Blood Disorders Flashcards
Why do we need iron?
- Haemoglobin synthesis
- Catecholamine synthesis
- Heat production
- Component of certain enzymes needed for production of adenosine triphosphate involved in cell respiration
- We have approximately 2.3g total body iron of which most (80%) is found in the red blood cells (functional iron =Hb)
- Iron not in use stored as soluble protein ferritin, present primarily in liver, bone marrow, spleen and skeletal muscle (myoglobin,20%)
- Body can absorb 1-2mg daily from diet, with aid of absorption enhancers in diet and satisfactory rate of RBC production
- Main factor controlling iron absorption is amount of iron stored in the body and the type of iron in the diet
- Iron from meat, poultry, and fish (i.e., haem iron) is absorbed two to three times more efficiently than iron from plants (i.e., non-haem iron).
- Foods containing haem iron (meat, poultry, and fish) enhance iron absorption from foods that contain non- haem iron (e.g., fortified cereals, some beans, and spinach).
- Foods containing vitamin C also enhance non-haem iron absorption when eaten at the same meal.
- Foods or drinks such as tea (tannins), bran (phytates), and milk or dairy products (calcium)can decrease the amount of non-haem iron absorbed at a meal.
- Vegetarian diets are low in haem iron, but careful meal planning can help increase the amount of iron absorbed.
- Drugs which can reduce iron absorption = antacids, histamine antagonists (cimetidine, ranitidine), methyldopa, calcium supplements
Measurement of functional iron
- Hb (late indicator)
- Haematocrit ( proportion of rbc, only falls after Hb so again a late sign)
- Mean Cell Volume (MCV) also falls in iron deficiency but differential diagnosis needed as can fall in other conditions i.e. thalassaemia
- Serum Ferritin Concentration – measurement of stored iron (15-200μg/l normal) ≤30 μg/l =iron deficiency ≤12 μg/l = iron deficiency anaemia
Why do iron requirements increase?
- Growth
- Menstruation
- Blood/loss/donation
- Pregnancy
- Haemolytic disorders
- Drugs that cause haemolysis (e.g antiretrovirals)
- Genitourinary tract infections
- Hookworm infestations
Complications
- Palpitations/ tachycardia
- Tiredness
- Irritability
- Depression
- Breathlessness
- Poor memory
- Muscle aches
- Poor appetite
- Cardiac failure
Treatments
- Increased vulnerability to blood loss
- Encourage iron rich food
- Complementary iron supplements – spa-tone, floradix
- FeS04 60-120mg/day for 4/52 (1hr after food with orange or apple juice)
- store carefully as little as 2g can be fatal for a child (antidote desferrioxamine)
- Parental iron (iron dextran or iron sucrose)
o Rise in reticulocyte counts and Hb of 0.8 g/dl/wk occurs 5-10 days after starting both
o Usually used if oral not tolerated
o More rapid response
o Sometimes used as an alternative to blood transfusion
o CONTRAINDICATED IN THE FIRST TRIMESTER
Iron requirements in a singleton in pregnancy
- 200-600mg to meet increase in red cell mass
- 200-370mg for the fetus, depending on birth weight
- 140-200mg as external loss
- 30-170mg for the cord and placenta
- 90-130mg to cover blood loss at delivery = total demands range between 580-1,340mg
Megaloblastic anaemia
- Megaloblasts = immature red blood cells
- Characterised by macrocytosis = mean Cell volume > normal range 80-95 femtolitres (fl) and they have immature nuclei
- results from inhibition of DNA synthesis in red blood cell production.
- When DNA synthesis is impaired, the cell cycle cannot progress from the growth stage to the mitosis stage.
- This leads to continuing cell growth without division, which presents as macrocytosis.
- Megaloblastic anemia has a rather slow onset, the symptoms develop rather slowly , especially when compared to that of other anemias
Causes
- Caused by a deficiency of folic acid or Vit B12 which are absorbed in gut
- More rarely may be drug induced
- Non –megloblastic = liver disease, hypothyroidism and alcoholism
Dietary folate and B12 and its absorption
- Vegetables, beans, rice, liver and meat
- Degraded by prolonged boiling
- Daily requirement roughly 3mcg per Kg (rises in pregnancy 400mcg a day)
- Absorption mainly through the jejunum
- Folate-free diet causes deficiency in a few weeks
Dietary B12 and its absorption
- “everything that walks, swims or flies contains B12. Nothing that grows out of the ground contains B12”
- Intrinsic factor-development absorption from terminal ileum
- Requirements 1-3mcg a day
- Vitamin B12 free diet causes deficiency after years
Causes of folate deficiency
- Inadequate intake
- Malabsorption i.e. coeliac disease
- Excess utilisation – pregnancy, haemolysis, cancer
- Drugs i.e. anticonvulsants, sulfasalazine, methotrexate
Causes of B12 deficiency
- Inadequate intake
- Absorption defects – blind loop syndrome, tropical sprue
- Intrinsic factor deficiency – pernicious anaemia, gastrectomy or ileal resection
Pernicious anaemia
- Part of the family of megaloblastic anaemias
- It is caused by loss of gastric parietal cells, which are responsible, in part, for the secretion of intrinsic factor, a protein essential for subsequent absorption of vitamin B12 in the ileum.
