autoimmune
Iron deficiency treatment
Iron replacement therapy e.g. ferrogradument
Thalassaemia
Mainly in malaria areas - africa and south east asia
- Heterozygote, mild anemia
- Homozygote, severe anemia
Lab diagnosis, hemaglobinopathy screen and in selected cases genetic testing
