Post-transplant monitoring and ancillary evaluation
General laboratory evaluation. Typical post-transplant monitoring labs are shown in Table 2. KDIGO suggests (with low evidence of support) that labs be obtained two to three times per week for weeks 2-4 and then weekly for months 2 and 3, every two weeks for months 4-6, monthly for months 7-12, and then every two to three months thereafter.
Our team obtains a complete blood count (CBC), renal panel—which includes phosphorus, calcium, and albumin levels, in contrast to a basic metabolic panel (BMP)—and CNI and/or mammalian target of rapamycin (mTOR) inhibitor levels weekly for the first 16 weeks and then every other week up to one year, and then monthly. This is less frequently than suggested by KDIGO early after transplantation and more frequently later. This reflects our appreciation for the decreased incidence of early events and a need for monitoring long term when we are not able to see patients in the clinic.
At our center, a complete metabolic panel is substituted for the renal panel to assess liver function tests quarterly. We also assess uric acid quarterly because asymptomatic hyperuricemia is associated with CNI use and may be associated with cardiovascular complications, necessitating the use of allopurinol. We obtain a serum magnesium level quarterly because the CNIs and mTORs cause magnesium wasting. We obtain a fasting lipid panel and creatine kinase because most of our patients are dyslipidemic and on a statin (See below).
Proteinuria. For patients with FSGS, we obtain a random urine protein-to- creatinine ratio prior to discharge after transplantation, four times weekly and then quarterly. We obtain a dipstick urinalysis at each clinic visit. For those with new onset proteinuria we obtain a random urine protein-to-creatinine ratio and follow these at least quarterly. It is important to realize that most native residual kidney function, and thus native kidney proteinuria, ceases by about four to six weeks.5 Thus, proteinuria after six weeks is probably coming from the transplanted kidney.
Cytomegalovirus. Monitoring for cytomegalovirus (CMV) is unnecessary during the period of prophylaxis with valganciclovir. However, some patients cannot afford valganciclovir and a preemptive approach is used. For these patients, weekly CMV-PCRs for the first 12 weeks is recommended. This is because CMV most commonly reactivates in the first three months after transplantation and a diligent preemptive approach has been shown to be as cost-effective as prophylaxis in preventing symptomatic disease.19 However, CMV prophylaxis is easier and in some studies, prophylaxis has been associated with less acute rejection and better long-term outcomes than preemptive therapy.20, 21
Epstein-Barr virus. We do not usually monitor EBV since interpretation is complicated and the sensitivity and specificity are poor for either post-transplant lymphoproliferative disease (PTLD) or EBV-associated disease. We are required to obtain special approval from our laboratory medicine colleagues to order an EBV-PCR in the hospital. However, among patients suspected of having PTLD, or among EBV-seronegative patients such as diabetics or children, prospective EBV monitoring may allow earlier recognition of a predisposition to PTLD that may be prevented with immunosuppressive reduction.22
BK virus. We monitor BK-PCRs in the blood monthly for the first six months, at months 9 and 12, and then for cause. This is a modification of the consensus guidelines and reflects studies that show that BK viruria is uncommon in the absence of BK viremia, which seldom occurs before month 1 post-transplant. The incidence rapidly increases by three months and plateaus by six months. Sustained viremia may be a precursor to BK-virus nephropathy.23