Platelet-Independent defect in hemostasis associated with sirolimus use

Area of Science:

• Nephrology
• Hematology
• Pharmacology

Background:

• Sirolimus (rapamycin) is an immunosuppressant crucial for preventing solid organ transplant rejection.
• Sirolimus-eluting stents are utilized to prevent coronary artery restenosis.
• Thrombocytopenia is a recognized adverse effect of sirolimus, often limiting its clinical application.

Observation:

• A 52-year-old female renal transplant recipient developed fever, anorexia, and asthenia four months post-transplantation.
• Despite a normal platelet count and function, the patient exhibited prolonged bleeding times (over 30 minutes) and impaired fibrin formation.
• Elevated serum sirolimus levels (25.9 ng/mL) correlated with worsening renal function and bleeding complications.

Findings:

• Sirolimus induced a platelet-independent hemostasis defect characterized by impaired fibrin formation and reduced fibrinolysis.
• The patient's bleeding disorder resolved upon sirolimus discontinuation, with concurrent improvement in renal function and normalization of bleeding times.
• This case demonstrates a novel mechanism of sirolimus-induced bleeding beyond its known association with thrombocytopenia.

Implications:

• Clinicians should consider sirolimus-induced hemostasis defects in transplant patients presenting with unexplained bleeding, even with normal platelet counts.
• Monitoring coagulation parameters and serum drug levels is essential for managing patients on sirolimus therapy.
• Further research is warranted to elucidate the precise mechanisms underlying sirolimus-related hemostatic abnormalities.