Focusing on the clinical impact of standardization of creatinine measurements: a report by the EFCC Working Group on Creatinine Standardization.

The recent campaign for standardization of creatinine measurements has been promoted to allow the widespread use of formulas for estimating the glomerular filtration rate (GFR). However, studies on trueness verification and measurement interferences still show disappointing interassay variation of serum creatinine results. Creatinine recalibration has major clinical consequences. In particular, in pediatrics where reference ranges for serum and plasma creatinine are low, calculation of the GFR is problematic when based on alkaline picrate methods because of method non-specificity and the lack of appropriate GFR estimating formulas. Therefore, enzymatic creatinine assays are preferred. In the near future, cystatin C might offer an interesting alternative for GFR estimation. For the calculation of drug doses, the Modification of Diet in Renal Disease study formula generally offers reliable data. However, attention has to be paid to the elderly. Also, the calculation of the Model for End-Stage Liver Disease score, which is used to prioritize patients for liver transplantation, may significantly be influenced by recalibration of creatinine assays. Creatinine restandardization may also affect the current guidelines for referral of chronic kidney disease patients to nephrologists.

The European Register of Specialists in Clinical Chemistry and Laboratory Medicine: guide to the Register, version 3-2010.

In 1997, the European Communities Confederation of Clinical Chemistry and Laboratory Medicine (EC4) set up a Register for European Specialists in Clinical Chemistry and Laboratory Medicine. The operation of the Register is undertaken by a Register Commission (EC4RC). During the last 12 years, more than 2200 specialists in Clinical Chemistry and Laboratory Medicine have joined the Register. In 2007, EC4 merged with the Forum of European Societies of Clinical Chemistry and Laboratory Medicine (FESCC) to form the European Federation of Clinical Chemistry and Laboratory Medicine (EFCC). Two previous Guides to the Register have been published, one in 1997 and another in 2003. The third version of the Guide is presented in this article and is based on the experience gained and development of the profession since the last revision. Registration is valid for 5 years and the procedure and criteria for re-registration are presented as an Appendix at the end of the article.

IgA immune responses against acetaldehyde adducts and biomarkers of alcohol consumption in patients with IgA glomerulonephritis.

BACKGROUND: The pathogenesis of IgA glomerulonephritis (IgAGN) involves intense deposition of IgAs within the glomerulus. Although previous studies have shown that heavy drinking frequently leads to the generation of IgA antibodies against neo-antigens induced by ethanol metabolites and tissue deposition of IgAs, the associations between alcohol consumption, IgA immune responses, and kidney disease have not been examined. METHODS: A total of 158 IgAGN patients (96 men, 62 women) were classified as abstainers (n = 38), moderate drinkers (n = 114), and heavy drinkers (n = 6) based on self-reported alcohol consumption. The reference population included 143 individuals (99 men, 44 women) who were either apparently healthy abstainers (n = 31), moderate drinkers (n = 43), or heavy drinkers devoid of liver disease (n = 69). The assessments included various biomarkers of alcohol consumption: carbohydrate-deficient transferrin (CDT), glutamyl transferase, gamma-CDT (combination of GGR and CDT), mean corpuscular volume (MCV), tests for liver and kidney function, serum immunoglobulin A (IgA), and specific IgA antibodies against acetaldehyde-protein adducts. RESULTS: In male IgAGN patients, drinking status was significantly associated with MCV, p < 0.001; CDT, p < 0.01; and gamma -CDT, p < 0.05. In the reference population, all biomarkers and anti-adduct IgA levels were found to vary according to drinking status. In IgAGN patients, anti-adduct IgA levels were elevated in 63% of the cases but the titers did not associate with self-reported ethanol intake. CONCLUSIONS: These data indicate high levels of IgA antibodies against acetaldehyde-derived antigens in IgAGN patients, which may hamper the use of the immune responses as markers of alcohol consumption among such patients. Future studies on the pathogenic and prognostic significance of anti-adduct immune responses in IgAGN patients are warranted.

Alcohol consumption and kidney function in IgA glomerulonephritis.

