Haematology Conditions Flashcards
(9 cards)
What is the definition and epidemiology of Haemochromatosis?
Haemochromatosis is a multisystem disorder resulting from excessive intestinal iron absorption which may lead to organ damage (particularly liver, joints, pancreas, pituitary and heart).
The most common form occurs mainly in people of northern European descent. Carrier frequency is ~1 in 10, but not all express disease. Prevalence of those affected 1 in 400. Typical age of presentation is 40-60 years.
- Females have a later onset and a less severe presentation as a result of iron loss through menstruation.
What is the aetiology of Haemochromatosis?
Primary haemochromatosis is caused by a mutation in HFE gene, decreased levels of hepcidin, and thus increased duodenal iron absorption.
Secondary haemochromatosis is a result from blood transfusions, as after the erythrocytes are broken down, the iron is recycled.
What are the clinical features of Haemochromatosis?
May be asymptomatic. Non-specific symptoms such as weakness, fatigue and lethargy are common. Other symptoms are due to common complications:
- Liver: symptoms of cirrhosis e.g. jaundice, ascites, hepatomegaly.
- Pancreas: malabsorption problems and type I diabetes
- Skin: bronze pigment
- Heart: cardiomyopathy, arrhythmias
- Gonads: signs of hypogonadism and libido
- Joints: small/large joint pains.
What are the investigations for Haemochromatosis?
- ↑Iron, ↓TIBC (Total Iron Binding Capacity measures ferritin), ↑ferritin and transferrin saturation.
- HFE mutation analysis is usually only done when there is a family history of the disease.
- Test various organs for complications e.g. liver biopsy, LFTs, fasting blood sugar, echocardiogram, ECG, testosterone, FSH and LH assays.
Describe the management of Haemochromatosis
Lifestyle modification mainly revolves around dietary changes:
- Diet low in iron
- Restriction of alcohol and vitamin C supplements
- Consumption of tea (as tannins bind to iron and prevent absorption)
Therapeutic venesection is the first-line treatment. Monitoring adequacy of venesection: transferrin saturation should be kept below 50% and the serum ferritin concentration below 50 ug/l.
Drug-induced iron chelation may be done on occasions when venesection is contraindicated.
What are the clinical features of coagulation factor disorders?
What are the different types of haemophilia?
Haemophilia results from the inherited deficiency of clotting products. There are three subtypes:
- Haemophilia A: (most common) caused by deficiency in factor VIII.
- Haemophilia B: Caused by deficiency in factor IX (Christmas disease).
- Haemophilia C: (rare) caused by deficiency in factor XI.
Haemophilia A and B exhibit X-linked recessive inheritance. A variety of genetic mutations in the factor VIII and XI genes have been described. 30% of cases are new mutations. X-linked pattern means it affects males (1-5/10,000 for Haemophilia A and 1/30,000 for Haemophilia B). Rare cases of women
with severe haemophilia are described because of extreme lyonization, homozygosity, mosaicism, or Turner syndrome.
What are the investigative features of haemophilia?
Clotting screen:
- ↑APTT (reflects the activity of the intrinsic and common pathway), coagulation factor assay shows ↓Factor VIII or IX or XI (depending on type of haemophilia).
- Normal bleeding time as primary haemostasis still occurs.
- Also normal thrombin time and prothrombin time normal
Other investigations according to complications e.g. arthroscopy, head/neck CT/MRI, pelvic US.
What is the management of haemophilia?
- Substitution of clotting factors is usually when needed (e.g., trauma or surgery) for mild-moderate haemophilia, or prophylactic for severe haemophilia.
- Desmopressin may be indicated in some cases of haemophilia A (as vasopressin causes release of factor VIII from endothelial cells)
