Increased Glomerular Filtration Rate in Early Stage of Balkan Endemic Nephropathy.

Background: A previous study indicated that Balkan endemic nephropathy (BEN) patients in the early stage of the disease had significantly higher creatinine clearance (Ccr) than healthy persons. The aim of the study was to assess whether tubular creatinine secretion affects Ccr in early stages of BEN and to check the applicability of serum creatinine-based glomerular filtration rate (GFR) equations in these patients. Methods: The study involved 21 BEN patients with estimated GFR (eGFR) above 60 mL/min/1.73 m2, excluding any conditions that could affect GFR or tubular creatinine secretion, and 15 healthy controls. In all participants Ccr with and without cimetidine and iohexol clearance (mGFR) were measured and eGFR calculated using Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) and Modification of Diet in Renal Disease Study (MDRD) equations. Glomerular hyperfiltration cutoff (GFR-HF) was calculated. Results: There was no significant difference between the groups in Ccr before and after cimetidine or for eGFR, but mGFR was significantly higher in BEN patients than in controls (122.02 ± 28.03 mL/min/1.73 m2 vs. 101.15 ± 27.32 mL/min/1.73 m2; p = 0.032). Cimetidine administration reduced Ccr by 10% in both groups. The ratio of Ccr to mGFR was significantly above one in seven BEN patients and five controls and their mGFR values were similar. Seven other patients and eight controls had this ratio equal to one, while values below one were recorded for seven more patients and two controls. mGFR of all these 14 patients was significantly higher than that of healthy controls (129.88 ± 27.52 mL/min/1.73 m2 vs. 107.43 ± 19.51 mL/min/1.73 m2; p = 0.009). Mean GFR-HF was significantly higher than mGFR in controls, but these two values were similar in BEN patients. eGFR underestimated mGFR in both BEN patients and controls. Conclusion: The ratio of Ccr to mGFR and mGFR to GFR-HF indicated that elevated mGFR in early stages of BEN could be explained by increased glomerular filtration, but tubular creatinine secretion augmented Ccr in a smaller proportion of patients, who did not differ from healthy subjects.

Association of SOD2 (rs4880) and GPX1 (rs1050450) Gene Polymorphisms with Risk of Balkan Endemic Nephropathy and its Related Tumors.

Background: Experimental data show that superoxide dismutase 2 (SOD2) is involved in ochratoxin (OTA)-induced nephrotoxicity, whereas clinical data indicate the role of SOD2 rs4880 or glutathione peroxidase 1 (GPX1) rs1050450 polymorphisms in end-stage renal disease and urothelial carcinoma risk, known to be the major complications of Balkan endemic nephropathy (BEN). Therefore, we hypothesized that SOD2 and GPX1 gene polymorphisms would influence the risk of BEN and its associated tumors. Materials and Methods: The study was conducted in 207 BEN patients and 86 controls from endemic areas. Results: Individuals with both copies of variant SOD2 allele, known for lower mitochondrial antioxidant protection, are at a significantly higher BEN risk (OR = 2.6, p = 0.021). No association was observed between GPX1 gene polymorphism and BEN risk. Combining SOD2 and GPX1 genotypes did not alter the risk of BEN development. Regarding the risk of urothelial tumors in BEN patients, none of the polymorphisms studied was significantly associated with the risk of these tumors. Conclusions: Polymorphism in SOD2 rs4880 gene affects the risk of BEN development. Hence, SOD2 genotyping could, together with a panel of other enzymes, be used as a biomarker of susceptibility in BEN areas.

Balkan endemic nephropathy: an update on its aetiology.

