Early detection of renal damage caused by fumaric acid ester therapy by determination of urinary ß2-microglobulin.

BACKGROUND: Fumaric acid esters are considered efficacious and safe drugs for the treatment of psoriasis. Renal damage, caused either by acute renal injury or Fanconi syndrome, is a recognized side-effect of this therapy. OBJECTIVES: To investigate whether the measurement of urinary excretion of ß2-microglobulin, a marker of renal proximal tubular dysfunction, allows early detection of kidney damage before an increase in serum creatinine or significant proteinuria occurs. METHODS: Urinary ß2-microglobulin excretion was measured regularly in 23 patients undergoing fumaric acid ester therapy. RESULTS: Urinary ß2-microglobulin remained normal in all 10 male patients. Three (23%) out of 13 female patients experienced an increase in urinary ß2-microglobulin excretion. In two of these patients a sharp increase was observed in association with high doses. One further patient had moderately elevated levels on rather low doses of fumaric acid esters. After discontinuing treatment, urinary ß2-microglobulin levels returned to normal within a few weeks. CONCLUSION: Determination of urinary ß2-microglobulin possibly allows early detection of renal damage by fumaric acid esters. Female patients seem to be prone to this side-effect, especially when taking high doses.

Enteric-coated mycophenolate sodium reduces gastrointestinal symptoms in renal transplant patients.

A main cause for gastrointestinal (GI) complications in graft recipients is the routinely administered inosine monophosphate dehydrogenase inhibitor mycophenolic acid (MPA). MPA is available in two formulations, the prodrug mycophenolate mofetil (MMF) and the enteric-coated sodium salt (EC-MPS). Clinical results point to a better GI tolerability of EC-MPS as compared to MMF. We performed an open surveillance study in 397 organ graft recipients to investigate the clinical tolerability of EC-MPS in renal graft recipients who were converted from MMF to EC-MPS (maintenance) or who received EC-MPS as a new component of their immunsuppressive regimen (de novo). Physicians recorded GI symptoms (nausea, emesis, anorexia, diarrhea, abdominal cramps) at the start of EC-MPS treatment (visit 1) and at the next two visits in the clinic (visits 2 and 3); general tolerability (very good/good/moderate/poor) was assessed at visit 2 and 3. Two hundred seventy-five patients were on maintenance treatment with MMF and were converted to equimolar doses of EC-MPS, and 122 patients received EC-MPS de novo. The mean time since transplantation was 4.2 +/- 4.4 years. Median time until visit 2 was 28 days and until visit 3, 65 days. In 63.0% of patients, tolerability was rated as very good at visit 2 and in 64.7% at visit 3. Most patients who had suffered from GI complications during preceding MMF treatment reported improvement or total disappearance of their symptoms after conversion to EC-MPS. In conclusion, EC-MPS is a useful means to reduce GI complications in MPA-treated patients.

Sensitivity and specificity of autoantibody tests in the differential diagnosis of lupus nephritis.

Several studies have investigated the potential of various autoantibody tests in the diagnosis of systemic lupus erythematosus (SLE). Many lupus patients initially present with glomerulonephritis. In that clinical situation the main differential diagnosis are other forms of glomerulonephritis. In this study the diagnostic value of nine test kits for autoantibody against ANA, dsDNA, circulating immune complexes, C1q, nucleosomes, histones and Sm as well as C3 and C4 levels was evaluated in 39 patients with biopsy-proven lupus nephritis in comparison to 43 patients suffering from other forms of glomerulonephritis. The most useful test was an anti-nucleosome antibody enzyme-linked immunosorbent assay (ELISA) with a sensitivity of 90% and a specificity of 88%. All tests for anti-dsDNA antibodies (Crithidia luciliae Anti-dsDNA, BINDAZYME Anti-dsDNA, FARRZYME high avidity Anti-dsDNA) were of moderate sensitivity and very good specificity. Decreasing the cut-off for the conventional anti-dsDNA ELISA (BINDAZYME) considerably increased its sensitivity (87%) without loss of specificity (90%). Tests for anti-C1q and immune complexes performed worse than the antidsDNA tests. As anti-histone and Sm antibodies are present only in a minority of lupus nephritis patients they are of limited value in diagnosing the disease. In conclusion, testing for anti-nucleosome antibodies and the conventional anti-dsDNA ELISA with lower cut-off provide the best diagnostic aids for differentiation of lupus nephritis from other forms of glomerulonephritis.

