Severe labile hypertension in a patient with catecholamine-secreting neuroblastoma: a case report.

Neuroblastoma is a common pediatric tumor arising from the post-ganglionic sympathetic nervous system and is associated with hypertension in 25% of cases. We describe an unusual case of labile, multi-drug resistant hypertension associated with chemotherapy administration for neuroblastoma and provide potential management strategies in this scenario. We report the case of a 4-year-old female with a history of headaches who presented with hypertensive emergency and evidence of end-organ damage, including posterior reversible encephalopathy syndrome, acute cerebral infarct, concentric left ventricular hypertrophy, and growth failure secondary to a large, abdominal catecholamine-secreting neuroblastoma, which compressed the kidney vasculature and inferior vena cava. She was classified as intermediate risk according to Children's Oncology Group criteria and underwent chemotherapy, complicated by labile hypertension, followed by surgical resection. Vigilance in monitoring and treatment of hypertension is recommended during chemotherapy for neuroblastoma due to the potential catecholamine release in the setting of tumor lysis.

The Preserving Kidney Function in Children With CKD (PRESERVE) Study: Rationale, Design, and Methods.

Rationale & Objective: PRESERVE seeks to provide new knowledge to inform shared decision-making regarding blood pressure (BP) management for pediatric chronic kidney disease (CKD). PRESERVE will compare the effectiveness of alternative strategies for monitoring and treating hypertension on preserving kidney function; expand the National Patient-Centered Clinical Research Network (PCORnet) common data model by adding pediatric- and kidney-specific variables and linking electronic health record data to other kidney disease databases; and assess the lived experiences of patients related to BP management. Study Design: Multicenter retrospective cohort study (clinical outcomes) and cross-sectional study (patient-reported outcomes [PROs]). Setting & Participants: PRESERVE will include approximately 20,000 children between January 2009-December 2022 with mild-moderate CKD from 15 health care institutions that participate in 6 PCORnet Clinical Research Networks (PEDSnet, STAR, GPC, PaTH, CAPRiCORN, and OneFlorida+). The inclusion criteria were ≥1 nephrologist visit and ≥2 estimated glomerular filtration rate (eGFR) values in the range of 30 to <90 mL/min/1.73 m2 separated by ≥90 days without an intervening value ≥90 mL/min/1.73 m2 and no prior dialysis or kidney transplant. Exposures: BP measurements (clinic-based and 24-hour ambulatory BP); urine protein; and antihypertensive treatment by therapeutic class. Outcomes: The primary outcome is a composite event of a 50% reduction in eGFR, eGFR of <15 mL/min/1.73 m2, long-term dialysis or kidney transplant. Secondary outcomes include change in eGFR, adverse events, and PROs. Analytical Approach: Longitudinal models for dichotomous (proportional hazards or accelerated failure time) and continuous (generalized linear mixed models) clinical outcomes; multivariable linear regression for PROs. We will evaluate heterogeneity of treatment effect by CKD etiology and degree of proteinuria and will examine variation in hypertension management and outcomes based on socio-demographics. Limitations: Causal inference limited by observational analyses. Conclusions: PRESERVE will leverage the PCORnet infrastructure to conduct large-scale observational studies that address BP management knowledge gaps for pediatric CKD, focusing on outcomes that are meaningful to patients. Plain-Language Summary: Hypertension is a major modifiable contributor to loss of kidney function in chronic kidney disease (CKD). The purpose of PRESERVE is to provide evidence to inform shared decision-making regarding blood pressure management for children with CKD. PRESERVE is a consortium of 16 health care institutions in PCORnet, the National Patient-Centered Clinical Research Network, and includes electronic health record data for >19,000 children with CKD. PRESERVE will (1) expand the PCORnet infrastructure for research in pediatric CKD by adding kidney-specific variables and linking electronic health record data to other kidney disease databases; (2) compare the effectiveness of alternative strategies for monitoring and treating hypertension on preserving kidney function; and (3) assess the lived experiences of patients and caregivers related to blood pressure management.

Acute kidney injury requiring kidney replacement therapy in childhood lupus nephritis: a cohort study of the Pediatric Nephrology Research Consortium and Childhood Arthritis and Rheumatology Research Alliance.