BACKGROUND: IgA glomerulonephritis (IgAGN) is a kidney disease with variable prognosis. Several known risk factors exist for a more progressive course. Some population studies indicate that moderate alcohol consumption might protect kidney function, but the relationship between alcohol intake and IgAGN has not previously been examined. METHODS: We examined 158 (95 men) IgAGN patients (37 abstainers, 80 light drinkers, 25 moderate drinkers and 16 heavy drinkers) in a cross-sectional study. The definition of alcohol consumption was based on interviews on the amounts of alcohol intake combined with measurements of serum carbohydrate-deficient transferrin, a specific biomarker of alcohol abuse. Longitudinal data on renal function were available from 117 patients (76 men) in whom an analysis with respect to progression was also performed. RESULTS: Moderate drinkers showed the best kidney function. When adjusted by hypertension and 24-hour protein excretion, moderate alcohol consumption in a cross-sectional multivariate analysis, and both light and moderate alcohol consumption in a longitudinal multivariate analysis were significant factors of better kidney function. When the study population was divided by gender, the best kidney function was among light drinkers in women and among moderate drinkers in men. CONCLUSIONS: Moderate alcohol consumption might have a favorable impact on the progression of IgAGN. Light alcohol consumption in women and moderate consumption in men are associated with improved indices of the glomerular filtration estimates in patients with IgAGN.

The effect of parecoxib on kidney function at laparoscopic hysterectomy.

Conventional nonsteroidal anti-inflammatory drugs (NSAIDs) have a well-documented nephrotoxic action. Still, there are only few studies that have investigated the nephrotoxicity of cyclo-oxycenase-2-inhibitors during the perioperative period. Thirty patients scheduled for elective laparoscopic hysterectomy were enrolled in this prospective, randomized double-blind study. Patients were randomized into two groups: a saline-treated control group (placebo) and 80 mg parecoxib-treated group (parecoxib). The samples for the analyses of serum and urine were collected at the induction of anesthesia, two hours thereafter, two hours from the end of anesthesia, and on the first postoperative day (POD). S-crea, S-urea, S-cystatin C, S-Na, S-K, U-1mikroglobulin/U-crea, U-GST/U-crea, and U-GST/U-crea were analyzed from the samples. Urine output was measured every hour for the first five hours, and total amount of urine was measured until the first postoperative day. There were no clinical and few statistical significant differences between the two groups in the renal measurements during the study period. The urinary output was also similar in the two groups. A single dose of 80 mg of parecoxib was well tolerated by the kidneys in the short-term perioperative use in patients undergoing laparoscopic hysterectomy with ASA physiological status I-II and age under 60 years.

Inflammatory markers and the progression of IgA glomerulonephritis.

BACKGROUND: IgA glomerulonephritis (IgAGN) composes a variable prognosis with 15-40% of the patients eventually progressing to end-stage renal failure. Known risk factors for progressive course of IgAGN include hypertension, proteinuria and renal insufficiency. Although markers of inflammation such as serum or urinary interleukin-6 (IL-6) and serum albumin have predicted progression in some studies, sensitive CRP (hs-CRP) has not been directly linked to the progression of IgAGN. METHODS: A total of 174 (70 females) patients were invited for two visits 11 and 16 years (medians) after IgAGN was diagnosed in renal biopsy. All patients had been diagnosed at least 5 years before the first visit. Progressive disease was defined as cystatin-C exceeding normal limits and showing over 20% elevation between the visits, or kidney transplantation or start of dialysis. Cystatin-C and creatinine clearance, serum hs-CRP, s-albumin, s-IL-6 and white blood cell count (WBC) were available for analysis from 118 patients. RESULTS: IgAGN was progressive in 19.5% of the patients on the second visit. Hs-CRP, s-albumin and WBC of the first visit were significantly associated with the progression of IgAGN (P = 0.014; P = 0.0001; P = 0.023, respectively). S-IL-6 was not associated with the progression. All inflammatory variables correlated significantly with the concurrent level of kidney function. Possible study limitations are the relatively low number of outcomes in the study groups, and the lack of generally accepted definitions for disease progression. CONCLUSIONS: Our results suggest that inflammatory markers hs-CRP, s-albumin and WBC are associated with the progression of IgAGN.

Measurement of the kidney function in patients with rheumatoid arthritis: plasma cystatin C versus 51Cr-EDTA clearance.