- Intrinsic factor is a protein, which is made in the stomach, attaches to vitamin B12 and carries through the intestinal wall into the blood stream
Complications - Pallor and jaundice
- Increasingly severe anaemia
- Heart failure
- Pancytopaenia (low wbc + platelets)
- Fetal neural tube defects
- Smooth painful tongue (glossitis)
Aplastic anaemia
- Aplastic anaemia is a condition where bone marrow does not produce sufficient new cells to replenish blood cells
- involves both aplasia and anaemia
- Typically, anaemia refers to low red blood cell counts, but aplastic anaemia patients have lower counts of all three blood cell types: rbc, wbc, and platelets, termed panycytopenia
Effect of anaemia on pregnancy
Pregnancy issues
- Cervical dysplasia- cervical cancer
- Loss of appetite and maternal weight loss
- Glossitis
- Increased risk neural tube defects
- Increased risk of fetal cleft palate
- IUGR
- Maternal exhaustion in labour
- Post partum haemorrhage
- If BF human milk has a folate content of 5mcg/dl therefore levels are further depleted = supplementation several weeks PN
Antenatal Care
- Initial risk assessment and screening
- Documentation of testing
- Follow-up and acting on results
-Interventions/treatment/management
o Informed consent/choice for client
o Monitoring concordance with treatment offered or suggested
- Communication of findings
o With client
o With colleagues and others in multidisciplinary team
- Frequency of testing (FBC, ferritin, folate)
- Labour/birth planning
o Consider special needs if client unable to accept blood products
Intrapartum Care
- Most recent FBC result available
- How well equipped is the client to tolerate or withstand blood loss, either normal or ‘haemorrhage’, associated with childbirth?
- What interventions or procedures may increase the risk of haemorrhage occurring? Could they be avoided?
e.g. use of oxytocin; 3rd stage management; perineal trauma
- What could be done to minimise risks?
o IV access (“in case”)
o IV fluids (volume replacement)
o Blood transfusion (last resort); other blood products
Postnatal care
- Demands of postnatal recovery and infant care
o Self care; daily living activities; family relationships
o Infant care; adjusting to new role as a parent
- Capacity for effective infant feeding
- Need for wound healing
o Perineal trauma
o Caesarean section
o ‘Surgical’ removal of retained tissue
Throbocytopenia in pregnancy
- Reduced platelet (thrombocyte) count
- Leads to bleeding in the skin = purpura and can result in spontaneous bruising and post- injury bleeding
- 50% of cases in pregnancy will be directly related to pre-eclampsia
- Gestational thrombocytopenia 5-8% of pregnancies
- Immune thrombocytopenic Purpura 0.1% of pregnancies
Gestational thrombocytopenia and Immune thrombocytopenic purpura
Gestational thrombocytopenia
- Also known as incidental thrombocytopenia
- Exclusive to pregnancy
- Presents late 2nd or third trimester
- Exact pathophysiology unknown? Haemadilution,? Increased platelet activation
- Usually benign and asymptomatic
- Usually falls to around 50-150 X 109/l
- Returns to normal usually by 6/52 PN
Immune thrombocytopenic purpura
- Used to be called idiopathic thrombocytopenic purpura
- Can present acutely after a viral infection (often in children)
- Alternatively can be chronic affecting young to middle aged women
- May present for the first time in pregnancy
- Results from the body producing IgG autoantibodies that act against its own platelets
- Reduces lifespan from 10days to a few hours
- Bone marrow cannot keep pace with replacement so can drop to 10-140 x 109/l
- Most cases idiopathic but can be secondary to drugs, HIV and connective tissue disorders
- Diagnosis difficult need to exclude SLE and von- Willebrand’s and 30% do not have antibodies detected on laboratory investigations
Complications
- Impaired haemostasis
- Bleeding from nose and gums
- Bruising
- Menorrhagia and secondary anaemia
- Splenomegaly (rare)
- Major haemorrhage (rare)
- Side effect of steroidal Rx = diabetes, hypertension
Bleeding disorders
Inherited Bleeding Disorders
- Haemophilia A (Classical haemophilia)
o Deficiency or absence of factor VIII
o X-linked chromosomal disorder
o Affects around 1:5000-10,000 males
- Haemophilia B (Christmas disease)
o Deficiency in factor IX
o X-linked chromosomal disorder
- Von Willebrand’s disease
o The most common bleeding disorder
o Deficiency or abnormal function of vWF
