Changes In Serum Creatinine Concentration Research Articles

Naturally Occurring Human Urinary Peptides for Use in Diagnosis of Chronic Kidney Disease

Because of its availability, ease of collection, and correlation with physiology and pathology, urine is an attractive source for clinical proteomics/peptidomics. However, the lack of comparable data sets from large cohorts has greatly hindered the development of clinical proteomics. Here, we report the establishment of a reproducible, high resolution method for peptidome analysis of naturally occurring human urinary peptides and proteins, ranging from 800 to 17,000 Da, using samples from 3,600 individuals analyzed by capillary electrophoresis coupled to MS. All processed data were deposited in an Structured Query Language (SQL) database. This database currently contains 5,010 relevant unique urinary peptides that serve as a pool of potential classifiers for diagnosis and monitoring of various diseases. As an example, by using this source of information, we were able to define urinary peptide biomarkers for chronic kidney diseases, allowing diagnosis of these diseases with high accuracy. Application of the chronic kidney disease-specific biomarker set to an independent test cohort in the subsequent replication phase resulted in 85.5% sensitivity and 100% specificity. These results indicate the potential usefulness of capillary electrophoresis coupled to MS for clinical applications in the analysis of naturally occurring urinary peptides.

Kidney injury after contrast media: marker or mediator?

Changes in serum creatinine concentration are used to define acute kidney injury after the intravascular administration of iodinated contrast media, but less is known about the short-term increases in levels of cystatin C after angiography. A new study investigates whether cystatin C is a reliable marker of contrast-induced acute kidney injury after angiography.

EARLY AND SMALL CHANGES IN SERUM CREATININE CONCENTRATIONS ARE ASSOCIATED WITH MORTALITY IN MECHANICALLY VENTILATED PATIENTS

Emerging evidence suggests that minor changes in serum creatinine concentrations are associated with increased hospital mortality rates. However, whether serum creatinine concentration (SCr) on admission and its change are associated with an increased mortality rate in mechanically ventilated patients is not known. We have conducted an international, prospective, observational cohort study enrolling adult intensive care unit patients under mechanical ventilation (MV). Recursive partitioning was used to determine the values of SCr at the start of MV (SCr0) and the change in SCr ([DeltaSCr] defined as the maximal difference between the value at start of MV [day 0] and the value on MV day 2 at 8:00 am) that best discriminate mortality. In-hospital mortality, adjusted by a proportional hazards model, was the primary outcome variable. A total of 2,807 patients were included; median age was 59 years and median Simplified Acute Physiology Score II was 44. All-cause in-hospital mortality was 44%. The variable that best discriminated outcome was a SCr0 greater than 1.40 mg/dL (mortality, 57% vs. 36% for patients with SCr0 <or=1.40 mg/dL, P < 0.001). Among patients with SCr0 less than or equal to 1.40 mg/dL, DeltaSCr greater than 0.31 discriminated mortality (56% vs. 34%, P < 0.001). In multivariate analysis, geographic area, advanced age, severity of illness, reason for MV, and cardiovascular and hepatic failure were also associated with mortality. Our study suggests that SCr0 greater than 1.40 mg/dL and, in patients with low baseline SCr, a DeltaSCr greater than 0.31 are predictors of in-hospital mortality in mechanically ventilated patients.

Natural history and progression of atherosclerotic renal vascular stenosis

Date written: December 2008Final submission: October 2009

How Can Urine Microscopy Influence the Differential Diagnosis of AKI?

Acute kidney injury (AKI), which is associated with increased morbidity and mortality, is a relatively common complication in hospitalized patients (1–3). The most common cause of AKI in hospitalized patients is acute tubular necrosis (ATN) followed by prerenal azotemia (4). Because therapies and prognoses for prerenal azotemia and ATN differ substantially, early clinical differentiation is desirable to assist the clinician in patient treatment. For example, an early diagnosis of prerenal azotemia would facilitate early treatment to correct volume status and potentially prevent ATN. Also, in the setting of AKI from ATN, it would avoid worsening of the clinical course with incorrect therapies such as excessive volume resuscitation leading to pulmonary edema and other untoward end organ effects. Presently, the diagnosis of AKI is primarily based on changes in serum creatinine concentration, blood urea nitrogen, and urine output. These biomarkers are very helpful in diagnosis of AKI but rarely help in discriminating between ATN and prerenal azotemia. Urine biochemistry measures, such as fractional excretion of sodium and urea, also provide important information in the differentiation of AKI into traditional categories of prerenal azotemia and ATN (5–9) when the patient is not on diuretics or does not have underlying chronic kidney disease. Urinalysis and urine microscopy are also commonly used to differentiate these two causes of AKI and are generally accepted as critical for the evaluation of patients with kidney disease. Urine microscopy is the best surrogate for the histologic state of the kidney and is not affected by underlying chronic kidney disease or presence of medications. As a result, urine sediment analysis is considered an integral part of the clinical workup of kidney disease in hospitalized patients with AKI. Urinary microscopy in patients with ATN classically is described as containing renal tubular epithelial cells, renal tubular epithelial …

Early renal and vascular changes in ADPKD patients with low-grade albumin excretion and normal renal function

