CASE 8: DIC, ITP, TTP Flashcards
1
Q
DIC lab results
A
- Prothrombin time (PT) - prolonged
- Activated partial thromboplastin time (APTT) - prolonged
- Fibrinogen (derived and Clauss) - lowered. Derived fibrinogen is calculated based on APTT so if APTT is prolonged will be inaccurate so do Clauss instead
- Platelets - lowered
- Fibrin degradation products are often raised
- Schistocytes due to microangiopathic haemolytic anaemia
- D-dimer: high
2
Q
DIC diagnosing
A
- Presenting features: sick patient, bleeding from venepuncture site, lots of bruising, rarely new VTE, Micro-vascular thrombosis causing organ dysfunction
- Scoring system like ISTH (>5 indicates DIC)
3
Q
Treating DIC
A
- Treat the condition causing the thrombosis
- IV Vitamin K replacement to support the production of clotting factors
- Maintain physiological pH and calcium levels
- Maintain body temperature
- Heparin limited to management of thrombosis in chronic DIC
- Give Heparin
4
Q
DIC what to do in severe bleed
A
- Consider replacement
- 1 pool of platelets (if they are <75 x 109/L)
- 2 pools of cryoprecipitate (if fibrinogen <1.5g/dL)
- 4 units of fresh frozen plasma to replace coagulation factors and natural anticoagulants
5
Q
Acute and chronic DIC
A
- Acute DIC occurs when large amounts of tissue factor are released over a short duration, not allowing for compensatory increase in platelets/ factors- Profound bleeding, which can be mucocutaneous or deep, including oozing from lines, catheters and surgical sites
- Chronic DIC occurs when small amounts of tissue factor are released over time, allowing compensatory increase in platelet and factor production, but also resulting in build up of procoagulants (i.e. in malignancy)- Can be asymptomatic or have microvascular, arterial or venous thrombi, leading to end-organ damage
6
Q
DIC investigations
A
- FBC, blood film, LDH, bilirubin, haptoglobin, reticulocyte count, INR, APTT, fibrinogen, liver enzymes, creatinine
- β-HCG, septic work up as appropriate for clinical situation
7
Q
DIC clinical examination
A
- Signs of haemorrhage: bleeding from cannula sites/venepuncture sites, melaena, haematemesis, rectal bleeding, epistaxis, haemoptysis, haematuria
- Petechiae or purpura
- Livedo reticularis:a mottled lace-like patterning of the skin
- Purpura fulminans:widespread skin necrosis
- Localised infarction and gangrene for instance of the digits
- Confusion
- Oliguria, hypotension and/or tachycardia:signs of circulatory collapse, which is associated with DIC
8
Q
ITP- idiopathic thrombocytopenic purpura
A
- Must have low platelet count <100 BUT many causes for this
- Increased immune destruction of platelets and/or reduced production of platelets
- Platelets destroyed by antiplatelet antibodies which are removed in the liver and spleen
- Antibodies can also target Megakarocytes (precursor to platelets) in the bone marrow causing reduced production
- Diagnosis of exclusion when you cant identify another cause of thrombocytopenia
- Response to ITP specific therapy support diagnosis. If doesn’t respond to multiple therapies re-consider diagnosis
9
Q
Primary and secondary ITP
A
- Primary ITP: isolated thrombocytopenia with no co-existing condition. Viral infection can proceed ITP
- Secondary ITP is associated with co-existing condition: Rheumatological disease, CLL, lymphoma, viral infection, various pharmacological agents
10
Q
Length of ITP
A
- Newly diagnosed when thrombocytopenia is present for less than 3 months;
- Persistent ITP refers to thrombocytopenia of 3 to 12 months;
- Chronic ITP is defined as thrombocytopenia >12 months.