Balkan endemic nephropathy (BEN) is a unique, chronic renal disease frequently associated with upper urothelial cancer (UUC). It only affects residents of specific farming villages located along tributaries of the Danube River in Bosnia-Herzegovina, Croatia, Macedonia, Serbia, Bulgaria, and Romania where it is estimated that ~100,000 individuals are at risk of BEN, while ~25,000 have the disease. This review summarises current findings on the aetiology of BEN. Over the last 50 years, several hypotheses on the cause of BEN have been formulated, including mycotoxins, heavy metals, viruses, and trace-element insufficiencies. However, recent molecular epidemiological studies provide a strong case that chronic dietary exposure to aristolochic acid (AA) a principal component of Aristolochia clematitis which grows as a weed in the wheat fields of the endemic regions is the cause of BEN and associated UUC. One of the still enigmatic features of BEN that need to be resolved is why the prevalence of BEN is only 3-7 %. This suggests that individual genetic susceptibilities to AA exist in humans. In fact dietary ingestion of AA along with individual genetic susceptibility provides a scenario that plausibly can explain all the peculiarities of BEN such as geographical distribution and high risk of urothelial cancer. For the countries harbouring BEN implementing public health measures to avoid AA exposure is of the utmost importance because this seems to be the best way to eradicate this once mysterious disease to which the residents of BEN villages have been completely and utterly at mercy for so long.

Familial versus environmental factors in Balkan endemic nephropathy in Mehedinti county, Romania, by means of albuminuria and tubular biomarkers: preliminary study.

INTRODUCTION AND AIMS: Balkan endemic nephropathy (BEN), a regional tubulointerstitial kidney disease encountered in South-Eastern Europe, with still undefined etiology and inexorable evolution towards end stage renal disease, raises the question of the relative contribution of family and environmental factors in its etiology. In order to evaluate the intervention of these factors, markers of tubular injury have been assessed, this lesion being considered an early renal involvement in BEN. METHODS: The paper studies relatives of BEN patients currently included in dialysis programmes (for involvement of the family factor) and their neighbors (for involvement of environmental factors) and analyzes them with regard to tubular injury by means of tubular biomarkers (N-acetyl-beta-d-glucosaminidase-NAG and alpha-1-microglobulin), and albuminuria. At the same time, glomerular filtration rate (GFR) (CKD-EPI) was measured. It is considered that, in order to acquire the disease, one should have lived for 20 years in the BEN area. The relatives have been classified according to this criterion. RESULTS: More evident tubular injury was found in the neighbors of BEN patients living for more than 20 years in the endemic area, which argues in favor of environmental factors. Higher levels of urinary alpha-1-microglobulin and albumin in relatives of BEN patients who had been living for more than 20 years in the area than in relatives with a residence under 20 years, plead for the same hypothesis. GFR was lower in persons who had been living for more than 20 years in the BEN area (neighbors and relatives). CONCLUSIONS: Environmental factors could be more important in BEN than family factors.

Prognostic value of Balkan endemic nephropathy and gender on upper tract urothelial carcinoma outcomes after radical nephroureterectomy: A cohort study.

BACKGROUND: To identify the prognostic impact of residence in a BEN-endemic area and gender on upper tract urothelial carcinoma (UTUC) outcomes in Serbian patients treated with radical nephroureterectomy (RNU). METHODS: The study included 334 consecutive patients with UTUC. Patients with permanent residence in Balkan endemic nephropathy (BEN) or non-endemic areas from their birth to the end of follow-up were included in the analysis. Cox regression analyses were used to address recurrence-free (RFS) and cancer-specific survival (CSS) estimates. RESULTS: Female patients were more likely to have preoperative pyuria (P = 0.01), tumor multifocality was significantly associated with the female gender (P = 0.003). Gender was not associated with pathologic stage and grade, lymph node metastasis, lymphovascular invasion, adjuvant chemotherapy, bladder cancer history, tumor size, distribution of tumor location, preoperative anemia and demographic characteristics. A total of 107 cases recurred, with a median time to bladder recurrence of 24.5 months. History of bladder tumor (HR, 1.98; P = 0.005), tumor multifocality (HR, 3.80; P < 0.001) and residence in a BEN-endemic area (HR, 1.81; P = 0.01) were independently associated with bladder cancer recurrence. The 5-year bladder cancer RFS for the patients from areas of BEN was 77.8 % and for the patients from non-BEN areas was 64.7 %. The 5-year CSS for the men was 66.2% when compared to 66.6% for the women (P = 0.55). CONCLUSIONS: Residence in a BEN-endemic area represents an independent predictor of bladder cancer recurrence in patients who underwent RNU. Gender cannot be used to predict outcomes in a single-centre series of consecutive patients who were treated with RNU for UTUC.

