The elevation of the anion gap in steady state chronic kidney disease may be less prominent than generally accepted

BACKGROUND: A presumed cause of metabolic acidosis in chronic kidney disease (CKD) is accumulation of unmeasured anions, leading to a high anion gap (AG). In patients with CKD with a high AG, only minor increases are expected. The aim of this study is to evaluate the magnitude of the AG in documented steady state CKD to examine the effect of CKD on a high-AG metabolic acidosis (HAGMA).METHODS: In this cross-sectional study the AG, bicarbonate, and chloride were evaluated in 1045 blood and urine samples of 501 patients with steady state CKD in the outpatient clinic. The influence of phosphate, albumin and potassium on the AG were evaluated.RESULTS: The mean AG increased from 8.8 mEq/l (±1.57) in CKD stage 1 to 11.2 mEq/l (±2.22) in CKD stage 5 ( P &lt; 0.001). Correction for albumin or phosphate did not influence the magnitude of the AG. Correction for potassium did alter the prevalence of HAGMA, but not the severity. [HCO 3 -] decreased between CKD stages 1 and 5 by 5.1 mEq/l. The [Cl -] increased by 2.6 mEq/l between CKD stages 1 and 5. CONCLUSIONS: The elevation of the AG in patients with steady state CKD is limited and less pronounced than the decrease in [HCO 3 -]. Normal AG metabolic acidosis seems to be more important in CKD than HAGMA. The CKD stage and the magnitude of the AG should be taken into account when evaluating a patient with HAGMA. This study suggests that an AG &gt;15 mEq/l is rarely due to renal failure alone. </p

Oxalate nephropathy in an elderly patient with newly diagnosed celiac disease:a case report

Oxalate nephropathy, due to secondary hyperoxaluria has widely been described in gastrointestinal diseases. However, reports of oxalate nephropathy in newly diagnosed celiac disease are rare. A 72-year-old Caucasian male presented to the hospital with abdominal discomfort and acute renal insufficiency with a creatinine of 290 µmol/L. The clinical course, laboratory results and urinalysis were suspect for tubular injury. Renal biopsy showed calcium oxalate depositions. Elevated plasma and urine oxalate levels established the diagnosis oxalate nephropathy. The abdominal complaints with steatorrhea and positive anti-tissue transglutaminase antibodies were diagnosed as celiac disease, which was confirmed after duodenal biopsies. Treatment with prednisone, and gluten-free, low oxalate and normal calcium diet, lowered the plasma oxalate levels and improved his renal function. Decreased absorption of free fatty acids can lead to increased free oxalate in the colon due to the binding of free fatty acids to calcium, preventing the formation of the less absorbable calcium oxalate in the colon. Oxalate dispositions in the kidney can lead to acute tubular injury and chronic renal insufficiency. Celiac disease is therefore one of the intestinal diseases that can lead to hyperoxaluria and oxalate nephropathy.</p

Predictors of renal flares and long-term renal outcome in patients with lupus nephritis:results from daily clinical practice

OBJECTIVES: To describe renal outcomes of the lupus nephritis (LN) population of the University Medical Centre Groningen (UMCG) in the Netherlands and to identify predictors for renal flares and long-term renal outcome in daily clinical practice. METHODS: A retrospective analysis of biopsy-proven LN patients with induction and maintenance treatment in the UMCG between 1982 and 2016 was performed. Data were collected at time of diagnosis, after 6 months and every year up to 10 years after diagnosis. Outcome measures were renal relapse (biopsy proven), progression to chronic kidney disease (CKD) stage 3 or 4 and chronic renal replacement therapy. The ability of serum creatinine, proteinuria, creatinine clearance, serum anti-double stranded DNA (anti-dsDNA) antibodies, serum complement 3 (C3) and serum complement 4 (C4), as well as biographic data and histopathological class to predict long-term renal outcome was assessed. RESULTS: Seventy-one patients were included, with median follow-up of 120 months (IQR 48-120 months). During follow-up - up to 10 years - twenty-one (30%) patients experienced at least one relapse. Eleven (15%) patients had CKD stage 3 or 4, of whom eight showed persistent CKD since baseline and two (3%) patients required chronic renal replacement therapy. At baseline, low levels of serum C3 were a significant predictor of renal relapse. Low levels of C3 and C4 at 6 and 12 and proteinuria and high levels of anti-dsDNA at 12 months were significant predictors of renal relapse. At baseline, 6 months and 12 months serum creatinine and creatinine clearance were significant predictors for persistent or newly developed CKD 3 or 4, and need for chronic renal replacement therapy. CONCLUSIONS: Almost one-third of LN patients experience at least one renal relapse during long-term follow up, but only 3% need chronic renal replacement therapy. Our data suggests that early serological remission is associated with a low risk of renal relapse. Decreased renal function at onset and the first year after diagnosis is predictive for decreased renal function at a later stage

