Anaemia Flashcards
Describe the process of erythropoiesis
Erythropoietin release is stimulated by hypoxia
90% from the kidneys, rest from liver
This increases the number of erythroid progenitor cells, which differentiate and produce haemoglobin.
Describe the structure of haemoglobin. In adults? Fetus?
Tetramer with 2 global chains - each has a haemorrhage group containing iron, which binds oxygen.
2 configurations:
Relaxed state which has a high affinitiy for oxygen - when high PO2 or CO present, and Tense state which has a low affinity for oxygen -when there is higher PCO2 - thus it is harder for oxygen to bind initially, when pO2 is low - oxygen is dissociated (at tissues). As oxygen binds it becomes easier for O2 to bind as Hb becomes relaxed. So Hb is highly saturated with O2 in the lungs and less so at the tissues
HbA - 2 alpha globin and two beta global
HbF has two alpha and two gamma - higher affinity for oxygen
What are the function of haemoglobin and myoglobin? Iron significance?
Transport of oxygen and CO2 in the blood two and from the tissues
Myoglobin facilitates the storage of O2 in the muscles
Iron is an essential part of haemoglobin, myoglobin and cytochromes which are important for the electron transport chain.
How can anaemia occur?
Mutations in genes for globin proteins leading to haemolytic anaemia - cells don’t survive 120 days: talassaemia sickle cell disease
Lack or iron : IDA, anaemia of chronic disease
Deficiency of building blocks for DNA synthesis: B12, folate
Red cell membrane problems - haemolytic anaemia
MEtabolic dysfunction - G6PD deficiency
Removal of damaged or antibody coated cells - splenomegaly in liver disease, malaria, malignancy
Blood loss - menorrhagia, GI bleed
Bone marrow failure
What are physiological adaptations to anaemia?
Increased CO - SV tachycardia
Shift in Hb oxygen dissociation curve - 2,3 DPG in RBCs increases with anaemia (and altitude). It shifts the Hb O2 dissociation curve to the right meaning O2 is given up more readily at the tissues. This also occurs in more acidic (Bohr shift) and higher temperature tissues due to more O2 required in metabolically active tissues.
Increased erythropoiesis
What are the symptoms of anaemia?
Shortness of breath Weakness Lethargy Palpitations Headaches Angina, HF, claudication, confusion
What are signs of anaemia
Pallor Tachycardia Systolic flow murmur Heart failure Koionychia - spooning of nails - IDA Glossitis - B12 deficiency Thalassaemia Leg ulceration Angular stomatitis
What can you check to evaluate anaemia?
Reticulocyte count (immature large red blood cells) Indicate whether anaemia is due to reduced production - bone marrow failure or deficiency (low reticulocyte) or from increased removal - bleeding or destruction (raised reticulocyte)
IF white cell and platelets are low - bone marrow failure
What are causes of low reiculocyte anaemia?
Microcytic (low mean cell volume)
Normocytic (normal mean cell volume)
Macrocytic (high mean cell volume)
What are causes of reticulocytosis anaemia?
Bleeding
Splenic sequestration (splenomegaly - liver cirrhosis)
Haemolysis
- immune, mechanical
What are features of B12 deficiency? What is subacute combined degeneration of the spinal cord? Features?
Symptoms of anaemia
Lemon tinge - jaundice due to haemolytic and pallor - anaemia
Glossitis
Angular stomatitis
Irritability, depression, psychosis
Paraesthesiae, peripheral neuropathy
Combined perisperhal sensory neuropathy with upper and lower motor neurone signs due to B12 deficiency.
Extensor plantar reflex
Absent knee jerk
Absent ankle jerk
Symmterical
Dorsal column loss and corticsspinal tract loss. Spinothalamic tract preserved