BACKGROUND/AIM: Knowledge of the usefulness of cystatin C measurement in the detection of chronic kidney disease in patients with rheumatoid arthritis (RA) is scant. The purpose of this study was to evaluate the ability of plasma cystatin C- and creatinine-based methods to predict glomerular filtration rate (GFR) and classify chronic kidney disease in RA patients. METHODS: The study population consisted of 64 RA patients aged 41-86 years. Comparisons were made between measured plasma creatinine, cystatin C, creatinine clearance and GFR estimated by the Cockcroft-Gault (CG) and the Modification of Diet in Renal Disease (MDRD) formulas. The plasma clearance of (51)Cr-EDTA served as a reference. RESULTS: The Pearson correlation coefficients between plasma clearance of (51)Cr-EDTA and the markers of GFR were calculated. The correlation coefficients were 0.800 for plasma creatinine, 0.863 for cystatin C, 0.866 and 0.904 for GFR values estimated by MDRD and CG and 0.922 for plasma creatinine clearance. Statistically significant differences were detected between the correlation coefficients of plasma creatinine and GFR estimated by CG (p = 0.0412) and plasma creatinine and creatinine clearance (p = 0.0099). Creatinine clearance and the MDRD and CG formulas proved to be better at identifying GFR <90 ml/min than plasma creatinine or cystatin C. CONCLUSION: We recommend using the CG formula or creatinine clearance for the estimation of the GFR of RA patients instead of solely creatinine or cystatin C in clinical work.

Comparison of calcium phosphate product values using measurement of plasma total calcium and serum ionized calcium.

Calcium phosphate product (Ca x Pi) is a clinically relevant tool to estimate the cardiovascular risk of patients with renal failure. In reports, mostly total serum calcium has been used. As measurement of serum ionized calcium has some benefits and is being used increasingly, we estimated the respective levels of calcium phosphate product using both total (t-Ca x Pi) and ionized calcium (ion-Ca x Pi). Fifty-eight healthy individuals and 180 hemodialysis (HD) patients from 2 centers were studied. Diagnostic accuracies for corresponding values of the t-Ca x Pi and ion-Ca x Pi were calculated using a GraphROC program. Of HD patients, 64% had t-Ca x Pi <4.4 mmol(2)/L(2) regarded as a desirable goal, and 10% had values over 5.6 mmol(2)/L(2) associated with a high cardiovascular risk. Based on GraphROC analysis, t-Ca x Pi of 4.4 mmol(2)/L(2) corresponded to a value of 2.2 mmol(2)/L(2) of ion-Ca x Pi and, respectively, t-Ca x Pi of 5.6 mmol(2)/L(2) corresponded 2.8 mmol(2)/L(2) of ion-Ca x Pi. Owing to the good agreement between the results in the 2 centers, these values for risk levels can be used in both centers. When measurement of ionized calcium is used, Ca x Pi values of 2.2 and 2.8 mmol(2)/L(2) can be used instead of generally used values of 4.4 and 5.6 mmol(2)/L(2) with total calcium.

Kidney toxicity of ingested uranium from drinking water.

BACKGROUND: In experimental settings, uranium is toxic to kidneys, but effects on humans are unclear. Ingestion of water from drilled wells is a source of high uranium exposure in some populations. METHODS: Uranium exposure was measured in 95 men and 98 women aged 18 to 81 years who had used drinking water from drilled wells for an average of 16 years. Urinary N-acetyl-gamma-d-glucosaminidase, alkaline phosphatase, lactate dehydrogenase, gamma-glutamyltransferase, and glutathione-S-transferase; serum cystatin C; and urinary and serum calcium, phosphate, glucose, and creatinine were measured to evaluate possible toxic effects of uranium on kidney cells and renal function. In addition, supine blood pressure was measured. Associations between uranium exposure and the outcome variables were modeled by using linear regression with adjustment for age, sex, body mass index, smoking, and analgesic use. RESULTS: Median uranium concentration in drinking water was 25 microg/L (interquartile range, 5 to 148 microg/L; maximum, 1,500 microg/L). Indicators of cytotoxicity and kidney function did not show evidence of renal damage. No statistically significant associations with uranium in urine, water, hair, or toenails was found for 10 kidney toxicity indicators. Uranium exposure was associated with greater diastolic and systolic blood pressures, and cumulative uranium intake was associated with increased glucose excretion in urine. CONCLUSION: Continuous uranium intake from drinking water, even at relatively high exposures, was not found to have cytotoxic effects on kidneys in humans.

Weight reduction with very-low-caloric diet and endothelial function in overweight adults: role of plasma glucose.

