Intricacies Of Treating Heparin Induced Thrombocytopenia With Preexisting Antiphospholipid Syndrome and Renal Insufficiency

Treatment of heparin induced thrombocytopenia (HIT) requires the use of alternatives anticoagulants, such as a direct thrombin inhibitor – argatroban. Use of argatroban relies on frequent laboratory monitoring of the activated partial thromboplastin time (aPTT) to maintain an adequate level of anticoagulation. This requirement poses a challenge in patients with prolonged baseline aPTT, such as in antiphospholipid syndrome. While other assays are being explored they require an extended turn around time because of their limited availability.

We present a case of a 63 year old male with a history of antiphospholipid syndrome, end stage renal disease on hemodialysis, hepatitis C, and on long term anticoagulation with warfarin for cerebral vein thrombosis. His hospital course required transition to unfractionated heparin and subsequently developed thrombocytopenia. A heparin-platelet factor 4 ELISA antibody assay was performed for an intermediate clinical likelihood of HIT and returned positive. Although not confirmed with the gold standard serotonin release assay (SRA), clinical suspicion for HIT obligated treatment with an alternative anticoagulant. Conventional dosing and administration of argatroban however could not be performed because of the patient’s prolonged baseline aPTT. Other agents such as fondaparinux were also not possible in the setting of renal insufficiency. Short of other treatment techniques accepted in this unique set of circumstances we practiced a fixed dose argatroban (0.5 mcg/kg/min for Child’s class B cirrhosis). The patient tolerated the empiric dosing well until discontinued because of a negative SRA. This case demonstrates the limitations of current treatment recommendations of HIT and need for further investigation in similar patients.