macrocytic anaemia Flashcards
compare checking ferrtin levels with checking iron levels?
Checking ferritin level is better than checking iron level because feritin is IC and iron is EC so ion level would fluctuate and can even depend on the day-> ferritin gives a much better general view
however feritin is an acute phase protein-> HIGH IN INFLAMMATION-> not reliable if CRP is high
define macrocytic anaemia?
Anaemia associated with a high MCV of erythrocytes (>100 fl in adults)
usually result of abnormal haemopoeisis -> red cell precursors continue to make Hb an dother cellular proteins but fail to divide normally
what is meant by megaloblastic?
delay in maturation of nucleus-> cytoplasm continues to mature and cell continues to grow- unusually large and structurally abnormal, immature cells
OVAL MACROCYTES
what are the causes of megaloblastic anaemia?
B12 or folate deficiency -> needed for DNA production and nuclear maturation
Drugs
what are the causes of b12 deficiency?
Reduced absorption (e.g. post-gastrectomy, pernicious anaemia – autoimmune condition causing severe lack of IF, terminal ileal/small bowel resection or disease)
Reduced intake (vegans)
Abnormal metabolism (congenital transcobalamin II deficiency)
what are the causes of folate deficiency?
Reduced intake (alcoholics, elderly, anorexia)
Increased demand (pregnancy, lactation, malignancy, chronic inflammation)
Reduced absorption (coeliac, tropical sprue)
Jejunal disease (e.g. coeliac disease)
Drugs (e.g. phenytoin)
What drugs cause megaloblastic anaemia?
Methotrexate (dihydrofolate reductase inhibitor)
Hydroxyurea
Azathioprine
Zidovudine
what are the causes of non- megaloblastic macrocytic anaemia?
Alcohol excess or Liver disease – ROUND macrocytes
Myelodysplasia
Multiple myeloma
Hypothyroidism (e.g. hashimotos)
Aplastic anaemia
Haemolysis (shift to immature red cell form - reticulocytosis)
Drugs (e.g. tyrosine kinase inhibitor)
Pregnancy
summarise the epidemiology of macrocytic anaemia?
More common in ELDERLY FEMALES
Pernicious anaemia is the MOST COMMON cause of B12 deficiency in the West
what are the presenting symptoms of macrocytic anaemia?
Non-specific symptoms of anaemia:
- Tiredness
- Lethargy
- Dyspnoea
Family history of autoimmune disease
Previous GI surgery
Symptoms of the CAUSE (e.g. weight loss, diarrhoea)
what are the categories for the signs of macrocytic anaemia?
sign of anaemia
signs of pernicious anaemia
signs of B12 deficiency
folate deficiency symptoms
what are the 3 main signs of anaemia?
pallor
tachycardia
breathlessness
what are the signs of pernicious anaemia?
mild jaundice
glossitis
angular stomatitis
weight loss
what are the signs of b12 deficiency on physical examination?
Peripheral neuropathy
Ataxia
Subacute combined degeneration of the spinal cord
Optic atrophy
Dementia
Positive Babinski’s, absent ankle reflex, increase knee reflex
Neuro symp
- numbness
- Paraethesia
- reduced sense of taste
- muscle weakness
- depression
what are the symptoms of folate deficiency?
symptoms related to anaemia
Diarrhoea
Headache
Loss of appetite and weight loss
what are the investigations for macrocytic anaemia?
bloods
blood film
schilling test
Bone marrow biopsy ( rarely needed)
Describe bloods in B12 deficiency?
FBC
- High MCV
- Pancytopaenia in megaloblastic anaemia
- Different degrees of cytopaenia in myelodysplasia
- Exclude reticulocytosis
LFT
- High bilirubin (due to ineffective erythropoiesis or haemolysis)
ESR
TFT
Serum vitamin B12
Red cell folate
Anti-parietal cell (90%) and anti-intrinsic factor antibodies (40-60%)
Serum protein electrophoresis - looking for a dense band in myeloma
Describe the blood film in macrocytic anaemia?
Large erythrocytes
In megaloblastic anaemia:
- Megaloblasts
- Hypersegmented neutrophil nuclei
- Target cells if liver disease
what is the schilling test?
Method for testing for pernicious anaemia
B12 only absorbed when given with IF
Generate a management plan for macrocytic anaemia
Pernicious Anaemia
- IM hydroxycobalamin (version of vitB12) for life
- If no neurological defect-> IM hydroxycobalamin 1mg 3x/week for 2 weeks then 1mg/3 months
- If neurological defect present-> 1mg every other day until no further improvement then 1mg/2 months
B12 deficiency – life-long therapy
- Rarely but may need a blood transfusion
- Dietary supplements – PO cyanocobalamin or IM 1000mg of hydroxocobalamin every 3 months
Folate Deficiency
- Oral folic acid
- If B12 deficiency is present, it must be treated before the folic acid deficiency as B12 is needed for folate to enter cells
- In pregnancy, prophylactic folate is given from conception until 12 weeks to prevent spina bifida
what are the complications of macrocytic anaemia?
Pernicious anaemia –> increased risk of gastric cancer
Pregnancy - folate deficiency increases the risk of neural tube defects
Summarise the prognosis for patients with macrocytic anaemia
Majority are treatable if there are no complications
