Anaemia and Microcytic anemia Flashcards
Define anaemia
- reduced total RED CELL mass
What are the markers for anaemia?
- HEMATOCRIT
- Hb conc.
When are you considered anaemic?
- man: <130 g/L (Hct: 0.38-0.52)
- WOMAN: <120g/L (Hct: 0.37- 0.47)
What is the role of the macrophage to the red cell? -
- provides iron to the RBC
How to measure Hb conc. using the spectrophotometric method?
- lyse the red cells and create a Hb solution
- stabilise the Hb molecules with a CHELATING agent
- measure the OPTICAL density at 540nm *more OD = more Hb)
- —conc is calculated against the KNOWN standard
How to measure hematocrit?
- ratio/ % of the WHOLE blood that is RED when the sample settles
- MODERN machines calculate by ADDING the calculated volume of the red cells
When are Hb/Hct NOT a good marker of anaemia?
when they are not in a steady state
- those who have a MASSIVE, RAPID blood loss
- —-Hb will appear the SAME amount as prior the blood loss (untilplasma expansion) - hemodilution (raised plasma volume will cause a proportionate reduction in Hb)
How does the bone marrow respond in anaemia?
What are they >
- rise in RETICULOCYTES
- —they are red cells that have JUST left the BONE marrow
What do reticulocytes appear as?
- larger than avg red cells
- purple appearance (d.t RNA reminence)
- POLYCHROMATIC in blood film
- —remnants of protein making machinery
How long does it take the reticulocytes to appear in the blood smear?
- a few days
What do automated analysers tell us about red cells?
- cell size (MCV)
- # OF RED CELLS (CONC)
- Hb conc.
What are the fts of automated analysers?
light scattering properties
- rapid
- reproducible
2 Main pathophysiological paths of anaemia?
How does the retic counts differ from one another?
- decr. prodn (LOW retic count)
- incr. destruct. or LOSS of red cells (HIGH retic. count)
What is another name for decr. prodn?
- Hypoproliferative (reduced rate of erythropoiesis)
- maturation abnormality (ineffective erythropoiesis)
What causes incr. destr. of red cells?
- bleeding
- hemolysis
Where may the maturation abnormality be present?
- NUCLEAR defects (impaired cell division)
- CYTOPLASMIC DEFECTS (impaired hemoglobinisation)
If MCV is LOW, what may it indicate?
- probable issue with hemoglobinisation
IF MCV is HIGH, what may it indicate?
- issue with MATURATION
What does hypochromic, microcytic anaemia indicate?
- deficient Hb synthesis
- cytoplasmic deficit
What causes haem deficiency?
- LACK of IRON for erythropoiesis (d.t chronic disease/ iron def.)
- Problems with Porphyrin synthesis (V.RARE) (LEAD poisoning and pyridoxine responsive anaemia)
- Congenital sideroblastic anemia
What is iron needed for?
- ion transport (needed for ATP prodn in the Mitochondria)
- Oxygen transport (Hb, myoglobin)
How many mg of iron is absorbed in a day?
1 mg
Where is iron stored?
in a protein called ferritin IN THE LIVER
Where is the circulating iron bound to an dwhere is ti transported to ?
Transferrin— transferred to the BONE marrow macrophages that FEED it to the red cell precursors
WHen is transferrin saturation reduced?
And Incr.?
- in iron def.
- ## reduced in ANAEMIA of chronic disease (USE ferritin conc. instead)
- INCREASED in genetic hemachromatosis
What does trasnferrin do?
- transports iron from DONOR tissues (macrophages/ intestinal cells and hepatocytes) to tissues expressing transferrin receptors (erythroid marrow)
When does ferritin drop? -
- WHEN there is NOT much of stored iron —-iron def.
How much iron can ferritin store? -
up to 4000 ferric ions
When may one have ABSOLUTE iron deficiency?
- those on a VEG diet
normal in girls
What causes iron deficienct?
- GI blood loss (esp. in men )
- not absorbing enough (MALABSORPTION—COELIAC DISEASE and ACHLORHYDRIA)
What causes chronic blood loss
Menorrhagia
Gastrointestinal
(Tumours/Ulcers/Non-steroidal anti-inflammatory agents)
Haematuria
Epithelial changes in microcytic anemia (iron def.)?
- skin changes
- koilonychia
When is one considered to have menorrhagie?
- those with menses blood loss >60ml
- —i.e >30mg iron loss in a month
What is the normal blood loss in menses?
- 30-40ml/month
What is calculated in a red cell indices?
- Hematocrit
- mean cell HB
- Mean cell Hb Conc.
Where is Hb synthesized? What is required?
in the cytoplasm
—–results in SMALL cells
- globins, Haeme (porhyrin and iron -Fe2+)
What occurs as a result of LOW raw material of Hb?
- results in SMALL red cells with a LOW hb content
microcytic and hypochromic
What causes globin deficiency>
- thalassaemia
Why is iron toxic for it to freely float around in the body?
- generates FREE radicals ‘
- therefore needs a safe transport system
Describe the structure of an adult Hb.
4 globin sub-units—each containing a SINGLE haem molecule
- –a haem gr. contains a SINGLE FE2+ ion
- –each haem gr can bind one Oxygen molecule
So where is iron found and thus could be tested?
FUNCTIONAL iron (Hb) Transported iron ( serum iron/ transferrin/ transferrin saturation) Storage Iron (serum ferritin)
How many binding sites for iron atoms on transferrin?
2 sites
What is Ferritin?
What does its presence in the blood suggest>
- large intracellular protein
- —-tiny amount of ferritin in serum =intracellular ferritin synthesis in resp. to iron status of the host.
What is a indirect measure of iron storage?
- serum ferritin
SO iron deficiency could be a combination of _______ and ______
ANAEMIA
REDUCED storage iron (FERRITIN)
Why does poor acid prodn in the stomach affect iron absorption? Name 2 conditions where acid prodn by the stomach is reduced.
Acid is needed to convert iron to its ferrous state (Fe2+)
- post gastrectomy
- use of PPIs
How to differentiate mild thalassemia from iron def. anaemia?
- RDW is NORMAL in thalassemia (genetic defect present in ALL cells)
- —wider in iron def. anaemia (some cells are able to get iron; others are not)