Familial juvenile hyperuricemic nephropathy: report on a new mutation and a pregnancy.

BACKGROUND: Familial juvenile hyperuricemic nephropathy (FJHN) is a rare autosomal dominant disease caused by mutations in the uromodulin gene (UMOD) and leading to gout, tubulointerstitial nephropathy and end-stage renal disease. CASE REPORTS AND RESULTS: A Latvian family suffering from FJHN is described. The father of the family developed ESRD at age 36. His daughter was diagnosed with gout and chronic kidney disease at age 14 years. A renal biopsy revealed tubulointerstitial disease; 2 sons were diagnosed at age 9 and 4 with elevated uric acid levels and reduced fractional uric acid excretion. Urinary uromodulin was normal in the younger boy, but markedly decreased in the 2 other patients. Genetic analysis revealed a previously undescribed D196Y mutation in the UMOD gene. The female patient became pregnant at age 23. During pregnancy serum creatinine decreased from 2.0 to 1.5 mg/dl and blood pressure remained low. Analysis of the baby's umbilical cord blood and a mouth swab showed the presence of the D196Y mutation. Its urinary uromodulin excretion was in the low normal range. CONCLUSION: The uromodulin excretion pattern observed in the investigated family suggests that urinary uromodulin decreases in FJHN from low normal values at childhood to extremely low levels in early adulthood. In addition, this first report on pregnancy in a patient with FJHN shows normal adaptation despite markedly reduced renal function.

Dislocation of a double-lumen tunneled hemodialysis catheter causing dysfunction and bleeding.

Dislocation of tunneled hemodialysis catheters is rare. This report describes displacement of a split catheter with the tip of the arterial limb outside and the venous limb inside the jugular vein. Use of the catheter with the limbs in inverse fashion caused severe hemorrhage along the catheter tunnel. To avoid this complication, a short subcutaneous catheter tunnel is recommended in adipose patients.

Conversion to enteric-coated mycophenolate sodium from various doses of mycophenolate mofetil: results of a prospective international multicenter trial in maintenance renal transplant patients receiving cyclosporine.

Conversion from mycophenolate mofetil (MMF, CellCept) to enteric-coated mycophenolate sodium (EC-MPS, myfortic) is safe and effective in renal transplant patients treated with the standard dose of 2 g MMF. In this 6-month, international, multicenter, open-label, single-arm trial, a large cohort of maintenance renal transplant patients receiving different doses of MMF were converted under normal clinical conditions to equimolar doses of EC-MPS. Mean calculated creatinine clearance remained stable from the time of study entry (59.6 +/- 19.7 mL/min) to the end of the study (58.3 +/- 19.8 mL/min). Adverse events were reported by 152 patients (67%), with gastrointestinal complications being observed in 45 patients (20%). Thirty-three patients (15%) experienced adverse events or infections with a suspected relation to EC-MPS, including one case of anemia and two cases of leukopenia. Eleven patients (4.9%) required a reduction in EC-MPS dose and seven patients (3.1%) permanently discontinued EC-MPS owing to adverse events. At month 6 after conversion, five patients (2.2%) experienced biopsy-proven acute rejection. There were no graft losses or deaths. These data support earlier findings that stable maintenance renal transplant patients receiving MMF with cyclosporine with or without corticosteroids can be converted to EC-MPS with no compromise in efficacy and tolerability, and no adverse effect on renal function.

