Hydroxychloroquine-Associated Thrombotic Thrombocytopenic Purpura

Thrombotic microangiopathy (aHUS/iTTP) reported so far in Covid-19 patients: The virus alone or an omnium gatherum of mechanisms and etiologies?

“…All these cases responded to plasma exchange while in Capecchi’s study besides plasma exchange anti-vWF nanobody caplacizumab was given as well. In Arikan’s case RT-PCR was negative for SARS CoV 2 infection and IgG-antibody testing for Covid-19 was not done but a strong probability score favoring HCQ induced iTTP was established with the authors concluding that the iTTP being secondary to HCQ however, contrasted to this particular patient HCQ/quinine induced TTP is not a typical iTTP and has not been associated with a critical drop in ADAM-TS 13 levels or the presence of an antibody against the same which on the one hand calls into question the diagnosis made by these authors and on the other even attributes iTTP to HCQ as a novel complication ( Albiol et al, 2020 ; Hindilerden et al, 2020 ; Arikan et al, 2020 ; Capecchi et al, 2020 ; Mir, 2021 ; Altowyan et al, 2021 ).…”

Hydroxychloroquine, TTP, COVID-19, and SLE

“…The recent report entitled “Hydroxychloroquine-associated thrombotic thrombocytopenic purpura” (TTP) was very interesting [ 1 ]. Arıkan et al [ 1 ] concluded that the patient represented a possible case of hydroxychloroquine-induced TTP and called for awareness of this possible adverse effect of hydroxychloroquine (HQ) in alternative therapy for coronavirus disease-19 (COVID-19). In fact, TTP might be the result of many disorders.…”

Immune Thrombotic Thrombocytopenic Purpura in a Patient with Suspected COVID-19: Hydroxychloroquine Culprit or Just Happenstance?

“…I read with great interest the recently published letter to the editor by Arıkan et al [ 1 ] about hydroxychloroquine (HCQ)-associated thrombotic thrombocytopenic purpura (TTP) together with some queries raised by Sookaromdee and Wiwanitkit and the original authors’ reply [ 1 , 2 ]. There are some pertinent points to note.…”

“…However, typical drug-induced TTP, including quinine-induced TTP, is not associated with a critical drop in ADAMTS13 levels or with the presence of an ADAMTS13 inhibitor, but the patient presented by Arıkan et al had both. This is an important differentiating feature of quinine-induced TTP from immune TTP (iTTP) and it calls into question the diagnosis made by Arıkan et al [ 1 ] or even suggests iTTP after HCQ as a novel complication [ 3 ]. I would not straight away repudiate the observation made by Arıkan et al [ 1 ] because, first of all, there is a definite temporal profile that links the medicine with iTTP, and, furthermore, some drugs like the thienopyridine group of antiplatelets have been associated with classic iTTP leading to a critical drop in ADAMTS13 levels and the presence of an inhibitor [ 4 ].…”

“…This is an important differentiating feature of quinine-induced TTP from immune TTP (iTTP) and it calls into question the diagnosis made by Arıkan et al [ 1 ] or even suggests iTTP after HCQ as a novel complication [ 3 ]. I would not straight away repudiate the observation made by Arıkan et al [ 1 ] because, first of all, there is a definite temporal profile that links the medicine with iTTP, and, furthermore, some drugs like the thienopyridine group of antiplatelets have been associated with classic iTTP leading to a critical drop in ADAMTS13 levels and the presence of an inhibitor [ 4 ]. At least five cases of thrombotic microangiopathy of iTTP/HUS (hemolytic uremic syndrome) in coronavirus disease-19 (COVID-19) have been reported in the literature with an obvious temporal relation between HCQ and the development of iTTP, which seems to have been ignored by most authors in light of COVID-19 infection and everything being attributed to this novel virus [ 5 , 6 , 7 , 8 ].…”