Korean J Transplant.  2022 Nov;36(Supple 1):S285. 10.4285/ATW2022.F-4255.

Intrapatient variability of tacrolimus in a recurrently ill kidney transplant recipient

• Yeom J
• Lee S

• KMID: 2535512
• DOI: http://doi.org/10.4285/ATW2022.F-4255

Abstract

Tacrolimus is a key immunosuppressant used in kidney transplant patients. A 73-year-old female patient presented with a fe-ver and sputum who had received deceased kidney transplantation for end-stage renal disease due to diabetic nephropathy 15 years ago. She had a baseline serum creatinine ranging from 0.7 to 0.9 mg/dL, and maintenance of immunosuppression has been stable with triple therapy. She was released from quarantine due to a COVID-19 infection the day before ER visit. A chest computed tomography scan showed multifocal ground glass opacities on both lungs compatible with COVID-19 pneumonia. Nevertheless, the blood test showed that the level of the inflammatory marker was not high (high-sensitivity C-reactive protein [hsCRP], 5.72 mg/L). Therefore, she was discharged with oral antibiotics and discontinuation of mycophenolate mofetil (MMF). A week later, the patient's condition deteriorated, and she was admitted to the hospital again. According to blood test results on admission, the patient's white blood cell count was 10,410 cells/L; creatinine, 0.94 mg/dL; hsCRP, 152 mg/L. A chest X-ray revealed pneumonia aggravation. Furthermore, the urine culture was reported 2 days later, Pseudomonas aeruginosa grew, and the stool toxin assay confirmed the presence of Clostridioides difficile. The last tacrolimus level measured before hospitalization was 8.54 ng/mL, but on the 5th day of admission, it rose sharply to 20.14 ng/mL despite no interacting drug. Thus, we reduced the tacrolimus dose, stopped MMF, and administered antibiotics for pneumonia and C. difficile infection (CDI). Finally, she was discharged with full recovery 10 days after. However, the patient presented with fever and bloody loose stool three months after the last hospitalization. A stool exam revealed the recurrence of CDI, serum hsCRP (68 mg/L), and tacrolimus levels (16 ng/mL) repeatedly increased with stable kidney function. We experienced the tacrolimus level increase whenever the infection requir-ing hospitalization occurred, and the increase was more significant in the presence of overlapping infection in the kidney trans-plant recipient.