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.

Evaluation of diagnostic criteria for endemic nephropathy.

Diagnosis of endemic nephropathy (EN) is based on the combination of several clinical and laboratory criteria. Despite extensive research no specific diagnostic biomarker for EN has yet been identified. The aim of the study was to evaluate the diagnostic significance of the variables previously proposed as diagnostic criteria, but also new ones. After an extended questionnaire, the clinical and laboratory examination population in EN villages was classified according to the modified WHO criteria. The urinary active form of TGF-ß was measured with a bioassay using a cell line which expresses luciferase activity. In the study we used ROC analysis to examine the predictive value of the tested variables. In the study there was no difference in haemoglobin level between the study subgroups. Leucine aminopeptidase (LAP) in urine and active urinary TGF-ß levels were increased in the EN diseased group when compared to other subgroups, but they did not fulfil the statistical criteria needed for differentiating a diseased form from other study subgroups. Both kidney length and parenchima thickness, alfa1-microglobulinuria, and kidney function assessed by MDRD formula were the variables that differentiated the study subgroups well. Based on our results the cut-off value of alfa1-microglobulin for screening should be 23.5 mg/g creatinine instead of 15 mg/g creatinine in the present criteria, and for making a diagnosis of EN 31,5 mg/g creatinine. Persons with a positive family history for EN had a 5.8 times greater risk of developing EN when compared to a negative one. Taken together, the above-mentioned variables should be implemented in new uniform diagnostic criteria for EN.

The risk of developing endemic nephropathy in subjects with proteinuria.

Endemic nephropathy is a chronic tubulointerstitial disease characterized by early damage to the proximal tubule, with low-molecular weight proteinuria being an important hallmark and possible tool for early diagnosis. The aim of this retrospective cohort study was to assess the risk of developing endemic nephropathy in subjects with proteinuria from the endemic region in Croatia. The cohort study included subjects with proteinuria determined by the sulfosalicylic acid method (after 1988 with strip method), involved in the field survey conducted in the Croatian endemic village of Kaniza in 1975 and followed up until 1997. Subjects with endemic nephropathy established at the first visit and patients that failed to present for follow up visits after 1975. were excluded. In the field survey group that consisted of 624 subjects (286 male and 338 female), proteinuria was established in 157 subjects. Upon the application of exclusion and inclusion criteria, the study cohort included 111 of 157 subjects. The mean follow up was 7.26 years (95% confidence interval 4.06-10.46 years). During the follow up period, 19 (17%) subjects with initial proteinuria developed endemic nephropathy. The incidence density of endemic nephropathy among subjects with proteinuria was 1.3 per 100 persons/year. Estimated risk was 0.0137 (confidence interval 0.0087-0.0214) per year of exposure. The presence of proteinuria determined by the sulfosalicylic acid or test strip in subjects from the endemic village indicated that endemic nephropathy would develop in 1.3 of 100 subjects with proteinuria per year.

Consensus statement on screening, diagnosis, classification and treatment of endemic (Balkan) nephropathy.

Currently used diagnostic criteria in different endemic (Balkan) nephropathy (EN) centers involve different combinations of parameters, various cut-off values and many of them are not in agreement with proposed international guidelines. Leaders of EN centers began to address these problems at scientific meetings, and this paper is the outgrowth of those discussions. The main aim is to provide recommendations for clinical work on current knowledge and expertise. This document is developed for use by general physicians, nephrologists, urologist, public health experts and epidemiologist, and it is hoped that it will be adopted by responsible institutions in countries harboring EN. National medical providers should cover costs of screening and diagnostic procedures and treatment of EN patients with or without upper urothelial cancers.

Could disappearance of endemic (Balkan) nephropathy be expected in forthcoming decades?

BACKGROUND/AIMS: An epidemiological survey of endemic nephropathy (EN) was performed in endemic Croatian areas and the current prevalence was compared to that reported for the same villages several decades ago. METHODS: A total of 2,487 adult farmers from 6 endemic villages and 3 non-endemic villages were enrolled. An extensive epidemiological questionnaire, clinical examination and laboratory analyses of blood and urine were performed. According to the modified WHO criteria, participants were classified into diseased, suspected of having EN, and those at risk of developing EN. RESULTS: The overall prevalence of EN in the Croatian areas was 1.0%, ranging between 0.3 and 2.3% in different villages. Those suspected of having EN amounted to 3.9%. In the endemic villages a decreasing trend in the prevalence of EN was observed comparable to the results obtained in previous surveys. It is interesting to note that no EN patients were recorded in the endemic village of Dubocac. CONCLUSION: The prevalence of EN in the endemic Croatian areas appears to be decreasing. For the first time, we failed to detect any EN patients in a village that was previously considered endemic, which might indicate that EN is diminishing.

Clinical chemistry and laboratory medicine in Croatia: regulation of the profession.