BACKGROUND: Acute kidney injury (AKI) is common in lupus nephritis (LN) and a risk factor for development of chronic kidney disease. In adults with LN, AKI severity correlates with the incidence of kidney failure and patient survival. Data on AKI outcomes in children with LN, particularly those requiring kidney replacement therapy (KRT), are limited. METHODS: A multicenter, retrospective cohort study was performed in children diagnosed between 2010 and 2019 with LN and AKI stage 3 treated with dialysis (AKI stage 3D). Descriptive statistics were used to characterize demographics, clinical data, and kidney biopsy findings; treatment data for LN were not included. Logistic regression was used to examine the association of these variables with kidney failure. RESULTS: Fifty-nine patients (mean age 14.3 years, 84.7% female) were identified. The most common KRT indications were fluid overload (86.4%) and elevated blood urea nitrogen/creatinine (74.6%). Mean follow-up duration was 3.9 ± 2.9 years. AKI recovery without progression to kidney failure occurred in 37.3% of patients. AKI recovery with later progression to kidney failure occurred in 25.4% of patients, and there was no kidney recovery from AKI in 35.6% of patients. Older age, severe (> 50%) tubular atrophy and interstitial fibrosis, and National Institutes of Health (NIH) chronicity index score > 4 on kidney biopsy were associated with kidney failure. CONCLUSIONS: Children with LN and AKI stage 3D have a high long-term risk of kidney failure. Severe tubular atrophy and interstitial fibrosis at the time of AKI, but not AKI duration, are predictive of kidney disease progression. A higher resolution version of the Graphical abstract is available as Supplementary information.

Design and Methods of the Validating Injury to the Renal Transplant Using Urinary Signatures (VIRTUUS) Study in Children.

Lack of noninvasive diagnostic and prognostic biomarkers to reliably detect early allograft injury poses a major hindrance to long-term allograft survival in pediatric kidney transplant recipients. METHODS: Validating Injury to the Renal Transplant Using Urinary Signatures Children's Study, a North American multicenter prospective cohort study of pediatric kidney transplant recipients, aims to validate urinary cell mRNA and metabolite profiles that were diagnostic and prognostic of acute cellular rejection (ACR) and BK virus nephropathy (BKVN) in adult kidney transplant recipients in Clinical Trials in Organ Transplantation-4. Specifically, we are investigating: (1) whether a urinary cell mRNA 3-gene signature (18S-normalized CD3ε, CXCL10 mRNA, and 18S ribosomal RNA) discriminates biopsies with versus without ACR, (2) whether a combined metabolite profile with the 3-gene signature increases sensitivity and specificity of diagnosis and prognostication of ACR, and (3) whether BKV-VP1 mRNA levels in urinary cells are diagnostic of BKVN and prognostic for allograft failure. RESULTS: To date, 204 subjects are enrolled, with 1405 urine samples, including 144 biopsy-associated samples. Among 424 urine samples processed for mRNA, the median A260:280 ratio (RNA purity) was 1.91, comparable with Clinical Trials in Organ Transplantation-4 (median 1.82). The quality control failure rate was 10%. Preliminary results from urine supernatant showed that our metabolomics platform successfully captured a broad array of metabolites. Clustering of pool samples and overlay of samples from various batches demonstrated platform robustness. No study site effect was noted. CONCLUSIONS: Multicenter efforts to ascertain urinary biomarkers in pediatric kidney transplant recipients are feasible with high-quality control. Further study will inform whether these signatures are discriminatory and predictive for rejection and infection.

Practice patterns and influence of allograft nephrectomy in pediatric kidney re-transplantation: A pediatric nephrology research consortium study.

INTRODUCTION: There are no guidelines regarding management of failed pediatric renal transplants. MATERIALS & METHODS: We performed a first of its kind multicenter study assessing prevalence of transplant nephrectomy, patient characteristics, and outcomes in pediatric renal transplant recipients with graft failure from January 1, 2006, to December 31, 2016. RESULTS: Fourteen centers contributed data on 186 pediatric recipients with failed transplants. The 76 recipients that underwent transplant nephrectomy were not significantly different from the 110 without nephrectomy in donor or recipient demographics. Fifty-three percent of graft nephrectomies were within a year of transplant. Graft tenderness prompted transplant nephrectomy in 91% (P < .001). Patients that underwent nephrectomy were more likely to have a prior diagnosis of rejection within 3 months (43% vs 29%; P = .04). Nephrectomy of allografts did not affect time to re-listing, donor source at re-transplant but significantly decreased time to (P = .009) and incidence (P = .0002) of complete cessation of immunosuppression post-graft failure. Following transplant nephrectomy, recipients were significantly more likely to have rejection after re-transplant (18% vs 7%; P = .03) and multiple rejections in first year after re-transplant (7% vs 1%; P = .03). CONCLUSIONS: Practices pertaining to failed renal allografts are inconsistent-40% of failed pediatric renal allografts underwent nephrectomy. Graft tenderness frequently prompted transplant nephrectomy. There is no apparent benefit to graft nephrectomy related to sensitization; but timing / frequency of immunosuppression withdrawal is significantly different with slightly increased risk for rejection following re-transplant.

