Portuguese Journal of Nephrology & Hypertension

Oxalate nephropathy following Roux-en-Y gastric bypass surgery - Mini-Review

Oxalate Nephropathy is characterised by the presence of tubular crystalline deposits of calcium oxalate, which can lead to both acute and chronic tubular injury and progressive renal failure. Enteric hyperoxaluria is the most common cause of moderate hyperoxaluria; it occurs in conditions associated with fat or bile acid malabsorption, which include jejunoileal bypass and other bariatric procedures such as Roux-en-Y gastric bypass surgery. We present the clinical case of a 69-year-old man who was hospitalised for non-oliguric renal dysfunction, with a serum creatinine of 10 mg/dl and normocytic normochromic anaemia. There was no prior history of renal disease. Twenty months before admission the patient was diagnosed with a gastro-oesophageal junction adenocarcinoma and was treated with pre-operative chemotherapy, followed by total gastrectomy, with a Roux-en-Y gastric bypass reconstruction. On discharge from gastric surgery, renal function was normal. On the first day of hospital stay haemodialysis was initiated. Over the following days, the rapid unexplained renal impairment was investigated, and this workup [2] included a kidney biopsy. Histological examination of the biopsy specimen revealed a predominantly interstitial nephropathy with tubular atrophy and interstitial fibrosis, with bright intra-tubular calcium oxalate crystals in over 50% of the tubules and so the histological diagnosis was of oxalate nephropathy. Subsequently, no recovery of renal function was observed, so the patient is currently undergoing regular haemodialysis. Oxalate nephropathy is a rare but severe complication of Roux-en-Y gastric bypass surgery that can lead to a rapid progression to kidney failure. Although the treatment of obesity is the main indication for this surgery, this is also the preferred approach for gastrointestinal reconstruction after total gastrectomy for treatment of gastric carcinoma. Considering the rapid progression of oxalate nephropathy to kidney failure, patients who undergo Roux-en-Y gastric bypass surgery should have regular follow-up of renal function.

Implications for patients waiting for a kidney transplant of using the calculated panel reactive antibody (cPRA)

Introduction: Kidney transplant improves survival even in highly-sensitized(HS) patients. To overcome their disadvantage in accessing transplantation, those with high Complement Dependent Cytotoxic PRA (CDC-PRA) receive additional points during allocation. Whether this strategy reaches all HS patients and how long they wait for a transplant is largely undetermined. Methods: Patients on our units active wait-list for kidney transplantation in the year 2014 were analyzed. CDC-PRA and calculated PRA (cPRA) were recorded. To obtain cPRA, antibodies in the last serum available specific for HLA-A,-B or -DR with an intensity > 1000 MFI were considered. Results: The cPRA values in the population (N=551) were 0% (N=312), 1-79% (N=118) and ≥ 80% (22%; N=121). Among these groups, the proportion of women (29.5, 55.9 and 61.2%, P<0.001), prior sensitizing events (43.3, 80.5 and 96.7%, P<0.001) and time on dialysis (median of 3.9, 4.1 and 6.0 years, P<0.001) increased with cPRA, respectively. In most of those with a cPRA ≥ 80%, the CDC-PRA raised no suspicion of HS status (median 0%, P25-75 0-8%) and only 35 (28.9%) or 12 patients (9.9%) had a CDC-PRA in the peak serum higher than 50 or 80%, respectively (cut-offs needed to obtain additional points during allocation). HS patients by cPRA corresponded to 71% vs 15% of patients waiting for ≥ or <8 years, respectively (P<0.001). Even after exclusion of patients with a CDC-PRA above 50%, this disproportionate representation remained (58% versus 13%, P<0.001). Conclusion: HS patients as measured by cPRA remained longer on the wait-list, both in the primary analysis and when excluding those with a CDC-PRA> 50%. Moreover, only 30% of HS by cPRA patients received the extra points designed to improve their transplantability. We consider that both CDC-PRA and cPRA should be taken into account when defining HS status

Serum levels of TNF-α, IL-6 and IL-10 in haemodialysis and renal transplant patients and in healthy subjects