OBJECTIVE: Obesity is associated with endothelial dysfunction that may contribute to the development of atherosclerosis. We studied whether weight reduction improves endothelial function in overweight individuals. METHODS AND RESULTS: Flow-mediated endothelium-dependent vasodilation of the brachial artery was measured in 67 adults (age: 46+/-7 years, body mass index: 35.2+/-5.4 kg/m2) before and after a 6-week weight reduction program induced by very-low-calorie diet (daily energy: 580 kcal/2.3 MJ). Caloric restriction reduced body weight from 101+/-18 to 90+/-17 kg. Flow-mediated vasodilation increased from 5.5%+/-3.7 to 8.8%+/-3.7% (P<0.0001). Nitrate-mediated vasodilation was not significantly affected. The improvement in flow-mediated dilation was associated with the reduction in plasma glucose concentration (P=0.0003). This relationship was independent of changes in weight, serum lipids, oxidized LDL, C-reactive protein, adiponectin, blood pressure, and insulin. CONCLUSIONS: Weight reduction with very-low-calorie diet improves flow-mediated vasodilation in obese individuals. This improvement is related to the reduction in plasma glucose concentration. These observations suggest that changes in glucose metabolism may determine endothelial vasodilatory function in obesity.

Elevated serum C-reactive protein levels and early arterial changes in healthy children.

OBJECTIVE: Elevated serum concentration of C-reactive protein (CRP) predicts cardiovascular events in adults. Because atherosclerosis begins in childhood, we undertook a study to determine whether changes in brachial artery endothelial function and the thickness of the carotid intima-media complex, 2 markers of early atherosclerosis, are related to CRP levels in healthy children. METHODS AND RESULTS: Brachial artery flow-mediated dilatation (FMD) and carotid artery intima-media thickness (IMT) were measured with ultrasound in 79 children (aged 10.5+/-1.1 years). Compared with the children with CRP levels under the detection limit (<0.1 mg/L, n=40, group 1), the children with higher CRP (0.1 mg/L< or =CRP< or =0.7 mg/L, n=20, group 2; CRP >0.7 mg/L, n=19, group 3) had lower FMD (9.0+/-4.4% versus 7.8+/-3.3% versus 6.5+/-2.6%, respectively; P=0.015 for trend) and greater carotid IMT (0.45+/-0.03 versus 0.46+/-0.04 versus 0.49+/-0.06 mm, respectively, P=0.002 for trend). CRP level remained a statistically significant independent predictor for brachial FMD and carotid IMT in multivariate analyses. CONCLUSIONS: These data suggest that CRP affects the arteries of healthy children by disturbing endothelial function and promoting intima-media thickening. The findings support the hypothesis that CRP plays a role in the pathogenesis of early atherosclerosis.

Metabolic syndrome in IgA glomerulonephritis.

BACKGROUND/AIMS: Metabolic syndrome (MetS) may have an independent impact on the development of chronic kidney disease. This study examines the prevalence of MetS in subjects with IgA glomerulonephritis (IgAGN) and its impact on disease progression in a retrospective fashion. PATIENTS AND METHODS: Altogether, 174 subjects (104 males) were examined 11 years (first visit) after IgAGN diagnosis and again after 16 years (second visit; 144 subjects responded). Different glomerular filtration markers were utilized. The MetS criteria by Alberti et al. [Circulation 2009;120:1640-1645] were applied, in which the presence of any three of five risk factors (elevated waist circumference, triglycerides, glucose, existence of hypertension, or reduced high-density lipoprotein cholesterol) constitutes the diagnosis. RESULTS: The prevalence of MetS at the first visit was 39%, corresponding to that of the general Finnish population. In univariate analyses, MetS was significantly associated with the progression of IgAGN at the second visit. However, in multivariate analyses, the existence of MetS was not a significant prognostic determinant. CONCLUSION: The number of subjects with MetS among IgAGN patients and the general population is equal in Finland. MetS does not seem to be an independent prognostic variable.

Cystatin C in diabetics as a marker of mild renal insufficiency after CABG.

