T7-L8: Common causes of Anaemia and Thrombocytopenia Flashcards
Give causes of anaemia.
- Blood loss
- Haemolytic deficiencies such as iron, folate and B12
- Alcohol, drugs and toxins
- Renal impairment
- Primary haematological/marrow disorders
- Secondary to chronic disease
- Haemeolysis
How is iron balance in the body achieved?
- We do not absolve a lot of the iron we eat (only 7%)
- We do not excrete iron
- We do not have the capability to increase iron uptake
- Iron is taken up in the duodenum (and less is in the the jejunum) and transported to the ileum
- It is stored in ferritin/haemosiderin
- Iron uptake is controlled at the level of the gut mucosa
What lab tests can we use to establish low iron?
- Ferritin levels, if levels are low = diagnostic of iron deficiency
- FBC, MCV (iron deficine anaemia tends to be microcytic and so will be reduced) and blood film
- % of hypo chromic cells
- Serum iron/TIBC (but serum iron varies all the time)
For Iron deficiency give:
(a) Appearance on a blood film
(b) Causes
(c) Treatment
(a) Microcytic
(b) Blood loss, Reduced absorption at the gut e.g. celiac disease, heavy mensuration, pregnancy and growth, malnutrition in younger patients. In older patients consider malignancy, ulcers, diverticulitis, surgeries etc.
(c) Iron replacement
For megablastic anaemia:
(a) Appearance on a blood film
(b) Causes
(c) Treatment
(a) Enlarged RBC
(b) The most common causes are Folate and B12 deficiency. Other causes includes alcohol, drugs, haematological malignancy and congenital abnormalities (e..g Transcobalamin deficiency).
How is B12 absorbed? What are causes of deficiency?
Gastric parietal cell produce intrinsic factor (IF). Intrinsic factor and B12 are absorbed together in the ileum.
Causes of deficiency:
- Issues with IF production due to gastric issues
- issues with absorption e.g. Crohns, jejunal diverticulitis and fish tapeworm
- Nutritional - e.g. in vegans as B12 is only found inanimate products
- Perinicious anemia
- Subacute combined degeneration of the cord
What are causes of folic acid deficiency?
- Dietary/malnourishment
- Malabsorption
- Increase usage e.g. pregnancy, haemolysis, inflammatory disorders
- Drugs/Alcohol
- UTI
What are features of B12 or folate deficiency?
- Megaloblastic anaemia
- Pancytopenia can result if severe
- Mild jaundice - due to RBC breakdown
- Glossitis/angular stomatitis
- Anorexia
- Sterility
- Can detected on a FBC and film
- May show elevated Bilirubin and LDH - haemolysis
- Can also detect antibodies affecting B12 absorption as in Pernicious anaemia
- GI investigations must also be done such as Crohn’s, malabsorption and blind loop
What is the treatment for folic acid or B12 deficiency?
- B12 subcutaneous injection very 3 months
- Folate tablet 5mg daily to build stores
- If very deficiency - when you start replacing the vitamins there is such a rush of new cells being produced, potassium may be depleted. This can lead to cardiac arrest. This is only on the severe end.
You may need to replace therefore potassium and iron initially
How do we test for haemolysis?
Test - presence of haemolysis t:
- Anaemia (may not if compensated)
- High MCV. Macrocytic - reticulocytes being chucked out
- Blood film (fragments, spherocytes, sickle cell, reticulocytes)
- High reticulocytes
- Raised bilirubin, LDH (lactase dehydrogenase)
- Low haptopglobins - bind haemoglobin
- Urinary hemosiderin - release of haemoglobin that is not being used produces this by-product
How does anaemia of chronic disease normally present?
- Normally with normocytic anaemia
- Usually present with no other cause of anaemia
- Pateints would have a suitable medical history
- Often have raised inflammatory markers - ESR, CRP, PV etc.
- Often have normal/raised ferratin and low serum iron - iron stores are okay but the iron is not being released. There is a block of utilisation
- Normal % saturation transferrin
What is the role of Hepcidin in anaemia of chronic disease?
Anaemia results due to changes in cytokines in an inflammatory ill patient. Cytokine pattern inhibits RC production. The key enzyme is Hepcidin - Regulator of iron absorption and release from macrophages. Hepcidin goes up in an inflammatory state - it stops iron release from stores and stops iron uptake from the gut.
What are causes of thrombocytopenia?
- Drugs, alcohol, toxins
- ITP (sometimes associated with lymphoma/CLL/HIV)
Other autoimmune diseases - Liver disease and / or hypersplenism (platelets get caught in the enlarged spleen)
- Pregnancy (physiological and a range of complications)
- Haematological / marrow diseases
- Infections acute or otherwise e.g. Acute sepsis / HIV / other viral infections (EBV and many others)
- Disseminated Intravascular Coagulation (DIC)
- Range of congenital conditions
There are also many others.
What is ITP?
ITP can cause excessive bruising and bleeding. An unusually low level of platelets, or thrombocytes, in the blood results in ITP. Usually of idiopathic cause. It is quite a common condition. We see a split between children and adults. In children it tends to be quite severe and comes after a viral infection and tends to be self-limiting. In adults however it is less likely to completely self-limit - tends to go onto be common. There is no precipitating condition.
Steroids are very effective in those that need it. IV immunoglobin can be used short term. Some need more long term immunosuppression or splenectomy.
What is TTP?
Thrombotic Thrombocytopenia Purpura
There are antibodies against vWF (ADAMTS-13). Platelets are sensitive to vWF. This can lead to platelet destruction and endothelial damage.
Patients present with widespread vasculitis, thrombosis and develop DIC with no platelets.
