Anaemia Flashcards
What is anaemia?
Anaemia is defined as a low level of haemoglobin in the blood. This is the result of an underlying disease and is not a disease itself. The prefix an- means without and the suffix -aemiarefers to blood.
Briefly describe the role of haemoglobin
Haemoglobin is a protein found in red blood cells. It is responsible for picking up oxygen in the lungs and transporting it to the cells of the body. Iron is an essential ingredient in creating haemoglobin and forms part of the structure of the molecule. When a patient has a low level of haemoglobin, they have a condition called anaemia.
What is the most common cause of anaemia in infancy?
Physiologic anaemia of infancy causes most cases of anaemia in infancy.
Other than physiologic anaemia of infancy, what else can cause anaemia in infancy?
Physiologic anaemia of infancy causes most cases of anaemia in infancy.
The other causes of anaemia in infants are:
- Anaemia of prematurity
- Blood loss
- Haemolysis
- Twin-twin transfusion, where blood is unequally distributed between twins that share a placenta
Haemolysis is a common cause of anaemia in infancy. There are a number of causes of haemolysis in a neonate:
- Haemolytic disease of the newborn (ABO or rhesus incompatibility)
- Hereditary spherocytosis
- G6PD deficiency
Briefly describe physiologic anaemia of infancy
There is a normal dip in haemoglobin around six to nine weeks of age in healthy term babies. High oxygen delivery to the tissues caused by the high haemoglobin levels at birth cause negative feedback. Production of erythropoietin by the kidneys is suppressed and subsequently there is reduced production of haemoglobin by the bone marrow. The high oxygen results in lower haemoglobin production.
Briefly describe anaemia of prematurity
Premature neonates are much more likely to become significantly anaemic during the first few weeks of life compared with term infants. The more premature the infant, the more likely they are to require one or more transfusions for anaemia. This becomes more likely if they are unwell at birth, particularly with neonatal sepsis.
Premature neonates become anaemic for a number of reasons:
- Less time in utero receiving iron from the mother
- Red blood cell creation cannot keep up with the rapid growth in the first few weeks
- Reduced erythropoietin levels
- Blood tests remove a significant portion of their circulating volume
Briefly describe haemoltic disease of the newborn
Haemolytic disease of the newborn is a cause haemolysis (red blood cells breaking down) and jaundice in the neonate. It is caused by incompatibility between the rhesus antigens on the surface of the red blood cells of the mother and fetus. The rhesus antigens on the red blood cells vary between individual. This is different to the ABO blood group system.
Within the rhesus group, there are many different types of antigens that can be present or absent depending on the person’s blood type. The most important antigen within the rhesus blood group system is the rhesus D antigen.
When a woman that is rhesus D negative (does not have the rhesus D antigen) becomes pregnant, we have to consider the possibility that the fetus will be rhesus D positive (has the rhesus D antigen). It is likely at some point in the pregnancy the blood from the fetus will find a way into her bloodstream. When this happens, the fetal red blood cells display the rhesus D antigen. The mother’s immune system will recognise the rhesus D antigen as foreign and produce antibodies to the rhesus D antigen. The mother has then become sensitised to rhesus D antigens.
Usually, this sensitisation process does not cause problems during the first pregnancy (unless the sensitisation happens early on, such as during antepartum haemorrhage). During subsequent pregnancies, the mothers anti-D antibodies can cross the placenta into the fetus. If that fetus is rhesus positive, these antibodies attach themselves to the red blood cells of the fetus and causes the immune system of the fetus to attack its own red blood cells. This leads to haemolysis, causing anaemia and high bilirubin levels. This leads to a condition called haemolytic disease of the newborn.
What test is used to diagnose haemolytic disease of the newborn?
A direct Coombs test (DCT) can be used to check for immune haemolytic anaemia. This will be positive in haemolytic disease of the newborn.
What is the most common cause of anaemia in children?
Iron deficiency anaemia secondary to dietary insufficiency. This is the most common cause overall.
Other than iron deficiency anaemia, what are the other causes of anaemia in children?
The key causes of anaemia in older children are:
- Iron deficiency anaemia secondary to dietary insufficiency
- This is the most common cause overall
- Blood loss, most frequently from menstruation in older girls
Rarer causes of anaemia in children include:
- Sickle cell anaemia
- Thalassaemia
- Leukaemia
- Hereditary spherocytosis
- Hereditary eliptocytosis
- Sideroblastic anaemia
Worldwide, what is a common cause of chronic anaemia?
Worldwide, a common cause of blood loss causing chronic anaemia and iron deficiency is helminth infection, with roundworms, hookworms or whipworms.
This can be very common in developing countries and those living in poverty. It is more unusual in the UK.
Treatment is with a single dose of albendazole or mebendazole.
What are the 3 categories of anaemia?
Anaemia is initially subdivided into three main categories based on the size of the red blood cell (the MCV). These have different underlying causes:
- Microcytic anaemia (low MCV indicating small RBCs)
- Normocytic anaemia (normal MCV indicating normal sized RBCs)
- Macrocytic anaemia (large MCV indicating large RBCs)
What are the causes of microcytic anaemia?
Note: TAILS
- T: thalassaemia
- A: anaemia of chronic disease
- I: iron deficiency anaemia
- L: lead poisoning
- S: sideroblastic anaemia
What are the causes of normocytic anaemia?
Note: 3As and 2Hs
There are 3 As and 2 Hs for normocytic anaemia:
- A: acute blood loss
- A: anaemia of chronic disease
- A: aplastic anaemia
- H: haemolytic anaemia
- H: hypothyroidism
What are the two types of macrocytic anaemia?
Macrocytic anaemia can be megaloblastic or normoblastic.
What is shown in the image?
Koilonychia.
What is shown in the image?
Angular chelitis can indicate iron deficiency.
What is shown in the image?
Atrophic glossitis.