PURPOSE: The purpose of this study was to evaluate the accuracy of plasma cystatin C in acute impairment in renal function; plasma cystatin C was compared to plasma creatinine in two hundred patients undergoing elective CABG surgery. METHODS: We performed a prospective clinical study of two hundred patients undergoing coronary bypass surgery. Plasma creatinine and cystatin C were measured preoperatively and on the first and fourth days after surgery. Estimated glomerular filtration rate (GFR) was calculated using one creatinine-based and two cystatin C-based equations. RESULTS: There were 144 non-diabetic and 56 diabetic patients. The need for furosemide was more common among diabetics (80.4% of the patients vs. 53.9%, p = 0.024). Changes in cystatin C-based GFR with both equations were significantly greater in the group of diabetics (-14.3 ± 28.0 and -11.2 ± 19.3 ml/min/1.73 m(2) vs. -4.3 ± 26.9 and -3.1 ± 20.5 ml/min/1.73 m(2), p = 0.025 and 0.016, respectively). Changes in creatinine-based GFR did not differ between the diabetics and the non-diabetics. CONCLUSION: Cystatin C and cystatin C-based estimation of GFR may be useful and more sensitive than creatinine in detecting mild acute renal insufficiency in diabetic patients.

More than half of the patients with acute Puumala hantavirus infection have abnormal cardiac findings.

This study was conducted to determine the frequency, severity and outcome of cardiac findings in patients with acute Puumala hantavirus-induced nephropathia epidemica (NE). 70 consecutive, hospital-treated patients with serologically confirmed NE were prospectively examined using serial electrocardiograms (ECG), plasma troponin I, tumour necrosis factor alpha (TNF-alpha), interleukin-6 (IL-6), and echocardiography (ECHO). Examinations were repeated after 3 and 12 months. ECG changes were observed in 57% of patients. Plasma troponin I levels remained normal in all. In six patients, ECHO showed left ventricular contraction abnormalities, and 1 patient had mild pericardial effusion. There were no differences in clinical or standard laboratory findings or in plasma TNF-alpha and IL-6 concentrations between patients with and without ECG or ECHO changes. During the follow-up, all acute-phase changes in ECG and ECHO reverted to normal, which probably reflects their benign nature. We conclude that abnormal cardiac findings are surprisingly common during NE.

The European Register of Specialists in Clinical Chemistry and Laboratory Medicine: Code of Conduct, Version 2--2008.

In 1997, the European Communities Confederation of Clinical Chemistry and Laboratory Medicine (EC4) set up a Register for European Specialists in Clinical Chemistry and Laboratory Medicine. The operation of the Register is undertaken by a Register Commission (EC4RC). During the last 10 years, more than 2000 specialists in Clinical Chemistry and Laboratory Medicine have joined the Register. In 2007, EC4 merged with the Federation of European Societies of Clinical Chemistry and Laboratory Medicine (FESCC) to form the European Federation of Clinical Chemistry and Laboratory Medicine (EFCC). A Code of Conduct was adopted in 2003 and a revised and updated version, taking account particularly of the guidelines of the Conseil Européen des Professions Libérales (CEPLIS) of which EFCC is a member, is presented in this article. The revised version was approved by the EC4 Register Commission and by the EFCC Executive Board in Paris on 6 November, 2008.

Trueness verification of actual creatinine assays in the European market demonstrates a disappointing variability that needs substantial improvement. An international study in the framework of the EC4 creatinine standardization working group.

BACKGROUND: The European In Vitro Diagnostics (IVD) directive requires traceability to reference methods and materials of analytes. It is a task of the profession to verify the trueness of results and IVD compatibility. METHODS: The results of a trueness verification study by the European Communities Confederation of Clinical Chemistry (EC4) working group on creatinine standardization are described, in which 189 European laboratories analyzed serum creatinine in a commutable serum-based material, using analytical systems from seven companies. Values were targeted using isotope dilution gas chromatography/mass spectrometry. Results were tested on their compliance to a set of three criteria: trueness, i.e., no significant bias relative to the target value, between-laboratory variation and within-laboratory variation relative to the maximum allowable error. RESULTS: For the lower and intermediate level, values differed significantly from the target value in the Jaffe and the dry chemistry methods. At the high level, dry chemistry yielded higher results. Between-laboratory coefficients of variation ranged from 4.37% to 8.74%. Total error budget was mainly consumed by the bias. Non-compensated Jaffe methods largely exceeded the total error budget. Best results were obtained for the enzymatic method. The dry chemistry method consumed a large part of its error budget due to calibration bias. CONCLUSIONS: Despite the European IVD directive and the growing needs for creatinine standardization, an unacceptable inter-laboratory variation was observed, which was mainly due to calibration differences. The calibration variation has major clinical consequences, in particular in pediatrics, where reference ranges for serum and plasma creatinine are low, and in the estimation of glomerular filtration rate.

