Red cells (anaemia) 2 Flashcards
What is the normal haemoglobin range for a healthy:
a) female (12-70)
b) elderly female (>70)
c) male (12-70)
d) elderly male (>70)
a) female = 120-160
b) elderly female = 108-143
c) male = 140-180
d) elderly male = 116-156
What clinical features may be seen in patients who are anaemic - related to the underlying cause
Evidence of bleeding:
- menorrhagia
- dyspepsia, PR bleeding
Symptoms of malabsorption:
- diarrhoea
- weight loss
Jaundice
Splenomegaly
Lymphadenopathy
What are the 2 main red cell indices that are used for investigating anaemia?
What are the possible morphological descriptions from these indices?
Mean cell haemoglobin (MCH)
Mean cell volume (MCV)
1) Hypochromic microcytic
2) Normochromic normocytic
3) Macrocytic
The morphological description of anaemia (from MCH, MCV measurements) gives an indication of the probable cause of the anaemia - and dictates the next step of investigation
What is the (usual) next step of investigation for:
a) hypochromic microcytic
b) normochromic normocytic
c) macrocytic
a) hypochromic microcytic = serum ferritin
* iron deficiency anaemia most common cause of h.m. anaemia*
b) normochromic normocytic = reticulocyte count
* can be elevated (haemolysing causes) or depressed (aplastic anaemia etc)*
c) macrocytic = B12/folate, bone marrow
* B12 & folate deficiency most common cause of macrocytic*
Hypochromic microcytic anaemia is identified on a blood film, so you measure serum ferritin…
What would be indicated by a:
a) Low serum ferritin
b) normal / elevated
a) Low serum ferritin:
* = iron deficiency anaemia
b) Normal or elevated serum ferritin:
- Thalassaemia
- secondary anaemia
- sideroblastic anaemia (rare)
Note that ferritin is elevated with inflammation and in some liver diseases
On the topic of iron:
a) how much is in us?
b) where is iron utilized?
c) where is iron stored?
a) 4g
b) haemoglobin and myoglobin (muscles)
c) RBCs, reticuloendothelial macrophages, liver
In what formm is dietary iron absorbed most efficiently?
In the form of haem (ie from blood)
non-haem iron absorbed less effectively
so up you, vegetarians
go learn the metabolic pathway for iron - roles of ferroportin, transferrin, ferritin, hepcidin
What are the causes of iron deficiency anaemia?
Insufficient dietary intake (veggies n vegans)
Menstruation (mennorhagia)
Dyspepsia, GI bleeding
Malabsorption - coeliac disease, gastrectomy
Increased requirement (pregnancy, puberty)
How do you correct iron deficiency anaemia?
Correct the deficiency:
- oral iron - usually sufficient
- IV iron if intolerant to oral
- transfusion rarely indicated
Correct the cause:
- diet
- ulcer therapy
- gynae interventions
- surgery
Normochromic normocytic anaemia is identified and investigation of reticulocyte count is carried out
What causes would these results indicate:
a) Increased reticulocyte count
b) Normal or low reticulocyte count
a) increased reticulocyte count:
- acute blood loss
- haemolysis
b) Normal or low reticulocyte count:
- Secondary anaemia - eg renal impairment
- hypoplasia
- marrow infiltration
What is secondary anaemia?
What morphological appearances of RBCs are seen in secondary anaemias?
Anaemias secondary to chronic diseases
70% normochromic normocytic
30% hypochromic microcytic
Another cause of normochromic normocytic anaemia is (abnormal) haemolysis
How do the values for Haemoglobin and reticulocytes change in haemolytic anaemia and why?
Accellerated RBC destruction decreases Haemoglobin
Bone marrow compensation for this = High reticulocyte count
The overall level of Hg depends on balance between production and destruction
Haemolysis can happen extravascularly and intravascularly
Which is bad?
Extravascular haemolysis occurs normally - but is pathologically elevated in certain conditions
Intravascular haemolysis is pathological and shouldnt happen
In certain haemoglobinopathies it occurs - eg in sickle cell disease
free haemoglobin in the blood is toxic
What are some congenital causes of haemolytic anaemia?
Do these cause intravascular or extravascular haemolysis?
Hereditary spherocytosis (HS)
Enzyme deficiencies (eg G6PD)
Haemoglobinopathies (eg HbSS)
These all cause increased extravascular haemolysis but conditions like sickle cell disease (HbSS) and G6PD cause some intravascular haemolysis as well
What are the acquired causes of haemolytic anaemia?
Which of these causes extravascular and intravascular haemolysis?
Extravascular:
- autoimmune haemolytic anaemia
Intravascular:
- mechanical destruction - ie leaky artificial valves
- severe infections, DIC
- pre-eclampsia (PET)
- haemolytic uraemic syndrome (HUS)
- Thrombotic thrombocytopenic purpura (TTP)
Immune - extravascular. Non-immune - intravascular
How do you test for immune causes of haemolytic anaemia
Direct antiglobulin test - aka Coomb’s test
this detects any antibodies or compliment on RBC membrane
Contains either:
- anti-human IgG
- anti-compliment
If positive (ie immune haemolytic anaemia) then reagant causes agglutination in vitro
What appearance (shape) do RBCs have on blood films in immune haemolytic anaemia?
Why?
Spherical appearance - spherocytes
This is because:
1) RBCs with auto-antibodies attached enter spleen
2) Spleen recognises antibodies and is like nah not tonight mate - so removes the antibodies and a wee bit of RBC membrane
3) Damaged RBC membrane causes them to take up this spherical shape
On a blood film, what would be the appearance of RBCs seen with intravascular haemolysis?
Schistocytes
Fragmented RBCs sort of all mashed up
Summarise what investigations would tell if you if a patient was haemolysing abnormally?
FBC, Reticulocyte count, blood film
High bilirubin
High LDH
Low haptoglobin
What tests would you do to determine the mechanism causing haemolytic anaemia?
History and examination
Blood film
Coomb’s test (DAT)
Urine for haemosiderin/urinobilinogen
Describe the management of haemolytic anaemia
Support marrow function:
- Folic acid - people with H anaemia use up lots of folate
Correct the cause:
- Immunosuppression if autoimmune:
- steroids
- treat causes such as CLL, lymphoma etc
- Remove site of RBC destruction
- splenectomy
- Treat sepsis, leaky valves, malignancy etc
Transfusion if required
What is the primary investigation for someone who has macrocytic anaemia and why?
B12 / Folate assay
Deficiency in these is the most common cause of macrocytic anaemia. Macrocytic anaemia caused by this are called Megaloblastic
If a patient has macrocytic anaemia that is non-megaloblastic, what investigations are indicated and what are the potential causes?
Blood film
Bone marrow
Potential causes - myelodysplasia, marrow infiltration, certain drugs (methotrexate etc)