Acute inflammatory syndrome induced by mycophenolate mofetil in a patient following kidney transplantation.

Mycophenolate mofetil (MMF) is increasingly used to prevent acute and chronic rejection following kidney transplantation and in autoimmune diseases. Here, we report on a patient after kidney transplantation, who developed an acute inflammatory syndrome characterized by fever and oligoarthritis within 1 week after increasing the MMF dosage. MMF was discontinued resulting in a complete resolution of the syndrome within 48 h. We demonstrated in vitro that the patient's phorbol myristate acetate (PMA-) and formyl Met-Leu-Phe (fMLP-) stimulated polymorphonuclear neutrophils (PMNs) developed increased oxidative burst when incubated with MMF. This report demonstrates that MMF can also induce acute inflammatory syndrome in patients following kidney transplantation and that this syndrome might be due to a paradox, pro-inflammatory reaction of PMNs.

Familial renal glucosuria: SLC5A2 mutation analysis and evidence of salt-wasting.

Familial renal glucosuria (FRG) is an inherited renal tubular disorder characterized by persistent isolated glucosuria in the absence of hyperglycemia. Mutations in the sodium/glucose co-transporter SGLT2 coding gene, SLC5A2, were recently found to be responsible for the disorder. Here, we report the molecular and phenotype study of five unrelated FRG families. Five patients were identified and their family members screened for glucosuria. SLC5A2 coding region of index cases was polymerase chain reaction amplified and sequenced. Five different mutations are reported, including four novel alleles. The IVS12+1G>A and p.A102V alleles were identified in homozygosity in index patients of two unrelated families. A proband from another family was compound heterozygous for the p.R132H and p.A219T mutations, and the heterozygous p.Q167fsX186 frameshift allele was the only mutation detected in the affected individual from an additional pedigree. For the remaining family no mutations were detected. The patient homozygous for the p.A102V mutation had glucosuria of 65.6 g/1.73 m(2)/24 h, evidence of renal sodium wasting, mild volume depletion, and raised basal plasma renin and serum aldosterone levels. Our findings confirm previous observations that in FRG, transmitted as a codominant trait with incomplete penetrance, most mutations are private. In the only patient with massive glucosuria in our cohort there was evidence evocative of renin-angiotensin aldosterone system activation by extracellular volume depletion induced by natriuresis. Definite proof of renin-angiotensin aldosterone system activation in FGR should rely on evaluation of additional patients with massive glucosuria.

Four consecutive renal transplantations in a patient with adenine phosphoribosyltransferase deficiency.

We report a patient with complete adenine phosphoribosyltransferase deficiency and urolithiasis, in whom 4 consecutive cadaveric renal transplantations were performed; 2,8-dihydroxyadenine crystal nephropathy recurred within weeks in the first and second graft when the patient was not treated with allopurinol immediately after transplantation. In the third graft, recurrence of disease could be prevented by immediate allopurinol treatment. This graft was lost due to chronic allograft nephropathy without significant crystal deposition. After a fourth transplantation, again without initial allopurinol, the disease recurred following an initial vascular rejection. Addition of allopurinol significantly improved renal function of the 2nd and 4th graft. This case indicates that outcome of renal transplantation in patients with adenine phosphoribosyltransferase deficiency critically depends on immediate postoperative pharmacotherapy with allopurinol, which is able to prevent 2,8-dihydroxyadenine nephropathy in the graft. Furthermore, rapid recurrence of disease without allopurinol seems to be triggered by delayed graft function and acute rejection.

Cerebral vasculitis in a patient with hereditary complete C4 deficiency and systemic lupus erythematosus.