Human Papillomavirus Vaccination in Male and Female Adolescents Before and After Kidney Transplantation: A Pediatric Nephrology Research Consortium Study.

Background: Kidney transplant (KT) recipients have higher incidence of malignancies, including Human Papillomavirus (HPV)-associated cancers. Thus, HPV vaccines may have an important role in preventing HPV-related disease in this population; however, immunogenicity and safety data are lacking. Objective: To examine the immunological response and tolerability to HPV vaccination in pediatric KT recipients compared to future KT candidates. Methods: The quadrivalent HPV vaccine was administered to girls and boys age 9-18 recruited from seven centers part of the Pediatric Nephrology Research Consortium. Subjects were recruited for three groups: (1) CKD: chronic kidney disease stages 3, 4, and 5 not on dialysis; (2) Dialysis; (3) KT recipients. The outcome consisted of antibody concentrations against HPV 6, 11, 16, and 18. Geometric mean titers (GMTs) and seroconversion rates were compared. Vaccine tolerability was assessed. Results: Sixty-five participants were recruited: 18 in the CKD, 18 in the dialysis, and 29 into the KT groups. KT patients had significantly lower GMTs after vaccination for all serotypes. The percentages of subjects who reached seroconversion were overall lower for the KT group, reaching statistical significance for HPV 6, 11, and 18. Comparing immunosuppressed subjects (anyone taking immunosuppression medications, whether KT recipient or not) with the non-immunosuppressed participants, the former had significantly lower GMTs for all the HPV serotypes and lower seroconversion rates for HPV 6, 11, and 18. KT females had higher GMTs and seroconversion rates for certain serotypes. There were no adverse events in either group. Conclusions: HPV vaccine was well-tolerated in this population. Pediatric KT recipients had in general lower GMTs and seroconversion rates compared to their peers with CKD or on dialysis. Immunosuppression played a role in the lack of seroconversion. Our results emphasize the importance of advocating for HPV vaccination prior to KT and acknowledge its safety post transplantation. Future studies are needed to investigate the effect of a supplemental dose of HPV vaccine in KT recipients who do not seroconvert and to evaluate the long-term persistence of antibodies post-KT.

Use of oral immunoglobulins to treat diarrhea in pediatric kidney transplant recipients-Single-center experience and review of the literature.

Effective treatment modalities for diarrhea in solid organ transplant recipients are lacking. We evaluated the effect of oral IgG on clinical course of diarrhea in pediatric kidney transplant recipients. We retrospectively studied all pediatric kidney transplant recipients who required hospitalization for diarrhea between January 1, 2015, and December 31, 2017. We divided the recipients into two groups based on whether they had received oral IgG to treat diarrhea. Sixteen pediatric kidney transplant recipients required hospitalization for diarrhea over 3 years. Median age at admission was 9.25 years (IQR:12.54). Fifty-six percent of recipients were male, and 81% were white. Four patients received oral IgG for prolonged diarrhea. Oral IgG recipients had longer diarrheal duration before admission (median (days) 14.5 vs1; P .02), a trend for greater weight loss at admission (median (kilogram) 1.4 vs 0.2; P .3), and a trend for higher acute kidney injury (>75% reduction in glomerular filtration rate: 100% vs 42%; P .36). Diarrhea resolved completely in 3 (75%) oral IgG recipients and 7 (58%) non-oral IgG patients by discharge (P .99). One oral IgG recipient showed partial improvement but also had biopsy evidence of mycophenolate-induced colitis. All patients tolerated oral IgG well. No patients required re-hospitalization within 30 days of discharge. Oral IgG may be used safely and effectively to treat prolonged diarrhea in pediatric kidney transplant recipients. A larger, randomized, prospective study is needed to further assess the efficacy of oral IgG in the treatment of diarrhea.