Background: Inflammatory processes seem to play an important role in the development of atherosclerosis. Recurrent or chronic inflammatory processes are common in individuals with end-stage renal disease. There isno consensus approach to assess the degree of severity of inflammation in individuals with kidney disease. In recent years, there has been a growing interest in the role of various cytokines in chronic kidney disease (CKD). Cytokines such as tumor necrosis factor-alpha (TNF-α) and interleukin 6 (IL-6) are mediators of inflammation that may play an important role in CKD. Interleukin 10 (IL-10) is a regulatory cytokine that seems to play a role in limiting inflammatory processes. Aim: The aim of this study was to evaluate the serum levels of TNF- α, IL-6 and IL-10 in a population of haemodialysis and renal transplant patients and in healthy subjects. Methods: This was a cross-sectional study. In 152 participants inflammation was assessed by measuring TNF-α, IL-6 and IL-10. The study included 53 haemodialysis patients, 45 renal transplant patients and 54 healthy subjects. Results: Serum levels of TNF-α were significantly higher in haemodialysis and renal transplant patients than in healthy subjects (40.2±10.8 vs 5.2±1.7 pg/mL; p<0.05; and 16.1±5.9 vs 5.2±1.7 pg/mL; p<0.05, respectively). Serum levels of IL-6 were significantly higher in haemodialysis patients than in healthy subjects (40.2±41.4 vs 16.4±5.4 pg/mL; p<0.05), whereas no significant difference was found between renal transplant patients and healthy subjects (20.1±8.3 vs 16.4±5.4 pg/mL; p=NS). Serum levels of IL-10 were significantly higher in haemodialysis and renal transplant patients than in healthy subjects (23.8±4.5 vs 10.5±3.9 pg/mL; p<0.05; and 19.4±3.1 vs 10.5±3.9 pg/mL; p<0.05, respectively). Conclusion: This study showed higher levels of inflammatory markers (TNF-α, IL-6) and of the regulatory cytokine IL-10 in haemodialysis patients than in healthy controls and higher levels of TNF-α and IL-10 in renal transplant patients than in healthy controls. In haemodialysis patients, increased levels of inflammatory markers usually predict a poor outcome

Aldosterone levels in patients on haemodialysis: Relationship with body fat mass and adipocytokines

Background: It has been recently shown that serum aldosterone (SA) levels are correlated with insulin resistance, excess body fat and levels of adipocytokines. Aim: To establish SA levels in patients on haemodialysis (HD) and the possible association with excess body fat and/or serum adipocytokine levels. Methods: 28 stable patients on HD. Mean age: 73.7±13.3 years; 53.6% men. Mean time on HD: 40.2± 40.8 months. None were diabetics nor treated with drugs that interfere with the renin-angiotensin-aldosterone-system. 18 patients were anuric. All measurements were performed prior to the midweek HD session. Results: SA levels (median: 28.1; 25th percentile (p25):10.4; 75th percentile (p75):98.6 ng/dl) were above the normal range in 53.6% of patients. Plasma renin activity (PRA) (median: 1.05; p25: 0.16; p75: 3.1 ng/mL/hour) was above the normal range in 21.4% of patients. There were no statistically significant differences in SA levels between anuric and non-anuric, male and female, presence and absence of myocardiopathy. There were no statistically significant correlations of SA levels or PRA with urine volume, residual renal function, dose or time on dialysis. age, or comorbidity. SA levels were positively correlated with PRA (r=000.70; p< 0.0001); body fat mass (r=0.40; p=0.03); leptin (r=0.45; p =0.01); leptin/adiponectin ratio (r=0.52 p=0.005) and negatively with serum adiponectin levels (r=- 0.37; p=0.05). In stepwise multiple regression analysis, the best model to explain SA levels included PRA and LAR (r=0.78; r2=0.60). Conclusions: SA levels were elevated in a high percentage of HD patients. SA levels were correlated with PRA, body fat mass and adipocytokines

Malignancy after renal transplantation: a single-centre experience

Introduction: Malignancy management in renal transplant recipients is becoming a major factor affecting long-term patient survival. Thus, we intended to evaluate both incidence and prognosis of malignant diseases following renal transplantation at a single centre in Portugal. Methods: We studied retrospectively the 2,358 patients who underwent kidney transplantation (KT) between 1983 and 2014. Apart from descriptive analysis, both demographic and clinical characteristics of cancer and non-cancer cancer patients were compared. Results: During a median follow-up of 118 (IQR 57-179) months, 139 patients (5.8%) developed 158 de novo malignancies, with a median time from KT to diagnosis of 76..5 (IQR 21.0-132.0) months. When compared to non-cancer patients, they were older at KT date, had longer graft survival and a lower living donor recipients prevalence. As for post-transplant malignancies analysis, the most common were non-cutaneous non-lymphomatous cancers (49.4%, n=78), skin cancers (35.4%, n=56) and post-transplant lymphoproliferative disorders (9.5%, n=15). Considering specific diagnosis, squamous cell carcinoma and basal cell carcinoma with 17.1% and 16.5% respectively, and non-Hodgkin lymphomas with 7.6%, were the most frequent. Global mortality among cancer patients was 36.0%, with a median time of 9.7 (IQR 1.9-17.5) months from time of diagnosis to death. As for survival analysis, cancer patient survival was significantly lower while censored graft survival was significantly higher in this group. Conclusion: Incidence and characteristics of malignancy following renal transplantation in our unit are similar to those globally described, despite some traits probably a result of specific ethnic and environmental characteristics

