Blood: Anaemias

Question 1

What is sickle-cell disease caused by?

Answer 1

Structural abnormality of haemoglobin resulting in deformed, less flexible red blood cells. Acute complications in the more severe forms include sickle-cell crisis, where infarction of the microvasculature and blood supply to organs results in severe pain.

Question 2

What drug can reduce the frequency of crises and the need for blood transfusions in sickle-cell disease? When do the beneficial effects of treatment with this drug become evident? (both generic drug and brand name begin with ‘H’)

Answer 2

Hydrea, Hydroxycarbamide, beneficial effects may not become evident for several months.

Question 3

What is G6PD deficieny? Who is it more prevalent in?

Answer 3

Glucose 6-phosphate dehydrogenase deficiency is highly prevalent in people from Africa, most parts of Asia, Oceania and Southern Europe. More common in males than females.

Question 4

Individuals with G6PD are susceptible to developing what?

Answer 4

Acute haemolytic anaemia when they take are number of common drugs or when they eat fava beans (broad beans): Favism, can be severe in children or when eaten raw.

Question 5

What three points should be kept in mind when prescribing for patients with G6PD deficieny?

Answer 5

1. It is genetically heterogenous: haemolytic risk varies and just because a drug is safe in one individual with the disease does not mean it is safe in another.
2. Manufacturers do not routinely test drugs for their effects in G6PD-deficient people.
3. The risk and severity of haemolysis is almost always dose-related.

Question 6

What antibiotics have a definite risk of haemolysis in most G6PD-deficient people?

Answer 6

1. Nitrofurantoin
2. Quinolones
3. Sulfonamides (including co-trimoxazole)

Question 7

What drug used in the prophylaxis and treatment of acute hyperuricaemia, before and during initiation of chemotherapy, in patients with haematological malignancy and high tumour burden at risk of rapid lysis has a definite risk of haemolysis in patients with G6PD-deficiency?

Answer 7

Rasburicase

Question 8

What are Epoetins?

Answer 8

Recombinant human erythropoietins.

Question 9

What are Epoetins (Recombinant human erythytopoietins) used for? (3)

Answer 9

1. To treat anaemia associated with erythropoietin deficiency in chronic renal failure.
2. To increase the yield of autologous blood in normal individuals.
3. To shorten the period of symptomatic anaemia in patients receiving cytotoxic chemotherapy.

Question 10

What is Epoetin beta used for the prevention of in preterm neonates of low birth-weight and why should only unpreserved formulatins be used?

Answer 10

Prevention of anaemia and only unpreserved formulations should be used because other preparations may contain benzyl alcohol.

Question 11

What are the benefits of darbepoetin alfa versus epoetin?

Answer 11

It is a hyperglycosylated derivative which has a longer half life and can be administered less frequently.

Question 12

Methoxy polyethylene glucol-epoetin beta is a continous erythropoietin receptor activator that is licensed for what?

Answer 12

Treatment of symptomatic anaemia associated with chronic kidney disease - longer duration of action than epoetin.

Question 13

Treatment with an iron preparation is justified only in the presence of demonstrable iron-deficiency state. Before starting treatment, what should be excluded?

Answer 13

Gastric erosion

Gastro-intestinal cancer

Question 14

The oral dose of elemental iron for iron-deficiency anaemia should be what?

Answer 14

100-200mg elemental iron daily.

Question 15

Some oral preparations of iron contain ascorbic acid for what reason

Answer 15

To aid absorption but the therapeutic advantage of such preparations is minimal and cost may be increased

Question 16

Patenteral iron is generally reserved for use when oral therapy is unsuccessful but it may have a role in the management of what?

Answer 16

Chemotherapy-induced anaemia, when given with erythropoietins.

Question 17

Ascorbic acid is licensed for the treatment and prophylaxis of what?

Answer 17

Scurvy

Question 18

Most megaloblastic anaemias result from a lack of what?

Answer 18

Either vitamin B12 or folate, it is essential to establish in every case which deficiency is present and the underlying cause.

Question 19

One cause of megaloblastic anaemia in the UK is what?

Answer 19

Pernicous anaemia

Question 20

What is pernicous anaemia?

Answer 20

A lack of gastric intrinsic factor resulting from an autoimmune gastritis causes malabsorption of vitamin b12.

Question 21

Vitamin b12 is needed in the treatment of megaloblastosis cause by prolonged what?

Answer 21

Prolonged nitrous oxide anaesthesia as it inactivates the vitamin.

Also in the rare syndrome of congenital transcobalamin II deficiency.

Question 22

Vitamin B12 should be given prophylactically after what?

Answer 22

total gastrectomy or total ileal resection.

Question 23

Hydroxocobalamin has completely replaced cyanocobalamin as the form of vitamin b12 of choice. Why?

Answer 23

It is retained in the body longer and thus maintenance therapy can be given of intervals of up to 3 months.

Question 24

Why should folic acid not be used in undiagnosed megaloblastic anaemia unless vitamin B12 is administered concurrently?

Answer 24

Neuropathy may be precipitated.

Question 25

In folate-deficient megaloblastic anaemia (e.g. because of poor nutrition, pregnancy, or AEDs) daily folic supplementation for how long brings about haematological remission and replenishes body stores?

Answer 25

4 months of treatment.

Question 26

For prophylaxis in chronic haemolytic states, malabsorption, or renal diaylsis, folic acid is given how often?

Answer 26

Daily or weekly, depending on the diet and the rate of haemolysis.

Question 27

Folinic acid is also effective in the treatment of folate deficient megaloblastic anaemia but it is generally used in associated with what?

Answer 27

Cytotoxic drugs, it is given as calcium folinate.