Pediatric Nephrology and Rheumatology Practice Patterns in Granulomatosis with Polyangiitis: A Midwest Pediatric Nephrology Consortium Study.

OBJECTIVE: To assess practice pattern similarities and differences amongst pediatric rheumatologists and nephrologists in the management of pediatric Granulomatosis with Polyangiitis (GPA). METHODS: A voluntary survey was distributed to the Midwest Pediatric Nephrology Consortium Group (MWPNC) and an international pediatric rheumatology email listserv in 2016-2017. Data were collected on general practice characteristics and preferences for induction management under three clinical scenarios (A-C): newly diagnosed GPA with glomerulonephritis, GPA with rapidly progressive glomerulonephritis, and GPA with pulmonary hemorrhage. In addition, individual preferences for GPA maintenance medications, disease monitoring, and management of GPA with end-stage renal disease were ascertained. RESULTS: There was a 68% response rate from the MWPNC membership and equal numbers of rheumatology respondents. Survey results revealed Rituximab plus Cyclophosphamide is a more common induction choice for rheumatologists than nephrologists in induction Scenarios A and B, whereas Cyclophosphamide is more commonly chosen by nephrologists in Scenario A. Plasmapheresis rates increased for Scenarios A, B, and C for both specialties, but were overall low. There was no clear consensus on the duration of maintenance therapy nor diagnostic work-up. Rheumatologists more frequently chose Rituximab for maintenance and induction compared to nephrologists. There was also a higher than expected proportion of Mycophenolate Mofetil use for both specialties. CONCLUSION: This survey has revealed important differences in the way that rheumatologists and nephrologists manage this disease. It highlights the need for well-designed clinical trials in pediatric GPA patients and reveals that both specialties must be represented during consensus-building and clinical trial design efforts.

Primary Epstein-Barr virus infection.

Epstein-Barr virus (EBV) infects about 90% of adults worldwide. It is the main cause of infectious mononucleosis, which is observed most frequently in adolescents. The disease can last several weeks and is characterized by lymphocytosis, sore throat, lymphadenopathy, and fatigue. Exposure to oral secretions during deep kissing has been identified as the major source for primary EBV infection in adolescents. Oral secretions are also thought to be the source for younger children through intimate intact or sharing food and eating utensils, although this has not been confirmed. Unlike most acute viral illnesses such as influenza, the incubation period of symptomatic primary EBV infection is unusually long, lasting about six weeks. Diagnosis is typically made by heterophile antibody tests and/or EBV-specific antibody tests. Long-term consequences may result from acquisition of the virus, including nasopharyngeal carcinoma and lymphomas. Nevertheless, there remains a surprising dearth of knowledge regarding the establishment of an immune response to persistent EBV infection, especially during the incubation period. This lack of knowledge has impaired our ability to develop an effective prophylactic EBV vaccine, despite various attempts. Our greatest challenges in EBV research are to develop a prophylactic vaccine and devise treatment strategies for persons already infected with EBV.

Transplantation of solid organ recipients shedding Epstein-Barr virus DNA pre-transplant: A prospective study.

Epstein-Barr virus (EBV) poses a significant threat to patient and graft survival post-transplant. We hypothesized that recipients who shed EBV at transplant had less immunologic control of the virus and hence were more likely to have active EBV infection and disease post-transplant. To test this hypothesis, we conducted a 5-year prospective study in primary solid organ transplant recipients. We measured EBV DNA in oral washes and blood samples by quantitative PCR before transplant and periodically thereafter for up to 4 years. Pre-transplant samples were available from 98 subjects. EBV DNA was detected pre-transplant in 32 of 95 (34%) and 5 of 93 subjects (5%) in oral wash and blood, respectively. Recipients with and without detectable pre-transplant EBV DNA were not significantly different demographically and had no significant difference in patient and graft survival (P = .6 for both comparisons) or post-transplant EBV viremia-free survival (P = .8). There were no cases of EBV-related disease or post-transplant lymphoproliferative disorder (PTLD) in any of the patients with detectable EBV DNA pre-transplant. In conclusion, detectable EBV DNA pre-transplant was not associated with differences in patient/graft survival, post-transplant EBV viremia, or EBV-related diseases including PTLD.

Kidney transplant after hematopoietic cell transplant in pediatrics: Infectious and immunosuppressive considerations.