Fifty years of Balkan endemic nephropathy: challenges of study using epidemiological method.

Balkan endemic nephropathy (BEN) is a chronic tubulointerstitial disease associated with urothelial cancer, which affects people living in the alluvial plains along the tributaries of the Danube River. Challenges of studying BEN using the epidemiological method are multiple. The natural history from exposure to occurrence of the disease may take many years. The early stages of BEN are not easily detectable clinically, as the disease is asymptomatic until a significant decline in function occurs, and even then symptoms are usually non-specific. The natural history of BEN is complex, possibly with multiple risk factors operating both at the stage of initiation of renal damage and in its progression. In BEN, genetic susceptibility is due to multiple genes of small effects, gene-gene interactions, and gene-environment interactions of complex nature that are difficult to assess with current study designs. BEN is now kidney disease of the old people, and many risk factors for disease such as smoking, alcohol consumption, obesity, and diabetes could contribute to the kidney damage. Evidence is presented that environmental rather than genetic factors play a decisive role in the etiopathogenesis of BEN. Aristolochic acid, described as a culprit of BEN in 1959, is confirmed in 2007 by the molecular biology methods. Mycotoxins and polycyclic aromatic hydrocarbons, leached from lignites and found in the vicinity of endemic settlements, deserve further investigation. Despite advances in understanding the epidemiology of BEN, more research is needed on the patterns of BEN over time and between places, and on identifying the contributions of modifiable risk factors in initiating and hastening progression of BEN in order to improve the scope for preventing BEN. Primary prevention is still at the beginning. Knowledge accumulated in the fifty years of BEN research and new data about prevention and treatment of chronic kidney disease reveal several effective methods in secondary and tertiary prevention of BEN. Genetic epidemiology could establish the relative size of the genetic effect in relation to other sources of variation in disease risk (i.e., environmental effects such as intrauterine environment, physical and chemical effects, as well as behavioral and social aspects). Public health authorities in the several countries having aristolochic acid nephropathy should take immediate measures for reducing dietary exposure of residents to Aristolochia.

Visual assessment of endemic nephropathy markers relationship.

The aim of this paper was to assess relationship between possible endemic nephropathy (EN) markers visually by the CoPlot methodology, and to illustrate this promising data analysis approach. From 912 screened persons in 3 Croatian endemic villages, 25 persons were diagnosed as confirmed EN patients, 371 as non-EN, and the remainder were classified as suspected of having EN, or at risk. Data on 25 confirmed EN patients were matched with appropriate non-EN examinees. All records with missing data were excluded, resulting in 35 subjects with complete data on the 13 key EN variables for CoPlot mapping. CoPlot solution met the accepted goodness of fit measure thresholds. Result showed relationship between EN markers, identifying some nearly duplicated variables, and possible outliers needing some subsequent analysis.

Increased blood pressure in adult offspring of families with Balkan endemic nephropathy: a prospective study.

BACKGROUND: Previous studies have linked smaller kidney dimensions to increased blood pressure. However, patients with Balkan Endemic Nephropathy (BEN), whose kidneys shrink during the course of the disease, do not manifest increased blood pressure. The authors evaluated the relationship between kidney cortex width, kidney length, and blood pressure in the offspring of BEN patients and controls. METHODS: 102 offspring of BEN patients and 99 control offspring of non-BEN hospital patients in the Vratza District, Bulgaria, were enrolled in a prospective study and examined twice (2003/04 and 2004/05). Kidney dimensions were determined using ultrasound, blood pressure was measured, and medical information was collected. The parental disease of BEN was categorized into three groups: mother, father, or both parents. Repeated measurements were analyzed with mixed regression models. RESULTS: In all participants, a decrease in minimal kidney cortex width of 1 mm was related to an increase in systolic blood pressure of 1.4 mm Hg (p = 0.005). There was no association between kidney length and blood pressure. A maternal history of BEN was associated with an increase in systolic blood pressure of 6.7 mm Hg (p = 0.03); paternal BEN, +3.2 mm Hg (p = 0.35); or both parents affected, +9.9 mm Hg (p = 0.002). There was a similar relation of kidney cortex width and parental history of BEN with pulse pressure; however, no association with diastolic blood pressure was found. CONCLUSION: In BEN and control offspring, a smaller kidney cortex width predisposed to higher blood pressure. Unexpectedly, a maternal history of BEN was associated with average increased systolic blood pressure in offspring.

