Thrombotic thrombocytopenic purpura in a patient with HIV from Zimbabwe

Abstract

A woman in her 40s originally from Zimbabwe presented to our accident department in the UK with a 4 day history of menorrhagia and exertional chest pain. Her clinical examination was unremarkable. Routine blood tests revealed a haemoglobin value of 6.8 g/dl and a platelet count of 15×10(9)/l, with normal renal function and coagulation profile. Blood film showed microangiopathic haemolytic anaemia and thrombocytopenia. On direct questioning, she admitted to being HIV positive, and receiving antiviral therapy at another hospital. A diagnosis of HIV associated thrombotic thrombocytopenic purpura (TTP) was made. The patient was transferred to a tertiary centre for urgent plasma exchange. She required 8 days of 1.5 litre exchanges with solvent detergent fresh frozen plasma (FFP) and high dose steroids. She responded within 24 h with increasing haemoglobin and platelet counts, and at discharge her haemoglobin was 10.7 g/dl and platelet count 253×10(9)/l.

Antiplatelet Therapy in Acute Coronary Syndrome

“…It is administered orally and up to 85 % of the absorbed drug undergoes hepatic metabolism by carboxylesterases to form an inactive carboxylic acid derivative, clopidogrelic acid, whilst the remaining 15 % is metabolised into the active thiol product by cytochrome P450 isoenzymes. 23,26 Although clopidogrel has a relatively short half-life of 6 hours, 27 28 Variable responses to clopidogrel may additionally result from mutations in the ABCB1 gene that encodes the P-glycoprotein involved in clopidogrel absorption. 28 The standard dosing regime is a 300 mg loading dose and 75 mg daily maintenance dose.…”

“…Following this, steady state ADP inhibition is typically achieved within 3-7 days, with a 40-60 % reduction in ADPinduced platelet aggregation from baseline. 27 Randomised controlled trials have demonstrated that clopidogrel is more effective than aspirin in preventing cardiovascular events in patients with vascular disease, 29 reduces mortality further in patients with MI when used alongside aspirin, 30 and improves outcomes in patients undergoing PCI again when used in combination with aspirin. 31,32 The Clopidogrel versus Aspirin in Patients at Risk of Ischaemic Events (CAPRIE) study showed that clopidogrel administration was associated with similar adverse effects to those observed with aspirin, including gastrointestinal discomfort and increased bleeding, but the overall safety profile of clopidogrel 75 mg daily was considered to be at least as good as that of aspirin 325 mg daily.…”