We describe the case of a female patient with hereditary complete C4 deficiency and systemic lupus erythematosus. She had suffered from lupus nephritis in early childhood. At the age of 23 years she developed severe lupus with skin disease and life-threatening cerebral vasculitis. Her cerebral disease was unresponsive to high-dose steroids, intravenous immunoglobulin, fresh frozen plasma and plasma exchange. Improvement was achieved with immunoadsorption in combination with mycophenolate mofetil. The patient made a complete recovery and is maintained in complete remission on mycophenolate and low-dose steroids.

UROMODULIN mutations cause familial juvenile hyperuricemic nephropathy.

Gout, which is commonly associated with hyperuricemia, affects 0.2% of the population. Hyperuricemia has a heterogeneous etiology that may be due to either over production and/or reduced renal clearance, of urate. In order to identify the mechanisms underlying reduced excretion of urate, we undertook positional cloning studies of familial juvenile hyperuricaemic nephropathy (FJHN), which is an autosomal dominant disorder characterized by hyperuricaemia, a low fractional renal excretion of urate, and chronic renal failure that is associated with interstitial fibrosis. The FJHN locus has been previously localized to a 22 centiMorgan interval flanked centromerically by D16S401 and telomerically by D16S3069, on chromosome 16p11-p13. This interval contains over 120 genes and we selected 13 renal expressed sequences to search for mutations in 5 unrelated FJHN families that contained 21 affected and 24 unaffected members. This revealed 5 heterozygous missense mutations (Cys77Tyr, Cys126Arg, Asn128Ser, Cys255Tyr and Cys300Gly) that altered evolutionary conserved residues in the gene encoding UROMODULIN. UROMODULIN, which is an 85 Kda glycoprotein, has roles in renal stone formation, the modulation of immune responses, and urothelial cytoprotection. The results of our studies, which have identified the gene causing FJHN, now indicate a further, novel role for UROMODULIN in urate metabolism.

Proteinuria and plasma total homocysteine levels in chronic renal disease patients with a normal range serum creatinine: critical impact of true glomerular filtration rate.

Conflicting data have been reported concerning the independent association between proteinuria and plasma total homocysteine (tHcy) levels, particularly among chronic renal disease (CRD) patients with a normal range serum creatinine. Studies of this potential relationship have been limited by failure to assess true GFR, failure to assess proteinuria in a quantitative manner, or arbitrary restriction of the range of proteinuria examined. We examined the potential independent relationship between plasma tHcy levels and a wide range of quantitatively determined proteinuria (i.e., 0.000-8.340 g/day), among 109 CRD patients with a normal range serum creatinine (range; 0.8-1.5 mg/dl; median=1.2 mg/dl). Glomerular filtration rate (GFR) was directly assessed by iohexol clearance, and plasma status of folate, pyridoxal 5'-phosphate, and B12, along with serum albumin, were also determined. Linear modeling with ANCOVA revealed that proteinuria was not independently associated with tHcy levels (partial R=0.127; P=0.201), after adjustment for potential confounding by GFR (partial R=0.408; P<0.001), age, sex, plasma B-vitamin status, and serum albumin. Moreover, descending across quartiles (Q) [from Q4 to Q1] of GFR, ANCOVA-adjusted (i.e., for age, sex, and folate status) geometric mean tHcy levels (micromol/l) were significantly increased: tHcy Q4 GFR=9.6; tHcy Q3 GFR=10.5; tHcy Q2 GFR=11.9; tHcy Q4 GFR=14.5; P<0.001 for overall Q difference. We conclude that across a broad spectrum of quantitatively determined proteinuria, after adjustment for true GFR, in particular, there is no independent relationship between proteinuria and tHcy levels among CRD patients with a normal range serum creatinine.

[Pathogenesis and clinical course of hereditary nephropathies]. / Pathogenese und Klinik hereditärer Nephropathien.