Heterogeneity exists across Europe in the definition of the profession of clinical chemistry and laboratory medicine and also in academic background of specialists in this discipline. This article provides an overview of the standards of education and training of laboratory professionals and quality regulations in Croatia. Clinical chemistry in Croatia is almost exclusively practiced by medical biochemists. Although term Medical biochemist often relates to medical doctors in other European countries, in Croatia medical biochemists are not medical doctors, but university degree professionals who are qualified scientifically. Practicing the medical biochemistry is regulated by The Health Care Law, The Law of the Medical Biochemistry Profession and The Law of the State and Private Health Insurance. According to the law, only medical biochemists are entitled to run and work in the medical biochemistry laboratory. University degree is earned after the 5 years of the studies. Register for medical biochemists is kept by the Croatian Chamber of Medical Biochemists. Licensing is mandatory, valid for 6 years and regulated by the government (Law on the Health Care, 1993). Vocational training for medical biochemists lasts 44 months and is regulated by the national regulatory document issued by the Ministry of Health. Accreditation is not mandatory and is provided by an independent, non-commercial national accreditation body. The profession has interdisciplinary character and a level of required competence and skills comparable to other European countries.

[Performance Assessment Tool for Quality Improvement in Hospitals (PATH): first experiences in Croatia]. / Alat za ocjenu rada u cilju poboljsanja kvalitete u bolnicama: prva iskustva u provodenju programa PATH u hrvatskim bolnicama.

PATH (Performance Assessment Tool for Quality Improvement in Hospitals), a project of the World Health Organization (WHO) for Europe offers hospitals a comprehensive and standardized tool (a set of indicators) to evaluate their own performance and development of measures for quality improvement. PATH Program was launched in Croatia in 2008, and it was conducted in 2009 in hospitals that have voluntarily decided to be involved. Here we present the results of the first phase of pilot experience of establishing the program, based on data collected in 22 Croatian hospitals. Analysis of the first results indicated the existence of marked differences among the hospitals that have taken the example of the percentage of cesarean sections ranging from 1.1% to 21.4%. The mortality rate of myocardial infarction ranged from 1.9 to 21.4%, while the mortality of stroke ranged from 12.5 to 45.5%. The highest percentage of needle-stick injuries reported for physicians was 16.2% of entire hospital staff in one year, 6.1% for nurses and 4.6% for the supportive staff. The result suggests the existence of many problems and limitations in data collection at hospital level, limitations in their analysis and creates recommendations for quality improvements, which must be taken into account when hospitals are compared on the national or international level.

Angiotensin-converting enzyme gene polymorphism and N-Acetyl-ß-D-glucosaminidase excretion in endemic nephropathy.

BACKGROUND: Tubular proteinuria and enzymuria are hallmarks of endemic nephropathy (EN). The role of I/D angiotensin convertase (ACE) gene polymorphism has not yet been elucidated in this peculiar chronic tubulointerstitial nephritis, and our aim was to investigate the role of this polymorphism in EN focusing on the urinary N-acetyl-ß-D-glucosaminidase (NAG) excretion, a biomarker of proximal tubular damage. METHODS: ACE genotype and allele frequencies were determined in 229 farmers (147 women and 82 men) from an endemic Croatian village. The farmers were stratified according to the WHO criteria into the following subgroups: those 'at risk' for EN (n = 37), 'suspected of having EN' (n = 57), and 'others' (n = 135). RESULTS: There were 74 (32.3%) subjects homozygous for the D allele, 99 (43.2%) heterozygous (ID genotype) and 56 (24.4%) homozygous for the I allele. No differences in allele frequency were found between the established WHO subgroups (p > 0.05). In the whole group, DD subjects had significantly higher values of diastolic blood pressure (p = 0.003) and urinary NAG than subjects with ID and II genotype (5.5 ± 1.2 vs. 4.0 ± 3.0 vs. 3.8 ± 4.2, respectively; p = 0.023). The highest values of serum creatinine (p = 0.02), proteinuria (p = 0.03) and urinary NAG (6.0 ± 3.7 vs. 3.7 ± 2.1 vs. 3.0 ± 1.6, respectively; p = 0.008) were observed in those suspected of having EN group with the DD genotype. CONCLUSION: ACE gene polymorphism is not a risk factor for EN. However, it might influence the clinical course of EN, and increased excretion of NAG might be a prognostic marker of this chronic tubulointerstitial nephritis.

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.

[Cardiac natriuretic peptides in heart failure]. / Srcani natriureticki peptidi u zatajivanju srca.

Heart failure is a clinical syndrome characterized by abnormalities of cardiac, skeletal muscle, and renal function, stimulation of the sympathetic nervous system, and a complex pattern of neurohormonal changes. Early diagnosis and treatment of heart failure are important factors in reducing morbidity and mortality associated with the disease. During the past several years many studies have demonstrated that natriuretic peptides are the biochemical markers of choice for diagnosing and risk stratification of patients with chronic heart failure. The value of natriuretic peptides has already been recognized by their inclusion in the recent European guidelines for the diagnosis of chronic heart failure. The natriuretic peptides family is comprised of four peptides, each with common 17 amino acid ring structure. The tissue-specific distribution and regulation of each peptide are different. At present, there is no consensus on the most reliable method for natriuretic peptides assay, although non-competitive immunoassay may be more suitable for clinical routine than competitive assay.