11
Q
Differential causes of thrombocytopenia
A
- High risk conditions: [HIV, HCV, HBV]), SLE
- Liver disease: cirrhosis or portal hypertension
- Splenomegaly
- Drugs: heparin, valproate, alcohol abuse, consumption of quinine (tonic water), exposure to environmental toxins, or chemotherapy
- Bone marrow diseases: leukemias, other malignancies, metastatic disease, myelofibrosis, aplastic anemia, megaloblastic anemia
- Other thrombocytopenic disorders (DIC, TTP, HUS, Evans syndrome)
12
Q
Investigations in ITP causes
A
- Blood film: reduced platelets
- FBC, U&E, LFT, clotting factors, reticulocyte count, LDH, INR, APTT
- Hepatitis and HIV serology
- Bone marrow biopsy: should be normal
- Ultrasound abdomen
- Vitamin B12 and folate (rare for deficiency to cause isolated thrombocytopenia), viral screen (e.g. HCV, HIV), ANA, quantitative immunoglobulins , HIT assay, APS testing, testing for PNH, VWD screen, platelet function testing
13
Q
Labs in ITP
A
- Platelets <100 x 109/l, usually 10-50 109/l. Hb and WBC normal
- Large platelets on blood film. Normal PT/APPT
- Increased megakaryocytes on bone marrow biopsy
14
Q
Who gets ITP
A
- Children: common post viral illness or vaccination. Abrupt onset, usually no treatment needed. Recover in weeks-months. Don’t do any contact sports- reduce trauma or injury
- Adults: often insidious onset, consider in pregnancy if platelets <80. Treatment is needed if platelets <20. 20% are secondary. Chronic course. Spontaneous remissions are rare. Can present in pregnancy (consider if platelet count <80)
15
Q
Bleeding symptoms in ITP
A
- Mucosal Bleeding: nose bleeds, gum bleeding, oral blood blisters, menorrhagia, bruises and petechiae (more common in legs), purpuric lesions (where petechiae coalesce)
- 1/3 are asymptomatic
- Fatigue
- Paradoxical thrombotic events: stroke and TIA
- Trauma-related bleeding
- Intracranial bleeding- warn about head injury
- Most common cause of death: haemorrhage and infection
16
Q
Treatment in ITP
A
- First Line treatment: Corticosteroids, IVIG, tranexamic acid (mucosal bleeding symptoms)
- Platelet infusions- in life threatening haemorrhage but will have shorter survival with auto-antibody cross reaction
- Second line thrombopoietin receptor agonists (TPO-RA) i.e. avatrombopag, immunosuppressive agents, e.g. MMF (Mycophenolate Mofetil), azathioprine, rituximab
- Splenectomy- can cause long term remission, has complications of infection or thrombosis risk so rarely undertaken
17
Q
Recommended target platelet counts for surgery and invasive procedures
A
- In patients with chronic ITP you do not normally need treatment unless haemorrhaging. Can receive treatment before surgery to reach ideal platelet count
- > 30 for simple dental extraction
- > 50 for complex dental extraction/ minor surgery
- > 80 for major surgery
- > 100 for neurosurgery
18
Q
Prognosis for ITP
A
- Chronic disorder which is relapsing and remitting
- Most patients have good outcomes
- In steroid refractory ITP and chronic ITP, splenectomy should be considered.
19
Q
Pseudo thrombocytopaenia, diffusion thrombocytopaenia
A
Pseudo thrombocytopenia: Giant platelets. Platelet clumping due to EDTA-dependent agglutinins – repeat using citrated tube
Dilutional thrombocytopenia: Post massive transfusion / fluids. Gestational thrombocytopenia
20
Q
Thrombocytopenia decreased production
A
- Congenital – e.g. TAR (thrombocytopenia with absent radius), amegakaryocytic thrombocytopenia, VWD (type 2B)
- Drugs (alcohol, chemotherapy)
- Radiation
- Aplastic anaemia
- Bone marrow replacement (e.g. malignancy, granuloma, fibrosis)
- Infection/sepsis
- B12 or folate deficiency
- Ineffective haematopoiesis – myelodysplasia
