Common causes of anaemia and thrombocytopenia Flashcards
(36 cards)
What are the main causes of anaemia (other than blood loss)?
- B12/folate def
- Chronic disease-
Haemolysis - Alcohol, drugs, toxins
- Renal impairement - EPO
- Haematological/marrow disorders e.g. malignant, haemoglopathies, aplasia, congenita
What conditions are associated with macrocytic, normocytic and microcytic RBC?
Macro - B12/folate def, marrow damage (alcohol/toxin, marrow disease), haemolysis (new ones are bigger than old ones)
Normo - chronic disease/inflammatiojn
Micro - Hb-opathies, iron def
Why is iron deficiency so common?
Iron is not absorbed easily (at duodenum) - mostly recycled
How is iron stored in in the body?
In ferritin
How is iron deficiency diagnosed?
LOW FERRITIN LEVELS
- low MCV, hypochromic (small, pale)
What causes iron deficiency?
Blood loss e.g. menstrual loss/periods, cancer, ulcer, GI etc
Increased demand e.g. growth/pregnancy
Malabsorption - diet/malabsorption
How is iron deficiency treated (best way!)?
IV iron
What is the cause of macrocytic RBCs?
Impaired DNA synthesis
Why does folate/B12 deficiency cause macrocytic RBCs?
Folate involved in purine/pyridamine synthesis
B12 required for folate synthesis
therefore, deficiency causes DNA synthesis impairment
How is B12 absorbed? What is the cause of B12 deficiency?
Parietal cells in stomach produce intrinsic factor which binds to B12
B12-intrinsic factor - absorbed in terminal ileum by specific factors
NOT cause by malnutrition, deficiency somewhere in this pathway
What are the main causes of B12 deficiency?
Stomach - pernicious anaemia , gastrectomy
Terminal ileum - churns disease, terminal ileum resection
How is folate deficiency caused?
- Malnutrition
- Increased demand e.g. pregnancy, haemolysis
- Malabsorption/small bowel disease
- Alcohol/toxins/ITU
What are the common features of B12/folate deficiency?
- Megablastic anaemia
- Pancytopenia (low RBCs, WBCs, platelets)
- mild jaundice
- anorexia/weight loss
- sterility
What are lab features of B12 and folate deficiency?
- Blood count and film
- Bilirubin and LDH - haemolysis (do not last as long!)
- Antibodies - pernicious anaemia
What is pernicious anaemia?
Autoimmune condition where body produces antibodies against parietal cells.
Intrinsic factor not produced so doesn’t bind to B12.
B12 not absorbed by terminal ileum - therefore, B12 deficiency
What is the over condition associated with severe B12 deficiency?
Subacute combined degeneration of the cord
Demyelination of dorsal and lateral columns
Peripheral nerve damage
Reversible cause of demenetion
What is the treatment of B12 and folate deficiency?
B12 and folate infused (muscularly) until B12 deficiency excluded
DO NOT GIVE folate individually - can exacerbate B12 induced neuropathy
What are the main causes of haemolysis?
- Things wrong inside RBC
- Things wrong with RBC membrane
- Things wrong external to RBC
What intrinsic RBC factors could cause haemolysis?
Sickle cell disease Enzyme deficiency (G6PD)
What RBC membrane factors could cause haemolytic disease?
Hereditary sphereocytosis
What external RBC factors could cause haemolysis?
- Antibodies (autoimmune -haemolytic anaemia - COOMB’S TEST)
- Vasculitis
- Heart valves (mechanical)
- Toxins/drugs
What are the diagnostic markers for haemolysis?
- Anaemia (?)
- Macrocytic RBCs (increased reticulocytes)
- RBC film - fragments, spherocytes
- Raised Bilirubin/LDH
What is the normally MCV for chronic disease?
Normocytic
How is anaemia in chronic disease usually caused?
Inflammatory diseases reduces iron absorption and iron metabolism
Poor erthropoetin response
Blunted marrow response