Hereditary diseases have to be considered in the differential diagnosis of many kidney diseases. The kidney can be affected by systemic metabolic diseases such as primary hyperoxaluria or Fabry's disease. Inborn errors of the coagulation cascade or the complement system may cause familiar forms of the hemolytic uremic syndrome. Of central interest are hereditary cystic kidney diseases with autosomal dominant polycystic kidney disease as its most prominent example. Hereditary forms of the nephrotic syndrome are usually caused by abnormalities of podocyte function. Alport's syndrome is a classical example of a basement membrane disease. Of special interest are hereditary defects in tubular transport mechanisms such as carrier defects affecting sodium reabsorption along the tubulus.

Chronic renal transplantation: a model for the hyperhomocysteinemia of renal insufficiency.

Renal transplant recipients (RTR) are considered representative of patients with chronic renal insufficiency (CRI) in general with respect to both reduced, progressively declining renal function, and increased risk for cardiovascular disease (CVD). In accord with this argument, we hypothesized that total (t) plasma concentrations of the putatively atherothrombotic amino acid homocysteine (Hcy) would be equivalent in RTR and CRI patients with comparable renal function. We determined plasma tHcy, folate, pyridoxal 5'-phosphate, and B12 concentrations, in addition to serum creatinine and albumin concentrations, in 86 chronic, stable RTR, and 238 patients with CRI. Within comparable ranges of serum creatinine (i.e. RTR=0.6-4.2 mg/dl; CRI=0.7-4.1 mg/dl), tHcy concentrations did not differ between the two groups (RTR=15.0 micromol/l; CRI=14.9 micromol/l, P=0.899). ANCOVA revealed that renal function, gauged as a simple creatinine measurement, was the major independent determinant of plasma tHcy concentrations, accounting for approximately 80-90% of the total variability in tHcy predicted by the full model (i.e. full model R(2)) containing, in addition to creatinine, the seven other potential explanatory variables. If controlled trials confirm that tHcy-lowering treatment reduces CVD events rates in RTR, these results should be applicable to CRI patients in general.

Pyuria in patients treated with indinavir is associated with renal dysfunction.

BACKGROUND: Indinavir therapy is associated with a continuum of crystal-related syndromes, including nephrolithiasis, renal colic, flank pain without recognizable stone formation, dysuria and asymptomatic crystalluria. A frank nephropathy has been recognized recently as part of the spectrum. METHODS: A retrospective analysis of 72 HIV-infected individuals receiving indinavir was performed to identify the frequency and risk factors for indinavir-associated nephropathy and urinary complications. Individuals treated with nucleoside analogues alone served as controls. RESULTS: Mean serum creatinine levels rose from 1.03 +/- 0.16 mg/dl to 1.11 +/- 0.22 mg/dl at week 12 and 1.15 +/- 0.27 mg/dl at week 24 (both, p < 0.01). Thirteen individuals developed serum creatinine levels > or =1.4 mg/dl. Increased serum creatinine levels were found more frequently in women (p < 0.01) and were associated with pyuria and microhematuria (p < 0.01). Frank renal colic and/or nephrolithiasis (seven patients) and urinary pH were not associated with serum creatinine levels > or =1.4 mg/dl. The mean duration of indinavir treatment, until sterile pyuria occurred, were 22 weeks and 32 weeks until the first rise of serum creatinine levels to > or =1.4 mg/dl. Ten patients showed both findings, pyuria preceded the first rise in serum creatinine levels to > or = 1.4 mg/dl (18 vs. 27 weeks, p = 0.02). Renal biopsy, done in three patients, revealed tubulointerstitial disease with crystals in collecting ducts. In 21 patients, among them 11 with pyuria, indinavir was replaced for various reasons and pyuria disappeared in nine. In these patients mean serum creatinine levels decreased from 1.43 mg/dl at withdrawal of indinavir to 1.04 mg/dl three months later (p < 0.01). CONCLUSION: Indinavir therapy is associated with a decrease in renal function which is reversible after withdrawal. In addition, indinavir-associated tubulointerstitial disease does no in patients taking indinavir may help to identify patients being at risk for nephrotoxicity.