Chronic myelomonocytic leukaemia: a presentation with rare extramedullary involvement

A 74-year-old male with a recent diagnosis of chronic myelomonocytic leukaemia (CMML) was admitted for rapidly progressive renal failure (RPRF), associated with gait impairment due to muscle weakness and pain in the lower limbs. After exclusion of pre-renal and post-renal causes of RPRF, the workup revealed monocytosis, high levels of inflammatory markers, hypergammaglobulinaemia, nephrotic proteinuria and high serum and urinary lysozyme levels. Renal biopsy confirmed the diagnosis of lysozyme-induced kidney injury and CMML-associated vasculitis. An electromyogram also revealed sensorimotor axonal polyneuropathy. The patient was started on prednisolone and azacitidine. Improvement of limb symptoms and a decrease in monocyte count, renal function values, inflammatory markers and proteinuria were subsequently seen. Although lysozyme levels are consistently elevated in CMML, lysozyme-induced kidney injury is a rare cause of renal failure. Filtered lysozyme appears to act as a direct tubular toxin and lysozymuria has been proposed as a valuable tool for detection of tubular damage. Polyneuropathy secondary to CMML is also infrequent and may be due to autoimmune mechanisms. We describe a case of lysozyme-induced kidney injury, vasculitis and axonal polyneuropathy, presumably secondary to CMML, in which prednisolone and azacitidine seem to have been helpful in treating extramedullary leukaemic involvement

Hemodialysis Reliable Outflow (HeRO) Graft device: a lifesaving solution in multiple vascular access failure in haemodialysis patients

The increasing prevalence of end-stage chronic kidney disease associated with advances in treatment is expected to lead to improved survival rates of chronic haemodialysis patients in Portugal. Establishing and maintaining vascular access patency is becoming a challenging issue in these patients. We present a case report of a multiple vascular access failure patient to whom a novel vascular access device was implanted which allowed successful haemodialysis, despite the presence of central venous stenosis and/or occlusion. To our knowledge the present case report describes the first utilization of Hemodialysis Reliable Outflow (HeRO) Graft device in Portugal. We present the case as well as a brief description of the device and available literature. This case report also underlines the importance of adopting a multidisciplinary approach in order to overcome complex and life-threatening clinical challenges

Fever of unknown origin and pericardial effusion in a haemodialysis patient

Introduction: Retroperitoneal fibrosis is a rare disorder. The idiopathic (IRF) form of the disease accounts for most of cases. Renal failure is a common finding, and some patients present with non-functioning kidneys, as a result of long-lasting obstructive uropathy. The symptoms and signs associated with IRF are non-specific and, thus, its diagnosis requires a high degree of suspicion. Case Report: A 71-year-old man with multifactorial chronic kidney disease required initiation of haemodialysis on February 2014, due to disease progression to end-stage renal disease (ESRD). His past medical history included the diagnosis of optic neuritis, seronegative arthritis and biopsy-proven retroperitoneal fibrosis. The patient had been treated with glucocorticoids for 13 years, stopping this treatment at the time of haemodialysis (HD) initiation. Two months after initiation of HD, in April 2014, the patient complained of malaise and presented with recurrent fever. A thorough clinical and laboratory evaluation was unremarkable. An echocardiogram showed a minor to moderate pericardial effusion that led to prescription of HD intensification. Five months later, he was admitted to the Hospital due to worsening of the pericardial effusion, requiring pericardiocentesis. Pericardial fluid analysis showed exudative changes. A thorough laboratory evaluation was performed and only interferon gamma release assay (IGRA) was positive. Empirical anti-bacillary therapy was initiated, waiting for definite mycobacterial cultures. One month later, as the patient maintained complains of malaise and fatigue, and had recurrent fever, he was readmitted to the Hospital. Mycobacterial cultures ultimately became negative. Further work-up was performed, including positron emission tomography/computed tomography (PET/CT) scan, which detected recurrence of IRF along with aortic, pericardial and pleural involvement. Following initiation of glucocorticoid treatment, a clinical and laboratoryl improvement was documented, that persisted at 11 months of follow-up. Conclusion: IRF is characterized by a relapsing nature, and clinical presentation includes local and systemic symptoms and complications, making it difficult to diagnose. Treatment of IRF is often delayed because of difficulties in reaching the correct diagnosis