Biomarkers of oxidative damage and antioxidant enzyme activities in pre-dialysis Balkan endemic nephropathy patients.

AIM: To obtain more insight into molecular mechanisms underlying oxidative stress in Balkan endemic nephropathy (BEN), biomarkers of oxidative stress and antioxidant enzyme activities were studied in 38 pre-dialysis BEN patients, 21 healthy BEN family members and 36 healthy subjects from non-endemic areas. METHODS: Protein thiol groups (P-SH), antioxidant enzyme activities [superoxide dismutase (SOD) and glutathione peroxidase (GPX)], were determined in plasma spectrophotometrically, while malondialdehyde adducts (MDA) by enzyme immunoassay. RESULTS: BEN patients had significantly lower plasma GPX activity in comparison with values for both control groups (p = 0.016), gradually decreasing with kidney function impairment estimated by glomerular filtration rate (r = 0.53, p = 0.002). GPX activity was inversely correlated with serum urea (r = -0.627, p < 0.001), creatinine (r = -0.53, p < 0.05), urinary excretion of protein and α1-microglobulin (r = -0.44, p = 0.012; r = -0.50, p < 0.007). Significant upregulation of SOD activity was observed in healthy BEN family members (p < 0.05). While the concentration of MDA adducts was similar in all three groups, BEN patients and healthy BEN family members exhibited increased protein damage, based on fewer P-SH groups in comparison with subjects from non-BEN areas (p = 0.085; p = 0.014, respectively). CONCLUSIONS: Based on our results on increased oxidative protein damage in both pre-dialysis BEN patients and healthy BEN family members, it can be speculated that individuals from BEN areas, in general, are chronically exposed to some prooxidant environmental compounds. Moreover, decrease in plasma GPX activity, as a consequence of impaired kidney function, could further affect oxidative status in BEN patients.

Prevalence and risk factors of vascular calcification in pre-dialysis patients with Balkan endemic nephropathy.

Introduction: Vascular calcifications (VC) are common in patients with chronic kidney disease and present one of manifestations of mineral and bone disorders in these patients. Objective: The aim of this pilot study was to examine the prevalence and risk factors of VC in pre-dialysis patients with Balkan endemic nephropathy (BEN) and other kidney diseases. Methods: The study involved 32 pre-dialysis patients, 15 with BEN and 17 with other kidney diseases. All the patients underwent an interview, objective examination, routine laboratory analyses and measurement of serum concentration of intact parathyroid hormone (iPTH), 25-hydroxyvitamin D3 [25(OH)D3] and osteopontin. VCs in iliac, femoral, radial, and digital arteries were evaluated and Adragao VC score was calculated. The samples of radial artery were collected during the first creation of an arteriovenous fistula, and expression of osteocalcin, bone morphogenic protein-2 osteopontin, and matrix Gla-protein in arterial wall were examined. Results: Patients with BEN were significantly older (71.1 ± 6.1 vs. 54.7 ± 11.1 years), but they had significantly lower systolic and mean blood pressure (95.7 ± 13.2 mmHg vs. 104.3 ± 7.4 mmHg) and lower serum concentration of phosphorus (1.32 ± 0.36 mmol/l vs. 1.65 ± 0.35 mmol/l) and cholesterol (4.3 ± 1.1 mmol/l vs. 5.2 ± 0.8 mmol/l) than patients with other kidney diseases. Mean VC score was significantly lower in patients with BEN than in those with other kidney diseases (2.8 ± 1.7 vs. 4.6 ± 1.8; p = 0.009), but expression of four examined proteins in arterial wall differed insignificantly between the two groups. VC score correlated significantly with serum concentrations of cholesterol, triglycerides (positively), and iPTH (negatively). Conclusion: Pre-dialysis BEN patients had a significantly lower mean score of VC than patients with other kidney diseases.

Chronic dietary exposure to aristolochic acid and kidney function in native farmers from a Croatian endemic area and Bosnian immigrants.