Pediatric patients requiring kidney transplant after hematopoietic cell transplant receive multiple courses of immunosuppression placing them at risk for infection. To elucidate potential risk factors for infection, we compared the immunosuppressive regimens and infectious complications of pediatric kidney transplant recipients at a single institution who had previously undergone hematopoietic cell transplant from different donors to similar patients reported in the literature. Among the initial four post-hematopoietic cell transplant kidney transplant patients reviewed, viremia episodes were universal, including BK virus, Epstein-Barr virus, and human herpesvirus-6, with one death from presumed BK virus encephalitis. No viremia was reported in five similar cases in the literature. Risk factors for increased infection include use of lymphodepleting serotherapy in HCT conditioning, multiple HCTs, limited immune reconstitution time between transplants, increased pre-KTx viral burden, and use of T-cell-depleting versus -suppressive induction immunosuppression for KTx. These findings suggest that pediatric post-HCT KTx recipients are at increased risk for viral infections, likely benefitting from thorough pre-KTx evaluation of immune reconstitution and preferential use of non-T-cell-depleting induction therapy for KTx. We applied these recommendations to one subsequent post-HCT patient requiring KTx at our institution with excellent outcomes one year post-KTx.

The impact of donor viral replication at transplant on recipient infections posttransplant: a prospective study.

BACKGROUND: Organ donors are often implicated as the source of posttransplant recipient infection. We prospectively studied kidney and liver donor-recipient pairs to determine if donor viral replication of cytomegalovirus (CMV), Epstein-Barr virus (EBV), and BK polyomavirus (BKV) at transplant was a risk factor for posttransplant recipient infection and disease. METHODS: Donors and recipients were studied for antibodies against CMV and EBV and for quantitative viral replication of CMV, EBV, and BKV in oral washes, urine, and whole blood pretransplant. Recipient testing continued every 3 months after transplantation. Demographic and clinical data on infections and graft and subject outcomes were obtained. RESULTS: The 98 donor-recipient pairs included 15 liver and 83 kidney transplants (18 of whom were children). No donor had detectable CMV replication; therefore, its impact on recipient CMV replication could not be analyzed. Donor EBV replication occurred in 22%, mostly in the oral wash and showed no impact on posttransplant recipient EBV replication (P=0.9) or EBV viremia (P=0.6) in kidney or liver recipients. Donor BKV replication occurred in 17%, mostly in the urine and although not associated with posttransplant recipient urinary BKV replication in recipients, it was associated with BKV viremia (P=0.02), and a significantly shorter time to BKV viremia (P=0.01) in kidney recipients. CONCLUSION: Donor replication of CMV or EBV did not impact posttransplant recipient viral replication in kidney or liver transplants. Donor urinary BKV replication is associated with recipient BKV viremia in kidney transplants.

Valganciclovir administration to kidney donors to reduce the burden of cytomegalovirus and Epstein-Barr virus transmission during transplantation.

BACKGROUND: Cytomegalovirus (CMV) and Epstein-Barr virus (EBV) infections are a significant cause of morbidity and mortality in transplant recipients and are often transmitted from the donor organ. METHODS: In a pilot prospective, randomized, double-blinded, placebo-controlled trial, we studied whether 14 days of pretransplant donor treatment with valganciclovir (valG) versus placebo reduced donor-to-recipient transmission, making posttransplant recipient prophylaxis more effective in reducing EBV and CMV disease. RESULTS: Seventeen D+ R- donor-recipient pairs were enrolled: 7 and 10 donors were randomized to valG and placebo, respectively. At study initiation, no donor had detectable CMV replication, five had EBV replication (two in valG, three in placebo group): EBV replication was undetectable during valG treatment, but resumed on stopping valG. Valganciclovir was tolerated without side effects or leukopenia. All recipients received routine posttransplant viral prophylaxis with valG. For recipients, viremia-free survival time, incidence, range, peak, and duration of CMV and EBV viremia were not significantly different between groups. There was no disease in the valG group but two serious viral diseases occurred in the placebo group (one CMV; one EBV-related posttransplant lymphoproliferative disorder). In the case of posttransplant lymphoproliferative disorder, the EBV DNA from the donor's oral wash and the recipient's lymphoid tissue biopsy had identical latent membrane protein 1 (LMP-1) sequence variations from the reference EBV strain, making it highly probable that the recipient's virus was of donor origin. CONCLUSION: Based on this pilot trial, we recommend an adequately powered study to determine if pretransplant donor treatment with valG can reduce posttransplant CMV and EBV disease with merely routine posttransplant recipient viral prophylaxis.

