see also: [[Thrombotic Thrombocytopaenic purpura]], [[ITP]], [[Haemolytic uraemic syndrome|HUS]], [[microangiopathic haemolytic anaemia]], [[Pre-eclampsia#HELLP]], [[Petechiae]] #tables #cram > - plt <50 risk of bleeding following injury > - <10 risk of spontaneous haemorrhage > **plt cut of for procedures** (need transfusion first) > - LP: <50 > - central line: <20 > - asymptomatic patient: <10 | | [[Thrombotic Thrombocytopaenic purpura\|TTP]] | [[DIC]] | [[ITP]] | [[Haemolytic uraemic syndrome\|HUS]] | | --------------------------------------- | ----------------------------------------------------------------------------------------------------------------------------------------------------------- | ---------------------------------------------------------------------------------------------------- | --------------------------------------------------------------------------------------------------- | -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | | plt count | ↓ | ↓ | ↓ | ↓ | | INR/PT | normal | ↑ | normal | normal | | [[microangiopathic haemolytic anaemia]] | present | [? present](https://thrombosisjournal.biomedcentral.com/articles/10.1186/s12959-018-0168-2) | absent | present | | fibrinogen | normal | ↓ | normal | normal | | safe to give platelets? | no | yes-ish | yes | no | | history/exam | - plavix / late pregnancy / OCP<br>- Fever, headache, seizures, nausea/ vomiting/ abdo pain<br>- renal impairment <br>- tx: FFP, plasma exchange, steroids) | - rapid onset of severe illness<br>- febrile<br>- signs of shock<br>- ecchymosis with poor perfusion | - recent viral illness<br>- otherwise well child<br>- normal vitals<br>- isolated thrombocytopaenia | - recent GI illness (Shiga e coli) +/- bloody<br>- oligo/anuria or haematuria<br>- abdo pain common<br>- elevated LDH, reduced haptoglobin<br>- haemolysis (schistocyts on film) | ==note== that *HSP* has **normal** platelet count and normal coags Heparin-induced thrombocytopenia not on table **most common causes of isolated thrombocytopaenia**: - *pregnancy* - responsible for 75% of thrombocytopenia in pregnancy - plt count drops progressively with increases gestational age - returns to normal within 2 months of delivery - usually no issue for mum or fetus if not associated with any other disease - [[ITP]] - drug induced thrombocytopaenia - chemo - pseudothrombocytopenia - plt clumping on sample in EDTA tube - doesn't happen with sodium citrate (clotting studies) tube - only moderate reduction decreased production: - haematological malignancies - aplastic anaemia - radiation/chemotherapy - B12 def - chronic [[Alcohol-related disease|EtOH abuse]] - thiazides - infections - [[measles]] - [[HIV]] - faonconi anaemia - paroxysmal nocturnal haemoglobinuria - wiskott-aldrich syndrome - x linked inheretance - dermatitis - impaired cellulra and humeral immunity increased destruction or consuption - immune - [[ITP]] - [[DIC]] - [[Sepsis]] - [[Dengue]] - [[Malaria]] - COVID-19 - [[Rickettsia]] - [[leptospirosis]] - [[Ebola]] - drugs (hundreds possible) - **heparin-induced thrombocytopaenia** (HITS) - phenytoin - quinidine - sulphonamides - vancomycin - NSAIDs - paracetamol - aspirin - lasix - amiodarone - valproate - [[Thrombotic Thrombocytopaenic purpura|TTP]] - [[Haemolytic uraemic syndrome|HUS]] - vasculitis - rheumatoid arthritis - SLE and antiphospholipid syndomre - haematological malignancies - CLL - lymphoma - hepatitis C - immunodeficiency - HIF - IgA def - hypogammaglobulinaemia Hpersplenism -- eg due to [[Sickle Cell Anaemia]] Trauma proesthetic heart valves post transfusion purpura - rare complication, uusally 1 week following transfusion - usually in multparous women sensitised to human platelet-specific antigens through pregnancy # Exam - prominant petachiae - usually lowr limbs - areas of cutaneous pressure - splenomegaly - # specific conditions ## heparin-induced thrombocytopaenia (HITS) - increased BMI and age >40 is risk factor - usually after 1 week of therapy ; can be within 24 hours in previously sensitised individuals type 1: self resolving type 2: IgG mediated, worse outcome **management** argatropan or hirudin