Nutritional Anaemias Flashcards
What is anaemia?
“Anaemia is a condition in which the number of red blood cells (and consequently their oxygen-carrying capacity) is insufficient to meet the body’s physiologic needs.”
Insufficient oxygen carrying capacity is due to reduced haemoglobin concentration as seen with insufficient RBC
What are the elements that form blood?
The formed elements of blood are: - Red blood cells - Platelets - White blood cells including: · Monocytes · Lymphocytes · Eosinophils · Basophils · Neutrophils
What does the maturation of red blood cells require (7)?
- Vitamin B12 and folic acid
- DNA synthesis
- Iron
- Haemoglobin synthesis
- Vitamins
- Cytokines
- Healthy bone marrow environment
What are the different mechanisms of action of anaemia?
Failure of Production:
- Hypoproliferation- so not enough of the required ‘ingredients’
- Reticulocytopenic- lots baby red blood cells circulating because the bone marrow is overcompensating
Ineffective Erythropoiesis- right ingredients, wrong instructions
Decreased Survival
- Blood loss, haemolysis, reticulocytosis
What are the different causes of anaemia?
Microcytic: - Iron deficiency (heme deficiency) - Thalassemia (globin deficiency) - Anaemia of chronic disease Normocytic: - Anaemia Chronic disease - Aplastic anaemia - Chronic renal failure - Bone marrow infiltration - Sickle cell disease Macrocytic: - B12 and folate deficiency - Myelodysplasia - Alcohol induced - Drug induced - Liver disease - Myxoedema
What are nutritional anaemias?
Anaemia caused by lack of essential ingredients that the body acquires from food sources
Iron deficiency
Vitamin B12 deficiency
Folate deficiency
What are the stable forms of iron in the body?
> 1 stable form of iron:
Ferric states (3+) and Ferrous states (2+)
Most iron is in body as circulating Hb
- Hb: 4 haem groups, 4 globin chains able to bind 4 O2
Remainder as storage and transport proteins
- ferritin and haemosiderin
- Found in cells of liver, spleen and bone marrow
How is iron absorbed in the body?
Regulated by GI mucosal cells and hepcidin
Duodenum & proximal jejunum
Via ferroportin receptors on enterocytes
Transferred into plasma and binds to transferrin
Amount absorbed depends on type ingested
Other foods, GI acidity, state of iron storage levels and bone marrow activity affect absorption
How does hepcidin regulate iron levels?
The iron-regulatory hormone hepcidin and its receptor and iron channel ferroportin control the dietary absorption, storage, and tissue distribution of iron…
Hepcidin causes ferroportin internalization and degradation, thereby decreasing iron transfer into blood plasma from the duodenum, from macrophages involved in recycling senescent erythrocytes, and from iron-storing hepatocytes.
Hepcidin is feedback regulated by iron concentrations in plasma and the liver and by erythropoietic demand for iron.
How is iron transported and stored?
Iron transported from enterocytes and then either into plasma or if excess iron stored as ferritin
In plasma: attaches to transferrin
and then transported to bone marrow binds to transferrin receptors on RBC precursors
A state of iron deficiency will see reduced ferritin stores and then increased transferrin
What do iron deficiency lab results look like?
Low ferritin
Low TF saturation
High TIBC
Low to normal serum iron
What are the iron deficiency investigations?
FBC: Hb, MCV (mean cell volume), MCH (mean cell haemoglobin), Reticulocyte count
Iron Studies: Ferritin, Transferrin Saturation
Blood film
BMAT (bone marrow biopsy) and Iron stores in the olden days
What are the stages in the development of IDA?
Before anaemia develops, iron deficiency occurs in several stages.
Serum ferritin is the most sensitive laboratory indicators of mild iron deficiency. Stainable iron in tissue stores is equally sensitive, but is not performed in clinical practice.
The percentage saturation of transferrin with iron and free erythrocyte protoporphyrin values do not become abnormal until tissue stores are depleted of iron.
A decrease in the haemoglobin concentration occurs when iron is unavailable for haem synthesis.
MCV and MCH do not become abnormal for several months after tissue stores are depleted of iron.
What are the IDA signs and symptoms?
Symptoms - fatigue, lethargy, and dizziness Signs - pallor of mucous membranes, - Bounding pulse, - systolic flow murmurs, - Smooth tongue, koilonychias
What are B12 and folate deficiencies?
Both have very similar laboratory finding and clinical symptoms
Can be found together or as isolated pathologies
Causes macrocytic Anaemia
Low Hb and high MCV with normal MCHC
