Saturday, September 23, 2023

Concept Map: AKI in ECMO


Concept Map of pathophysiology related to AKI in a patient on ECMO- created by Dr. Purva Sharma using 

Consult Rounds: BK in non renal solid organ transplantation

What is the incidence of BK viremia, and BK Nephropathy in non renal solid organ transplants?

Not much that I could find in the literature.

In this retrospective study from 2021, the authors investigated the clinical characteristics, pathological findings, and outcomes of BK viremia and nephropathy in non-renal solid organ transplant patients (NRSOT) who sought nephrology consultation over a five-year period. Among liver, heart, and lung transplant recipients referred to Nephrology, 14% were diagnosed with BK viremia, with a median peak serum BK viral load of 35,500 copies/ml (ranging from 250 to 21,100,000 copies/ml). Notably, BK viremia resolved in six out of seventeen patients (35%), but four out of five biopsied patients exhibited BK virus (BKV) nephropathy. Furthermore, eleven out of the seventeen patients with BK viremia progressed to advanced stages (stage 4 or 5) of chronic kidney disease. Additionally, four patients experienced rejection of their solid organ transplant within the first year following the detection of BK viremia after reducing immunosuppressive treatments. This may be a sign of just net immunosuppression.

Another study back in 2019 had looked at literature systematically on report of BK disease in native kidneys. In their review at that time, in heart transplant recipients, 13 cases of BKV nephropathy had been reported, with most occurring in males (10 out of 13), and the mean age being 36.6 years. In lung transplant patients, six cases of BKV nephropathy were identified, with a mean diagnosis age of 47.3 years. Only one case of BKV nephropathy was reported in a liver transplant recipient, and one in a pancreas transplant recipient. More have been reported since their report. The average time from transplant to BKV nephropathy diagnosis in the solid organ transplant population was 2.88 years. For patients who had undergone hematopoietic cell transplantation (HSCT), 19 cases of BKV nephropathy were found, with a mean diagnosis age of 30.6 years. In cases with demographic information, 58% were males, and half of these patients required renal replacement therapy, with a mortality rate of 63.2%. Ten cases of BKV nephropathy were reported in the context of hematologic malignancies, with an average time from malignancy diagnosis to BKV nephropathy diagnosis of 3.06 years. Ten cases of BKV nephropathy were reported in HIV-infected patients, all in males, with a mean age of 34.5 years. Three of these patients required renal replacement therapy, and mortality at the time of publication was 30%. Additionally, individual cases of BKV nephropathy were described in various other clinical settings, such as rheumatoid arthritis, Hyper IgM immunodeficiency syndrome, pulmonary tuberculosis, diabetes mellitus, prostate cancer, and an immunocompromised patient with an unclear medical history. This is fascinating to note that this entity has been ignored in the recent non renal transplant literature. 

In a meta-analysis evaluating the frequency and risk factors for BK viruria and viremia in NRSOT patients, Viswesh et al found a relatively high rate of viruria (8%-52%) but infrequent progression to viremia (3%-7%) and BKV nephropathy (1 biopsy-proven case in an heart transplant recipient). Among those NRSOT patients who did have progression to viremia and BKV nephropathy, heart transplants patients represented the majority of cases. This finding might be due to the proposed “double-hit” hypothesis, which suggests that the cumulative insult of immunosuppression and renal hypoperfusion secondary to cardiac allograft dysfunction causes clinical progression to BKV nephropathy.  

Should implementing a systematic BK screening program could effectively identify and manage this issue in the NRSOT population and or HCT patients?

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