[The estimation of glomerular filtration rate using prediction equations]. / Procjena glomerularne filtracije s pomocu prediktivnih jednadzbi.

In clinical practice, serum creatinine is most commonly used to estimate glomerular filtration rate (GF) although it is well known that serum creatinine may be influenced by GF and factors independent of GF (age, sex, race, body size, diet, certain drugs and analytical methods). Creatinine clearance is a more sensitive marker of GF, but it overestimates GF because of tubular secretion of creatinine, and it often involves errors in 24-hour urine collection. According to the NKF/KDOQI (National Kidney Foundation Kidney Disease Outcome Quality Initiative) guidelines, the level of GF should be estimated from prediction equations taking into accout serum creatinine concentration and demographic characteristics. The aim of this work is to emphasize the clinical usefulness of these equations in estimating GF. Using prediction equations to estimate GF does not require timed urine collection susceptible to errors which are the most common underlying cause of unreliable estimation of GF done by creatinine clearance.

[Harmonization of laboratory medicine in Croatia]. / Harmonizacija laboratorijske medicine u Hrvatskoj.

In order to harmonize laboratory results in the field of general medical biochemistry at the national level, analytical methods and analytical quality goals based on biological criteria together with common reference intervals were recommended. The following parameters are included: general biochemical parameters (metabolites and substrates, enzymes, electrolytes, microelements, proteins, lipids), routine urine and stool analysis and laboratory haematology and coagulation. The main purpose of external quality control in medical biochemical laboratories is to ensure independent and objective evaluation of laboratory test results in order to promote harmonization and achieve a high degree of interlaboratory comparability. The recommended reference intervals were produced on a representative sample group of urban population in Croatia for school children, adolescents and adults. For pediatric population, reference intervals were recommended according to the literature data. The recommended laboratory methods and corresponding reference intervals in the field of general medical biochemistry have to be used in all medical biochemical laboratories in Croatia since January 1, 2005.

[Development of laboratory information system--quality standards]. / Razvoj laboratorijskog informacijskog sustava--norme kvalitete.

The aim of the study was to determine structural modules of laboratory information system (LIS) for the application of new biomedical and information technologies by utilizing current organizational trends. The method used included definition of structural modules according to significant LIS properties, e.g., a large number of data, automation of analyses and rapid exchange of information, and according to the process of information establishment the collection, organization, selection, synthesis and distribution. Thus, outdated distributed software at the Clinical Institute of Laboratory Diagnosis has now been replaced by modular organization. Modules have been developed for the following: data input, online operation of laboratory instruments, preparation of results, compilation of medical documentation on quality assurance based on the application of quality standards, management of finances, and for point of care testing. The method of re-engineering as well as adherence to EN and ISO quality standards were utilized in planning the development of LIS based on the application of new information technologies and in shaping business processes. The application of re-engineering in LIS development results in quality improvement, reduces the cost and time necessary for performance of procedures, and improves relations in organizational structure.

Biochemical changes in the sublingual and submandibular glands after interruption of chorda tympani.

The left chorda tympani nerve was interrupted through meatus acusticus externus in ten dogs. In total, 40 dog salivary glands (20 submandibular and 20 sublingual) innervated via chorda tympani were examined. Twenty glands (10 submandibular and 10 sublingual) on the left side were deprived of parasympathetic innervation by chordectomy, whereas contraleteral glands, on the right side, served as controls. Biochemical analysis showed that the interruption of chorda tympani did not cause any significant changes in the concentrations of eight enzymes investigated, i.e. lactate dehydrogenase, alkaline phosphatase, acid phosphatase, amylase, aspartate aminotransferase, alanine aminotransferase, gamma-glutamyltransferase and creatine kinase. There were no significant changes in the concentrations of most important extracellular ions (sodium, potassium, chloride and phosphorus) in the right glands, but the loss of parasympathetic innervation in the left glands was found to cause a statistically significant decrease in the concentration of potassium as intracellular cation and of phosphorus as extracellular anion.

[Rational utilization of laboratory diagnosis]. / Racionalna laboratorijska dijagnostika.

Standard way of laboratory utilisation does not meet professional and financial criteria. Rational laboratory use, which in essence means nothing else than seeking the answer to a specific clinical question, must be the basis for a changing approach towards laboratory diagnostics. In order to do that, clinicians need to have access to all the information necessary for right data interpretation, which is usually not the case. The following points are discussed: clinicians have to get acquainted with the preanalytical issues which affect the laboratory result, with analytical and biological variability of any given laboratory parameter, critical difference within longitudinal patient evaluation, as well as with diagnostic specificity and sensitivity which determine the value of a test within certain clinical context. Preanalytical phase comprises all the influences affecting the patient and the specimen and it can have a substantial impact on laboratory values. Biological variability is mainly dependent on homeostatic regulation, and it might thus be considerably high for certain parameters (end products of the metabolism, enzymes). As a consequence, the value of critical difference (absolute value in actual units which reflects a true change in clinical status) might be unexpectedly high. Finally, diagnostic sensitivity and specificity are main determinants of diagnostic performance of any given test and the lack of this information is a frequent cause of inappropriate laboratory use.