Insulin resistance and the progression of IgA glomerulonephritis.

BACKGROUND: IgA glomerulonephritis (IgAGN) has a highly variable prognosis with 15-40% of patients progressing to end-stage renal disease. Hypertension, proteinuria and renal insufficiency are risk factors associated with poor prognosis. The role of insulin resistance is unclear in IgAGN. METHODS: From a retrospective cohort of IgAGN patients, a total of 174 patients (104 males) were invited for two visits at the clinic, 11 and 16 years (median times) after IgAGN was diagnosed in renal biopsy. Of all the patients, 63% had been diagnosed at least 10 years before the first visit. Progressive disease was defined as cystatin-C exceeding normal limits and showing over 20% elevation between the first and second visits, or kidney transplantation or start of dialysis. Plasma insulin, homeostasis model assessment of insulin resistance (HOMA-IR) index and cystatin-C were obtained for analysis from 118 patients. RESULTS: IgAGN was progressive in 19.5% of the patients on the second visit. Insulin level and HOMA-IR of the first visit showed significant association with the progression of IgAGN (P = 0.019 and 0.005, respectively). CONCLUSIONS: Our results show that in addition to the known risk factors age, hypertension, proteinuria and hyperuricaemia, plasma insulin level and calculated HOMA-IR are associated with the progression of IgAGN.

Off-pump surgery does not eliminate microalbuminuria or other markers of systemic inflammatory response to coronary artery bypass surgery.

OBJECTIVE: To evaluate whether off-pump surgery attenuates microalbuminuria and other markers of systemic inflammatory response to coronary artery bypass surgery as compared to surgery performed using cardiopulmonary bypass. DESIGN: Forty-three adult patients undergoing elective coronary artery bypass grafting surgery were operated on with or without cardiopulmonary bypass (CPB). Microalbuminuria, serum C-reactive protein, and oxygenation and lung function parameters were measured at several time points until the first postoperative morning. RESULTS: The urinary albumin/creatinine ratio was low in both groups before surgery, but reached a maximum level at the end of CPB or just after opening the last coronary artery clamp in the off-pump group (p<0.05). The urinary albumin/creatinine ratio remained slightly elevated in both groups until the morning after the operation (p<0.05). There were no statistical differences between groups. Serum C-reactive protein remained at the initial level the evening after the operation, but increased by the first postoperative morning in both groups (p<0.001). The alveolar-arterial gradient for oxygen partial pressure rose significantly after the operation in the intensive care unit in both groups (p<0.0001). The shunt fraction of the pulmonary circulation did not change in either group. CONCLUSIONS: Off-pump coronary artery surgery did not prevent the acute phase inflammatory response measured in the present study. The acute phase inflammatory response after coronary artery bypass surgery is more likely a response to the surgical trauma itself rather than to CPB.

Tubular proteinuria in pre-term and full-term infants.

Predictors of tubular proteinuria (alpha 1-M/crea ratio >10 mg/mmol) were sought in 100 infants of 24-32 weeks' (group 1) and 69 of 34-42 weeks' gestation (group 2). Random spot urine samples were obtained in the former group at the ages of 0-3 days, at 1-2 weeks and thereafter at 2-week intervals until the disappearance of tubular proteinuria, and in the latter one sample at a mean (SD) of 3.0 days' (1.3) age. In group 1, gestational age correlated negatively with the first urinary alpha 1-M/crea ratio. The highest urinary alpha 1-M/crea ratios [median (range) 39.1 mg/mmol (9.5-268.9)] occurred at a median (range) of 5 days' (1-42) age. Low gestational age and the need for inotropes predicted tubular proteinuria early after birth, whereas low gestation and long duration of ventilator treatment predicted the highest alpha 1-M/crea ratios. Prolonged vancomycin treatment and low gestational age were associated with delayed normalization of tubular proteinuria. In group 2 no significant risk factors for tubular proteinuria were found. The urinary alpha 1-M/crea ratio seems to be a sensitive indicator of renal tubular function in neonates, with low gestational age, the need for inotropes and prolonged assisted ventilation being predictors of increased tubular proteinuria. Long vancomycin courses should be avoided in pre-term infants in view of the prolonged adverse renal effects.