Staphylococcus aureus and Wegener's granulomatosis

Wegener's granulomatosis (WG) is a form of systemic vasculitis. It is characterized by granulomatous inflammation in the upper and lower airways, vasculitis and necrotizing glomerulonephritis, and is strongly associated with antineutrophil cytoplasmic antibodies against proteinase 3. Since the etiology of the disease is not clear, treatment, consisting of corticosteroids and immunosuppressives, is nonspecific and associated with severe side effects. Pinpointing the trigger(s) of the disease would highly improve treatment. Clinical evidence shows that an infectious agent, the bacterium Staphylococcus aureus, is a risk factor for disease relapse, suggesting its involvement in the pathogenesis of WG. Here we review both clinical and experimental data that either indicate or support a role for S. aureus in WG

Goodpasture’s Syndrome with Negative Anti-glomerular Basement Membrane Antibodies

A young male patient with rapidly progressive and life-threatening pulmonary haemorrhage due to anti-glomerular basement membrane (anti-GBM) antibody disease without renal involvement repeatedly tested negative for serum anti-GBM antibodies. Although rare, antiGBM antibody disease should be considered in the differential diagnosis in patients with life-threatening pulmonary haemorrhage due to isolated diffuse alveolar haemorrhage. Enzyme-linked-immunosorbent assay (ELISA) testing for anti-GBM antibodies in anti-GBM antibody disease can give false-negative results. A negative serum anti-GBM antibody test is therefore insufficient to exclude the diagnosis. Thus, a kidney or lung biopsy should be considered in any case with a high clinical suspicion but negative anti-GBM antibody test to confirm or rule out the diagnosis

Regulatory and effector B cell cytokine production in patients with relapsing granulomatosis with polyangiitis

Background: B cells are capable of producing regulatory and effector cytokines. In patients with granulomatosis with polyangiitis (GPA), skewing of the pro- and anti-inflammatory cytokine balance may affect the risk of relapse. This study aimed to investigate differences in B cell cytokine production in patients with relapsing GPA and in controls, and determine whether this can aid in relapse prediction. Methods: Thirteen GPA patients with an upcoming relapse were matched with non-relapsing patients and healthy controls in a retrospective design. The B cell subset distribution was determined from peripheral blood. Cryopreserved peripheral blood mononuclear cells were cultured and intracellular B cell production of regulatory (IL10) and effector (TNF alpha, IFN gamma IL2, IL6) cytokines was assessed. Finally, serum markers associated with B cell activation (sCD27) and migration (CCL19) were determined. Results: GPA patient samples exhibited significantly lower percentages of TNF alpha+B cells than controls, an effect that was most pronounced in patients about to relapse. B cell capacity for IL10 production was similar in patients and controls. No significant differences were observed for cytokine production in relapsing and non-relapsing GPA patients. TNFa production correlated strongly with IL2, IFN gamma and the percentage of memory B cells. No change in effector cytokines occurred before relapse, while the percentage of IL10+B cells significantly decreased. GPA patients in remission had increased serum levels of CCL19 and sCD27, and sCD27 levels increased upon active disease. Conclusions: While differences in effector B cell cytokine production were observed between patients and controls, monitoring this in GPA did not clearly distinguish patients about to relapse. Prospective measurements of the regulatory cytokine IL10 may have potential for relapse prediction. Memory B cells appear mainly responsible for effector cytokine production. Increased migration of these cells could explain the decreased presence of TNF alpha+B cells in the circulation