Suspected piperacillin-tazobactam induced nephrotoxicity in the pediatric oncology population.

Neutropenic fever is a common complication of myelosuppressive therapy in pediatric oncology patients. Piperacillin-tazobactam (PIP/TAZO) is a broad spectrum antibiotic used for empiric treatment of neutropenic fever. We describe four cases of suspected PIP/TAZO induced nephrotoxicity occurring in children with pediatric malignancies admitted to the hospital and treated for fever ± neutropenia. All patients exhibited acute renal injury shortly after PIP/TAZO administration with one of these cases having biopsy evidence of acute interstitial nephritis. These findings are suggestive of PIP/TAZO induced nephrotoxicity in pediatric oncology patients with fever ± neutropenia and that PIP/TAZO should be used judiciously in this population.

Contrast nephropathy in children.

Contrast-induced nephropathy (CIN) remains a common and potentially serious complication in at risk patients after exposure to contrast agents. Risk factors for CIN include chronic kidney disease, hypotension, diabetes mellitus, recent previous exposure to contrast and all of these are potentially additive. Therefore, careful pre-procedural risk stratification is important. In high-risk patients, contrast should be avoided if possible. If avoidance is not possible, the volume of contrast should be minimized and the type of contrast used should if possible be non-ionic iso-osmolar contrast. In view of the clinical importance of CIN, numerous potential risk-reduction strategies have been evaluated. Adequate intravenous volume expansion with isotonic crystalloid (1.0-1.5 mL/kg per hr) for 3-12 hr before the procedure and continued for 6-24 hr afterward can lessen the probability of CIN in patients at risk. But there are insufficient data on oral fluids as a preventive strategy. Nephrotoxic drugs should be withdrawn before contrast administration in patients at risk for CIN. No adjunctive medical or mechanical treatment has been proved to be efficacious in reducing risk for CIN including prophylactic hemodialysis and hemofiltration, N-acetylcysteine, fenoldopam, dopamine, calcium channel blockers, atrial natriuretic peptide, and L-arginine. The CIN Consensus Working Panel considered that, of the pharmacologic agents that have been evaluated, theophylline, 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors (statins), ascorbic acid, and prostaglandin E deserve further evaluation.

Unusual presentations of BK virus infections in pediatric renal transplant recipients.

BKV has emerged as a significant pathogen in the field of transplantation, predominantly causing BKV nephropathy in renal transplant recipients and hemorrhagic cystitis in HSCT recipients. However, case reports describe more diverse complications, and we too present three unusual cases of BKV infections in pediatric renal transplant recipients. First, we describe a case of biopsy-proven renal damage secondary to BKV prior to the onset of viremia, demonstrating that BKV nephropathy can occur without preceding viremia. We also present two renal transplant recipients with persistent BK viruria, one with BKV-associated hemorrhagic cystitis and the other with microscopic hematuria. Therefore, we conclude that BKV manifestations may be more diverse than previously thought and suggest clinical utility in urine BKV qPCR testing in specific transplant recipients.

BK nephropathy in pediatric hematopoietic stem cell transplant recipients.

BK nephropathy is a known cause of renal insufficiency in kidney transplant recipients. Activation of the polyoma virus may also occur in the native kidneys of non-renal allograft recipients. BK nephropathy has only been reported in a few patients after HCT, most being adult patients, and the single reported pediatric case had evidence of hemorrhagic cystitis. The response to antiviral therapy also seems to differ widely. Here, we describe two cases of BK nephropathy in the native kidneys of HCT recipients exposed to high levels of immunosuppression because of GVHD. Neither of our patients had any evidence of hemorrhagic cystitis. We present definitive renal pathology and detailed chronological evidence of the rising serum creatinine with simultaneous serum and urine BK PCR titers. In one of our cases, antiviral therapy did not seem beneficial as documented by continued renal dysfunction and elevated serum/urine BK PCR titers. Based on our report, intense immunosuppression in pediatric HCT recipients seems to be involved in the activation of BK virus and BK nephropathy should be suspected even in the absence of hematuria in HCT recipients with unexplained renal dysfunction.