BACKGROUND AND OBJECTIVES: Improvements in agricultural practices in Croatia have reduced exposure to consumption of aristolochic acid-contaminated flour and development of endemic (Balkan) nephropathy. Therefore, it was hypothesized that Bosnian immigrants who settled in an endemic area in Croatia 15-30 years ago would be at lower risk of developing endemic nephropathy because of reduced exposure to aristolochic acid. To test this hypothesis, past and present exposure to aristolochic acid, proximal tubule damage as a hallmark of endemic nephropathy, and prevalence of CKD in Bosnian immigrants were analyzed. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS: In this cross-sectional observational study from 2005 to 2010, 2161 farmers were divided into groups: indigenous inhabitants from endemic nephropathy and nonendemic nephropathy villages and Bosnian immigrants; α-1 microglobulin-to-creatinine ratio >31.5 mg/g and eGFR<60 ml/min per 1.73 m(2) were considered to be abnormal. RESULTS: CKD and proximal tubule damage prevalence was significantly lower in Bosnian immigrants than inhabitants of endemic nephropathy villages (6.9% versus 16.6%; P<0.001; 1.3% versus 7.3%; P=0.003, respectively); 20 years ago, Bosnian immigrants observed fewer Aristolochia clematitis in cultivated fields (41.9% versus 67.8%) and fewer seeds among wheat seeds (6.1% versus 35.6%) and ate more purchased than homemade bread compared with Croatian farmers from endemic nephropathy villages (38.5% versus 14.8%, P<0.001). Both Croatian farmers and Bosnian immigrants observe significantly fewer Aristolochia plants growing in their fields compared with 15-30 years ago. Prior aristolochic acid exposure was associated with proximal tubule damage (odds ratio, 1.64; 95% confidence interval, 1.04 to 2.58; P=0.02), whereas present exposure was not (odds ratio, 1.31; 95% confidence interval, 0.75 to 2.30; P=0.33). Furthermore, immigrant status was an independent negative predictor of proximal tubule damage (odds ratio, 0.40; 95% confidence interval, 0.19 to 0.86; P=0.02). CONCLUSIONS: Bosnian immigrants and autochthonous Croats residing in endemic areas are exposed significantly less to ingestion of aristolochic acid than in the past. The prevalence of endemic nephropathy and its associated urothelial cancers is predicted to decrease over time.

Renal function, protein excretion and pathology of Balkan endemic nephropathy. I. Renal function.

Renal function studies were performed on 59 patients who had the clinical criteria for Balkan endemic nephropathy (BEN). They were divided into three groups according to DTPA clearance (DTPA). Group 1, 11 individuals, had a mean age of 41.6 years and DTPA greater than 100 ml/min. Group 2, 20 persons, had a mean age of 49 years and DTPA of 60 to 100 ml/min. Group 3 was made up of 28 people with a DTPA less than 60 ml/min and an average age of 50.4 years. No distinguishing specific or characteristic symptoms of BEN were found in any of the three groups. Anemia was not found to be an early indicator when compared to other forms of progressive renal disease. Proteinuria was minimal and intermittent in all three groups. Maximum concentrating ability was significantly reduced only in the third group. These features do not allow the clinical differentiation of BEN from other chronic progress tubulointerstitial nephropathies. The geographic isolation and familial nature of the disease, associated with minimal proteinuria make BEN a unique entity. Kidney size by ultrasound was decreased in all three groups, suggesting that this may be another early and characteristic feature to BEN.

Renal function, protein excretion, and pathology of Balkan endemic nephropathy. II. Protein excretion.

