Kidney transplant recipients (KTRs) are at increased risk of severe
COVID-19 disease compared to the general population. This is partly driven by their use of immunosuppressive therapy, which influences inflammatory responses and viral loads. Current guidelines suggest to withdraw mycophenolate while
calcineurin inhibitors are often continued during a
COVID-19 infection. However, clinical signs of
calcineurin toxicity have been described in multiple
COVID-19 positive KTRs. In this report we describe the course of
tacrolimus exposure prior to, during, and post
COVID-19 in observations from three clinical cases as well as four KTRs from a controlled trial population. We postulate
inflammation driven downregulation of the
CYP3A metabolism as a potential mechanism for higher
tacrolimus exposure. To mitigate the risk of
tacrolimus overexposure and toxicity therapeutic drug monitoring is recommended in KTRs with
COVID-19 both in the in-, out-patient and home monitoring setting.