Week 1 - Day 1 Tutorial - Concepts In Haematology -Iron deificiency anaemia and G6PD deficiency Flashcards
Cell count may be low due to: Increased destruction OR Reduced production OR Redistribution What can cause a cell count to be high?
Increased production in response to stimulus Increased production with no stimulus intrinsic (malignancy) or Redistribution
When cytosis or philia is the suffix of the word - this generally mean excess eg neutrophilia means excess neutrophils. What is the difference between thrombocytosis and thrombophiia? Penia generally means reduced - give example?
Thrombocytosis - excess platelets Thrombophilia - excess clotting Penia - neutropenia -decreased neutrophil count Lecuopeia - decrease WBC count, erythropenia - decreased RBC count
What is the he maintenance by an organism of a constant internal environment? This process keeps production balanced with destruction - the bone marrow uses this to remain in balance
This would be homeostasis
What is the overarching term for the erythroid producing part of the bone marrow ?
This would be the erythron
What is the feedback system to stimulate erythropoiesis: What hormone is produced and in response to what? Where is this hormone released from?
In response to hypoxia the interstitial fibroblasts near to the peritubular capillaries and the proximal convoluted tubule of the kidney will produce EPO (erythropoeitin) - this stimulates erythropoiesis
Hypoxia = anaemia (or at least relative anaemia) Results in increased production of the hormone erythropoietin Erythropoietin stimulates cell division of red cell precursors and recruits more cells to red cell production in the marrow What else does eryhtropoetin stimulate the division of? it usually can go up if somebody is eg iron deficiency anaemia
EPO also stimulates cell division of a primitive cell that is a precursor to both red blood cells and platelets therefore can see a rise in the platelet level when somebody is aneamic and therefore hypoxic
If you are hypoxic because your lungs don’t work, your going to have a high EPO regardless of the haemoglobin level Hypoxia is the relative lack of oxygen, not the lack of red blood cells The result is erythroid hyperplasia ie more machinery to produce red cells Whee is the hypoxia sensor again and what is produced in response to hypoxia? What 2things are important for nuclear development of RBC?
HYpxoia sensor is in the kidneys The interstitial fibroblasts in the kidney (situated near the peritubular capillaries and the proximal convoluted tubule produce erythropoietin to stimulate the production of red blood cells in the bone marrow B12 and folate are very important for the nuclear division of the RBC
Describe the absorption process of vitaminB12 (cobalamin) from the diet? WHat are the receptors that the vitB12/? complex binds to where? to be absorbed?
Once ingested the vitamin B12 enters the stomach In response to food, the gastric parietal cells in the gastric mucosa secretes HCl and intrinsic factor .The B12 is unable to bind to the intrinsic factor in the acidic conditions and therefore requires the pancreatic enzymes which come into the proximal small bowel (duodenum) which makes the environment alkaline and therefore the intrinsic factor and vitB12 bind . The complex binds to cubilin receptors in the distal small bowel (terminal ileum) to be absorbed
- What do the gastric parietal cells secrete?
- What do the G cells secrete?
- What do the chief cells secrete?
- What do the D cells secrete?
- What do the goblet cell secrete?
- Gastric parietal cells -hydrochloric acid and intrinsic factor
- G cells - gastrin - promotes intrinsic factor to secrete more
- Chief cells - pepsinogen
- D cells - somatostatin - inhibits HCl secretion
- Goblet cells secrete - mucous
34yr old woman with history of coeliac disease. As a result she is not absorbing iron from proximal gut. What would happen in response to this?
In response, to the iron deficiency, there would be an associated hypoxia due to anaemia (the cells dont have the raw materials to make Hb therefore haemaglobin concentration falls). The hypoxia would be sensed by the kidneys and EPO would cause erythroid hyperplasia as an attempt to prevent the anaemia. As there are no raw materials, still would have a low Hb count.
Describe the bloods in iron deficiency anaemia?
Hb - decreased MCV - decreased Platelets - increased Ferritin - low TIBC (total iron binding capacity - transferrin) - high Microcytic hypochromic anaemia
What is a low MCV classified as? What is a high MCV classified as? What is the normal MCV range?
Low MCV - volume less than 80 femtolitres High MCV - volume greater than 100femtolitres Normal MCV - 80-100femtolitres (femto is x10-15)
24yr old woman presents with acute blood loss following the delivery of her third child. Bleeding is rapidly controlled by a combination of local pressure and oxytocin but she has lost approximately a litre of blood in a very short period of time. Hb rapidly falls * What immediate physiological changes will be observed clinically? * How will she respond to the anaemia to restore homeostasis? * Any potential limitations to restoring homeostasis?
Hypotension, tachycardic, tachpnoeic, peripheral shutdown (perfuse central organs) RAAS system will try to restore the total blood volume EPO will be released from kidneys to stimulate erythropoeisis - increase in circulating reticuloytes after 7 days Potential limitations - patient remains iron deficient, Loss of raw materials eg iron, vitB12, folate
A 3 year old boy with glucose-6-phosphate dehydrogenase deficiency is anaemic. He has normal levels of the necessary materials to make haemoglobin but due to the deficiency in G6PD his red cells cannot withstand the oxidative stresses of normal life and so have a vastly reduced survival (30 days compared to the usual 120 days) in the circulation. What are the consequences of this reduced red cell survival? Will he necessarily be anaemic?
Due to G6PD deficiency, red cells cannot withstand the oxidative stresses f normal life (no glutathionine) and therefore the red cells are damaged and die very young Not necessarily be anaemic due to compensatory mechanisms - EPO increased and a reticulocytosis He will need more B12 and folate – potential for folate being a limiting factor here
When are patients with G6pd deficiency likely to become anaemic?
Likely to become anaemic in states of oxidative stress eg infection as the free radicals will destroy too many red blood cells to compensate for - haemolytic anaemia This deficiency can cause hemolytic anemia, usually after exposure to certain medications, foods, or even infections.