The urinary proteins of 40 patients with Balkan endemic nephropathy from the Tuzla region were examined using ultrathin-layer SDS pore-gradient polyacrylamide gel electrophoresis in combination with silver staining. The typical urinary protein spectrum contained immunoglobulin G, Tamm-Horsfall protein, transferrin, albumin, beta 2-microglobulin (beta 2m), immunoglobulin light chains, retinol-binding protein, and alpha 1-microglobulin (alpha 1m). Densitometric measurements were used to derive glomerular tubular protein ratios (GTPR) and to characterize protein excretion patterns in the 28 patients who excreted more than 150 mg/liter of protein. Results showed that proteinuria of Balkan nephropathy is predominantly tubular, consisting of low-molecular-weight species. The most commonly identified proteins were alpha 1m, light chains, retinol binding protein, and beta 2m. The pattern of proteinuria based on GTPR did not correlate with the underlying histology or the degree of renal failure. These findings, using the ultrathin-layer SDS pore-gradient method of protein separation, more accurately demonstrates the low-molecular-weight proteinuria characteristic for the early stages of BEN.

Renal function, protein excretion, and pathology of Balkan endemic nephropathy. III. Light and electron microscopic studies.

This study was performed to evaluate histomorphological features of BEN in 50 kidney biopsies from patients who met the epidemiologic, clinical and laboratory criteria for BEN. This is the first such study reported in detail. The patients were divided into three groups based on the DTPA clearance values: group 1, greater than 99 ml/min, group 2, 51 to 99 ml/min, and group 3, 29 to 50 ml/min. All patients in all groups had an increase in proteinuria consisting of proteins less than 25,000 daltons. Multifocal interstitial sclerosis spreading from the superficial into the deep cortex was found in 49 (98%), tubular atrophy in 48 (96%), and global glomerular sclerosis with microvascular hyalinosis/sclerosis of sclerotic and atrophic changes were significantly increased when compared to age-related standards. An accelerated aging process may be assumed to occur in BEN. More peculiar additional findings with much lower incidence and extent included multifocal vascular and glomerular capillary changes resembling the chronic form of thrombotic microangiopathy group of diseases. These findings, together with the presence of arteriolar hyalinosis and tubulointerstitial sclerosis seen in patients with cyclosporine nephrotoxicity suggest that the mechanism of toxicity may be similar to BEN. We conclude that the histopathology is predominantly tubulointerstitial sclerosis without infiltrates. The combination of the histology, tubular proteinuria, geographic distribution, familial occurrence, and the remarkable association with papillary transitional cell carcinoma of the renal pelvis and ureters, qualifies BEN as a unique disease.

Renal function, protein excretion, and pathology of Balkan endemic nephropathy. IV. Immunohistology.

Few controversial observations on the deposition of immunoglobulins (Igs) and complement components in kidney biopsies of Balkan endemic nephropathy (BEN) patients have been reported. In the present study, direct or indirect immunofluorescence testing of the deposition of IgA, IgG, IgM, C3, C1q, C4 fibrin/fibrinogen, albumin, B2-microglobulin (beta 2m) and Tamm-Horsfall glycoprotein (THG) on frozen renal tissue sections was performed in 52 BEN patients. Glomerular findings were negative or mostly insignificant, with mild or moderate mesangial deposition of IgM in 16, IgA in 11, IgG in three, C3 in 15, C1q in two, C4 in one and fibrin/fibrinogen in two cases, respectively. The predominance of mesangial IgA deposits in five cases suggested IgA glomerulonephritis (GN) concomitant with BEN. Homogeneous lumpy or granular deposits in small extraglomerular vessels contained IgM in nine, C3 in 45, C1q in three, and C4 in one case. Focal linear or granular C3 was noted along the tubular basement membrane in eight cases. Resorptive droplets in tubular epithelial cells contained Igs and albumin, while complement, fibrin/fibrinogen and THG were found in tubular casts. There was no positive reaction with anti-beta 2m and anti-THG antibodies. According to these results, humoral immune mechanisms would not appear to play a pathogenetic role in BEN. However, immunohistologic examinations are important in recognition of possible concomitant immune complex-mediated GN.

Selenium-dependent and selenium-non-dependent glutathione peroxidase in patients with Balkan endemic nephropathy.

We studied the activity of erythrocyte selenium (Se)-dependent, Se-non-dependent glutathione peroxidase (GSH-Px), and superoxide dismutase (SOD) in uremic patients (UP) in clinically healthy members from families affected with Balkan nephropathy (HMF/BEN) and in healthy volunteers from endemic settlements (control group). The SOD activity was not significantly different in the groups studied and the Se-non-dependent GSH-Px activity in HMF/BEN and UP was not different from the control group. However, the activity of Se-dependent GSH-Px in UP was lower compared with the control group, whereas the mean value of the Se-dependent GSH-Px activity in HMF/BEN was not significantly different when compared with the other two investigated groups.

