Nutritional Anaemia 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
Describe the structure of haemoglobin in RBCs
- One iron group per heme.
- one heme group per subunit
- 4 subunits make up oner molecule of haemoglobin
What is needed for normal erythropoiesis to take place
- Vitamin B12
- Folic acid
- Iron
- Vitamins
- Cytokines
- Healthy bone marrow environment
why may a patient be anaemic
- Failure of production
- Ineffective erythropoiesis
- Decreased survival
How would we investigate low Hb levels
Do a full blood count
What can we see about the mean cell volume in a full blood count
- Microcytic RBC
- Normocytic RBC
- Macrocytic RBC
What can cause microcytic anaemia
- Iron deficiency
- Thalassamia
- Anaemia of chronic disease
What can cause Normocytic anaemia
- Anaemia chronic disease
- Aplastic anaemia
- Chronic renal failure
- Bone marrow infiltratrion
- Sickle cell disease
What can cause macrocytic anaemia
- B12 deficiency
- Folate deficiency
- Myelodysplasia
- Alcohol induced
- Drug induces
- Liver disease
- Myxoedema
Define nutritional anaemia
Anaemia caused by lack of essential ingredients that the body acquires from
food sources
How is iron used in the body
- Essential for O₂ transport
- Most abundant trace element in body
- Daily requirement for iron for erythropoeisis varies depending on gender and physiolgical needs
How is iron distributed in adults
- The duodenum takes in 1-2gm per day via the diet
- Plasma transferrin (3mg)
- Bone marrow (300mg)
- Muscle myoglobin (300mg)
- Liver (1000mg)
- Circulating erythrocytes (1800mg)
- Reticuloendothelial macrophages (600mg)
- Iron loss 1-2mg per day
How is Iron metabolised
- Ferric states (3+) and Ferrous states (2+)
- Most iron is in the body as circulating Hb
- Remainder as storage and transport proteins; ferritin and haemosiderin
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
The amount absorbed depends on type ingested: red meat> than non-heme
What is the role of hepcidin in the regulation of iron
Hepcidin causes ferroportin internalisation and degradation, thereby decreasing iron transfer into blood plasma from the duodenum
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 does the laboratory iron tests tell us
- Serum Fe: Hugely variable during the day
- Ferritin: Primary storage protein & providing reserve, Water soluble
- Transferrin Saturation: Ratio of serum iron and total iron binding capacity – revealing %age of transferrin binding sites that have been occupied by iron
- Transferrin: Made by liver, Production inversely proportional to Fe stores. Vital for Fe transport.
- Total Iron Binding Capacity: Measurement of the capacity of transferrin to bind iron It is an indirect measurement of transferrin
What do the laboratory tests show for iron deficient anaemia
- Ferritin: LOW
- TF Saturation: LOW
- TIBC: HIGH
- Serum Iron: LOW/NORMAL
What are the causes for iron deficiency
- Poor diet
- Malabsorption
- Increased physiological needs
- Blood loss
- GI tract loss
- Parasites
What are some symptoms and signs of iron deficient anaemia?
Symptoms:
- Fatigue
- Lethargy
- Dizziness
Signs:
- Pallor of mucous membranes
- Bounding pulse
- Systolic flow murmurs
- Smooth tongue, koilonchias
What are the causes of megaloblastic: low reticulocyte count
- Vitamin B12/Folic acid deficiency
- Drug-related (interference with B12/FA metabolism)
What are the causes of nonmegaloblastic low reticulocyte count
- Alcoholism
- Hypothyroidism
- Liver disease
- Myelodysplastic syndromes
- Reticulocytosis (haemolysis)
What is B12 and folic used for
- Both are important for the final maturation of RBC and for the synthesis of DNA
- Both needed for thymidine triphosphate synthesis
What is the difference between megaloblastic and non-megaloblastic
Megaloblastic changes in blood cells are seen in B12 and Folic Acid deficiency. They are characterized on the peripheral smear by macroovalocytes and hypersegmented neutrophils.
What can cause folate deficiency
- Increased demand
- Decreased intake
- Decreased absorption
how does increased demand cause folate deficiency
- Pregnancy/Breastfeeding
- Infancy and growth spurt
- Haemolysis & rapid cell turnover
- Disseminated cancer
- Urinary losses e.g: heart failure
How does a decreased intake lead to folate deficiency
- Poor diet
- Elderly: eat less
- Chronic alcohol intake
How does decreased absorption lead to folate deficiency
- Medication (folate antagonist)
- Jejunal resection
- Tropical sprue
How is Vitamin B12 absorbed in the ileum
- Requires the presence of Intrinsic Factor for absorption in terminal ileum
- IF made in Parietal Cells in the stomach Transcobalamin II and Transcobalamin I transport vitB12 to the tissue
What are some causes of B12 deficiency
- Impaired absorption
- Decreased intake
- Congenital causes
- Increased requirements
- Medication
what can cause impaired absorption of B12
- Pernicious anaemia
- Gastrectomy or ileal resection
- Zollinger-ellison syndrome
- Parasites
What can cause decreased intake of B12
- Malnutrition
- Vegan diet
What congenital causes led to B12 deficiency
- Intrinsic factor receptor deficiency
- Cobalamin mutation C-G-1 gene
How can increased requirements cause b12 deficiency
- Haemolysis
- HIV
- Pregnancy
- Growth spurts
What medications can cause b12 deficiency
- Alcohol
- NO
- PPI, H2 antagonists
- Metformin
What are the clinical consequences?
Brain: Cognition, depression, psychosis
Neurology: myelopathy, sensory changes, ataxia, spasticity
Infertility
Cardiac cardiomyopathy
Tongue: Glossitis, taste impairment
Blood: Pancytopenia
What is pernicious anaemia
- Autoimmune disorder
- Lack of IF
- Lack of B12 absorption
- Gastric Parietal cell antibodies IF antibodies
What are the treatments for nutritional anaemias?
- Treat the underlying cause
- Iron – diet, oral, parenteral iron supplementation, stopping the bleeding
- Folic Acid – oral supplements
- B12 – oral vs intramuscular treatment
