anaemia Flashcards
what is anaemia?
anaemia is a reduction in haemoglobin in the blood
What are reasons for haemoglobin issues?
inability to make haem (iron deficiency) to inability to make correct globing chains (sickle cell anaemia/thalassemia)
What are the causes of anaemia?
- reduced production of haemoglobin
- increased losses of haemoglobin
- increased demand for haemoglobin (due to increase in tissue or increase tissue metabolism rate)
What may indicate the cause of anaemia?
size of RBCs (MCV)
Give 2 examples of haemoglobinopathies.
thalassemia and sickle cell disease
what does autosomal recessive mean? Give an example of an autosomal recessive disease.
- the disease only occurs if maternal and paternal pass on the defect gene
- sickle cell anaemia
what mutation causes sickle cell anaemia?
point change mutation in beta globing chain
Complications of sickle cell anaemia?
RBCs change shape in reduced oxygen levels preventing them from passing through capillaries. This blocks circulation causing pain, ischaemia and necrosis.
The abnormal haemoglobin chains function normally at standard oxygen levels.
Describe the difference between heterozygous and homozygous in sickle cell anaemia.
Heterozygous means they carry one abnormal allele and do not display symptoms (sickle cell trait)
Homozygous means they carry 2 abnormal alleles, have sickle cell disease and display symptoms.
What are haematinics?
Used to make RBCs, Folic acid, iron and vitamin B12
Give examples of production failure causing anaemia.
Bone marrow failure -> reduced RBC -> not enough RBC to package haemoglobin into
Reduced haemoglobin due to deficiencies in elements needed to make haemoglobin - iron, folic acid, vit B12
Describe non-haem iron?
- iron 2+ or 3+ valency
- can only be absorbed by conversion from 3+ to 2+ first then through specific haem transporter system
- non-haem iron is harder for body to deal with than haem iron
How is iron stored in a cell?
stored as ferritin then passed into blood for circulation and reprocessing
How are RBCs reprocessed?
reprocessed through macrophages and then into bone marrow through the haem reprocessing system to allow new RBCs and haem to be made.
what is achlorhydria?
- disease reducing iron absorption
- lack of stomach acid
- no conversion of non-haem iron
how does coeliac disease reduce iron absorption?
affects intestinal villi and therefore the body’s ability to absorb iron
How can iron loss occur?
- bleeding into GI tract
- bleeding elsewhere in body
- gastric erosions and ulcers
- inflammatory bowel disease (ulcerative colitis and Crohn’s)
- haemorrhoids
- bowel cancer
how is vit b12 absorbed?
- secretion of intrinsic factor by gastric parietal cells
- vit b12 from diet binds to intrinsic factor
- passes to terminal ileum where it is absorbed by specific transporting system
How does vit B12 deficiency occur?
- comes from meat and dairy so lack of intake
- vegans have issue
- lack of intrinsic factor in stomach
- disease of terminal ilium e.g. Crohn’s
- monthly injections to treat
where is folic acid absorbed?
- small bowel (same as iron)
- diseases affecting iron absorption also affect FA absorption
What cause folic acid deficiency?
- lack of intake
- absorption failure e.g. coeliac
- FA deficiency in a pregnant mother can lead to neural tube defects in foetus (spinal bafida)
How are haematinic deficiencies measured?
blood test
Alpha thalassemia, beta thalassemia and sickle cell disease are examples of what?
haemoglobin abnormalities.
Give different reasons anaemia presents
-reduced RBCs due to marrow failure normal RBCs but reduced Haemoglobin -deficiency in Fe, FA or vitB12 -abnormal globing chains (thalassemia, sickle cell anaemia) -chronic inflammatory disease
where is haemoglobin manufactured in early life?
liver and spleen
where is haemoglobin manufactured after birth?
bone marrow
when is alpha haemoglobin made?
throughout life
when is beta haemoglobin made and why?
mainly after birth because baby can breathe on its own and beta is then preferred to gamma haemoglobin
Explain function of gamma haemoglobin?
remove oxygen from the maternal circulation to filter into foetal circulation for babies oxygen needs. gamma haemoglobin is reduced after birth as baby can breathe on their own.
what is thalassemia?
- genetic mutation of globing chains making normal formation of alpha or beta globing chains difficult
- normal haem production
what are the clinical effects of thalassemia?
- chronic anaemia
- marrow hyperplasia as marrow gets bigger to produce more haemoglobin (skeletal deformities)
- splenomegaly - spleen used to recycle RBCs, the RBCs are abnormal and don’t live long therefore the turnover is greater
- cirrhosis due to excess iron in body
- gall stones due to haem reprocessing
what is splenomegaly?
abnormal enlargement of the spleen
what is the management of thalassemia?
blood transfusions, already have enough haem so need to then prevent iron overload as this will cause cirrhosis
what is microcytic anaemia?
small RBC caused by Fe deficiency or thalassemia
what is macrocytic anaemia?
large RBC due to b12/folate deficiency or reticulocytes (developing RBC)
RBCs shrink as they form so common reason for microcytic is that RBCs are immature and not shrunk enough
what is normocytic anaemia?
normal RBC size but reduced total haemoglobin
- due to bleed, chronic disease or renal disease
what does hypochromic mean in anaemia?
RBCs appear pale under microscope due to less haemoglobin in cells
- can be micro, macro or normo but most commonly microcytic
what does anisocytic mean in anaemia?
RBCs are an exaggerated range of sizes from very large to very small in same sample
How might Fe deficiency present to a dentist?
- candidiasis
-mucosal atrophy/thinning
recurrent oral ulceration
-sensory change
what are the 3 measurements for diagnosing anaemia?
- haemoglobin
- what is the red cell count (RCC) and hematocrit (HCT)
- what is the mean cell volume (MCV)
What does the RCC tell us?
if anaemia is associated with normal or reduced RBC
what does the hematocrit tell us?
whether there are fewer cells in the blood
what will MCV show?
raised MCV or reduced MCV will indicate macrocytosis or microcytosis and indicate the likely deficiency
What are the common causes of blood loss?
GI bleeding
menstrual blood loss
What happens to an abnormal RBC?
they will have a reduced lifespan and be removed by the spleen (can be due to autoimmune or hereditary disease)
what is the treatment of anaemia?
treat the cause
- address GI bleeding
- replace haematinics through supplements or diet
- erythropoietin injection if renal disease is the issue
- blood transfusion where there is production failure, only RBCs and haemoglobin need transfused
what are the signs and symptoms of anaemia?
signs- pale, tachycardia, enlarged liver and spleen, pale mucosa
symptoms-tired, weak, dizzy, SOB, palpitations
loss of tongue papillae and angular chelitis may indicate …
iron deficiency
beefy/swollen tongue may indicate…
vit B12 deficiency
what are the investigations for anaemia?
- history
- full blood count
- haematinics
- GI blood loss via FOB test, endoscopy, colonoscopy or black stools
- RBCs are triggered by erythropoietin so check renal function
- bone marrow examination if still unexplained
What are reticulocytes?
almost mature RBCs that are usually held in bone marrow until all organelles are removed but can be released prematurely in times of need to replace losses. They are larger than RBCs so will raise MCV
when may reticulocytosis be seen?
when a patient has lost blood and is rapidly trying to replace O2 carrying capacity e.g. by trauma or blood donation