Clinical features of Balkan endemic nephropathy.

This paper describes the clinical symptoms and signs of Balkan endemic nephropathy (BEN). The initial asymptomatic period followed by weakness and lassitude during renal insufficiency is emphasized. Non-characteristic lumbar pain may be present and episodes of macrohaematuria may occur. There is no fever, no severe dysuria, and no general disease preceding the symptoms. No oedema of the nephrotic type is recognized. Working capacity is unaffected until the late stage of the disease. In the advanced stages pallor of the skin and xantochromia of palms and soles are noticeable. Blood pressure is normal, but in the advanced phase may be elevated. In the uraemic phase a full uraemic syndrome is found. Urothelial tumours are frequent, occurring in 2-47% of cases; tumour cells may be found in the urine. Proteinuria of tubular type may be found early; in the uraemic phase it is constant. In the urinary sediment there are scarce white and red blood cells (the latter episodically abundant). Bacteriuria is present in about 20% of women patients. Glucosuria (less than 10%) and aminoaciduria (less than 10%) have been reported. In the early stages of BEN the urine concentration capacity is impaired earlier than renal blood flow and glomerular filtration rate. Enzymuria is present in the early phases. Tamm-Horsfall protein may be increased in the urine. Normo- or hypochromic normocytic hyporegenerative anaemia is a frequent finding. Bone marrow and leucocytes are normal. Serum proteins and immunoglobulins are not altered. Complement is normal; anti-glomerular basal membrane and anti-tubular basal membrane are negative. On radiography, kidney size varies from normal to the size of a small contracted kidney. The clinical picture of the disease is that of a slowly progressing tubulo-interstitial chronic nephritis.

Some features of Balkan endemic nephropathy.

This paper presents a brief review of the initial investigative efforts in three countries--"Yugoslavia", Bulgaria and Romania--on Balkan endemic nephropathy. There is now expert agreement that the disease represents an unusual type of chronic interstitial nephropathy of unknown aetiology. The epidemiological and histopathological data are summarized very briefly. The clinical symptoms and signs and the diagnostic approach to the disease are presented in greater detail. The possibilities of an early diagnosis in the latent, subclinical and early phases of the disease are discussed, together with the importance of the detection of a tubular type of proteinuria and enzymuria as a diagnostic aid.

Balkan endemic nephropathy, the haematopoietic system and the environmental connection.

We previously reported the detection of an increased subpopulation of cytotoxic T lymphocytes in patients with Balkan (endemic) nephropathy (BEN) and in area controls (individuals free of clinical syndrome but born in a BEN endemic area and having a family history of BEN). Extending the flow-cytometric analyses to other populations of peripheral blood leucocytes, we found a decrease in the proportion of B lymphocyte subset and an increased proportion of eosinophils in BEN patients and in area controls. Although these numerical alterations cannot be categorically linked to the aetiopathogeny of the disease, it is presumed that they can be induced by the same factor(s) causing the kidney damage, through a direct haemato- and lymphotoxic effect.

Relevance of a rat model of papillary necrosis and upper urothelial carcinoma in understanding the role of ochratoxin A in Balkan endemic nephropathy and its associated carcinoma.

Ochratoxin A is nephrotoxic and has been implicated in the genesis of Balkan endemic nephropathy (BEN), a condition that leads to end-stage renal disease and upper urothelial tumours. This compound induces renal parenchymal carcinoma in male mice only, and is not considered to be a potent carcinogen nor is there experimental evidence of its propensity to cause upper urothelial carcinoma. There is, however, evidence that exposure to more than one mycotoxin may be an important factor in the clinical spectrum of BEN. Analgesic nephropathy is clinically different, but is also associated with an upper urothelial carcinoma. The combination of urothelial initiation and an acute papillary necrosis in rats produces upper urothelial carcinoma. This two-stage experimental model offers the potential to assess the role of ochratoxin A in BEN-associated upper urothelial carcinoma under experimental conditions.