MACROCYTIC ANAEMIA Flashcards
(23 cards)
What is a simple explanation of macrocyclic anaemia?
Type of anaemia which occurs due to a your red blood cells becoming too big and so they can’t function properly. Because of this there are fewer blood cells so they can’t carry as much oxygen around your body.
What is the epidemiology?
Fairly common. Peak age diagnosis is 60. More common in females. Often a FH.
How is macrocytosis caused?
Macrocytosis is caused by a problem in the synthesis of red blood cells as opposed to microcytosis which is due deficiency of haemoglobin production. Megaloblast = a cell in which nuclear maturation is delayed compared with the cytoplasm.
What is Megaloblastic caused by?
B12 deficiency, folate deficiency, cytotoxic drugs
What is Non-megaloblastic caused by?
Alcohol, reticulocytosis (eg in haemolysis), liver disease, hypothyroidism, pregnancy
• Alcohol abuse, Liver disease, Reticulocytosis, Severe hypothyroidism, Pregnancy, Myelodysplasia, Myeloma, Myeloproliferative disorders, Aplastic anaemia
What haemolytical disease caused by?
myelodysplasia, myeloma, myeloproliferative disorder, aplastic anaemia
Vit B12 deficiency is caused by?
- Autoimmune pernicious anaemia
- After surgery such as gastrectomy or ileal reseaction
- Bacterial overgrowth or parastic infestation
- HIV infection
- Dietary deficiency – esp in vegans
- Pernicious anaemia - esp in elderly
- Congenital abnormalities in metabolism
Folate deficiency is caused by?
- Dietary def
- Malabsorption
- Increased demands including haemolysis, leukaemia
- Incr urinary excretion due to HF, acute hep and dialysis
- Drug-induced def incl alcohol, anticonvulsants, methotrexate
Risk factors
- Family History, increasing age, female
- Low dietary intake; Impaired absorption (pernicious anaemia, celiac disease); Abnormal utilisation (congential transcobalamin ll deficiency).
- Symptoms?
- SOB on exertion
- Fatigue
- Palpitations
- Exacerbation of angina
- Complaining of looking pale
- Irritability
- Paraesthesia (pins and needles)
Signs
- Pallor
- Lemon tinge to skin due to pallor from anaemia and mild jaundice (due to haemolysis)
- Glottitis (beefy red sore tongue)
- Angular cheilosis
- Systolic pul flow murmur
- Bounding pulse
- Depression/psychosis/dementia
- Paraesthesiae, peripheral neuropathy
SUBACUTE COMBINED DEGENERATION OF THE SPINAL CORD
Onset is insidious (sub acute) with peripheral neuropathy due to decr B12. Combined symmetrical dorsal column loss causing sensory and LMN signs and symmetrical corticospinal tract loss causing motor and UMN signs. Can lead to ataxia and joint stiffness and weakness if untreated. Classic triad: Extensor plantars; Absent knee jerks; Absent ankle jerks. NB. Pain and temp remains due to STT preserved.
What investigations should you do?
BLOODS BONE MARROW SERUM BILIRUBIN SERUM METHYLMALONIC ACID (MMA) AND HOMOCYSTEINE (HC) SERUM VIT B12 SERUM FOLATE
How would you investigate for pernicious anaemia?
- Parietal cell antibodies
* Intrinsic factor antibodies (target B12 binding sites or ileal binding sites)
What will the investigation show?
- Low Hb
- High MCV – macrocytic
- Hypersegmented nuclei
- Reticulocytes – indicate rapid turnover or erythrocytes
What do the bloods show?
- Aneamia; MCV >96fL
- Peripheral blood film: macrocytes with hypersegmented polymorphs w/ 6 or more lobes in the nucleus
- If severe, then leucopenia or thrombocytopenia
What will you see in the bone marrow?
large cells, large immature nuclei, chromatin is finely dispersed, giant metamyelocytes are frequently screen (twice size of normal cells and twisted nuclei)
What change in bilirubin?
May be raised as a result of ineffective erythropoeisis and premature breakdown of RBC. LDH can also be incr due to haemolysis
What change in homocysteine?
Raised in B12 def. HC rasied in folate def only
Change in serum Vit B12?
usually <160ng/L (lower end of normal range)
Change in Serum Folate?
normally normal or high
How do you treat folic deficiency?
folci acid 5mg/d PO for 4/12. Never without B12 unless pt known to have normal B12 (may ppt or worsen sub acute degeneration of cord in pt with low B12)
How do you treat B12 deficiency?
If cause malabsoption: IM hydroxycobalamin 1000mcg to a total of 5-6mg over 3 weeks, then 1mg IM every 3/12 for life. If cause is orally: 2mg/d. Clinical improvement in 48hr.
What is pernicious anaemia?
Caused by AI atrophic gastritis, leading to anchlorhydria and lack of gastric intrinsic factor secretion.
Incidence 1:1000
More common F
Usually >40
Higher incidence blood group A
Ass w/ o/ AI conditions, thyroid disease, Addisons, hypoparathyroidism, Ca of stomach