Autosomal dominant polycystic kidney disease (ADPKD) shows an increase in both urine monocyte chemoattractant protein-1 (MCP-1) and carotid intima-media thickness (CIMT) before changes in serum creatinine concentration. Although microalbuminuria is an index of disease progression, data on whether renal alterations and vascular remodelling are already present at normal or minimally increased levels of urine albumin excretion in early stages of the disease are lacking. Forty-eight ADPKD patients (24.8 +/- 0.8 years) with normal renal function (MDRD 108.1 +/- 3.1 ml/min) and 21 age-matched controls were studied in a cross-sectional study. The urine albumin/creatinine ratio (UACR) above the upper range of controls (6.8 mg/g) was taken as the predictor of renal alterations and vascular remodelling. Urine MCP-1, MCP-1 fractional excretion (FE(MCP-1)), endothelial-dependent vascular relaxation (EDVR), aortic pulse-wave velocity (Ao-PWV) and CIMT were chosen as biological markers. No differences between ADPKD with UACR <or=6.8 mg/g and controls were observed in urine MCP-1 (77.7 +/- 13.9 versus 57.8 +/- 6.3 ng/g), FE(MCP-1) (91 +/- 19 versus 74 +/- 8%) and CIMT (0.47 +/- 0.06 versus 0.44 +/- 0.07 mm), respectively. Conversely, ADPKD with UACR >6.8 mg/g showed values that were different from the two other groups. In addition, patients with UACR >6.8 and <20 mg/g showed greater values for urine MCP-1, FE(MCP-1) and CIMT (131.8 +/- 21.7 ng/g, 159 +/- 31% and 0.55 +/- 0.05 mm, respectively), as compared with patients with UACR <or=6.8 mg/g. The same pattern was found in a subset of normotensive ADPKD patients. No differences were found in EDVR and Ao-PWV. In young ADPKD patients, normal levels of UACR suggest that renal interstitium is comparable to that in healthy subjects and indicate an absence of subtle atherosclerotic changes in the carotid arteries. Likewise, early renal and vascular changes may be present at UACR below the levels defined as microalbuminuria.

Use of Isotonic Sodium Bicarbonate to Prevent Radiocontrast Nephropathy in Patients with Mild Pre-Existing Renal Impairment: A Meta-Analysis

Acute renal dysfunction after radiocontrast in patients with pre-existing renal impairment is not uncommon and is associated with significant morbidity and mortality. Isotonic sodium bicarbonate solution was first reported to reduce radiocontrast nephropathy in 2004. This first study was, however; limited by its small sample size and as such, the use of isotonic sodium bicarbonate to prevent radiocontrast nephropathy is still not widely used by many anaesthetists and intensivists. We meta-analysed relevant randomised controlled studies sourced from the Cochrane Controlled Trial Register (2007 issue 4), EMBASE and MEDLINE databases (1966 to April 15, 2008) without any language restriction. The use of isotonic sodium bicarbonate was associated with a significant reduction in risk of an incremental rise in serum creatinine concentration 25% above baseline (relative risk 0.22, 95% confidence interval [CI]: 0.11 to 0.44, P < 0.0001; 2 = 0%) and had a protective effect on the absolute change in serum creatinine concentration (weighted-mean-difference -9.4 micromol/l, 95% CI: -17.2 to -1.7, P = 0.02; F = 0%) and creatinine clearance (weighted-mean-difference 3.7 ml/min, 95% CI: 0.55 to 6.80, P = 0.02; F = 57.1%) after radiocontrast. The incidence of acute renal failure requiring dialysis was low (1.4%) and was not significantly different after the use of isotonic sodium bicarbonate (relative risk 0.59, 95% CI: 0.15 to 2.42, P = 0.47; F = 0%). With the limited data available, isotonic sodium bicarbonate appears to be safe and very effective in reducing radiocontrast nephropathy in patients with mild pre-existing renal impairment. A large randomised controlled study is needed to confirm whether isotonic bicarbonate can improve patient centred clinical outcomes.

Impact of minimal increases in serum creatinine on outcome in patients after cardiothoracic surgery: Do we have to revise current definitions of acute renal failure?*

Traditional cutoff values of serum creatinine considered to define postoperative acute renal failure have been challenged recently. In a previous investigation we demonstrated that minimal changes in serum creatinine concentration were associated with a substantial decrease in survival after cardiac surgery. In this investigation, we assessed the impact of minimal absolute increases in serum creatinine in a second institution, and we analyzed whether relative changes, as in the RIFLE classification and, partially, in Acute Kidney Injury Network (AKIN) classification, confer a different prognostic potential. Prospective analysis. University hospital. All consecutive patients undergoing cardiac surgery in the University Hospital of Zurich (Center USZ) over a 46-month period. Patients were prospectively documented. We analyzed maximal changes in serum creatinine in the first 48 hrs postoperatively (DeltaCrea) regarding death within 30 days. Results were compared with those of the University Hospital Vienna (Center AKH). Moreover, the prognostic potential of DeltaCrea within 48 hrs vs. serum creatinine elements according to RIFLE and AKIN classifications was assessed. A total of 3,123 patients were evaluated from USZ. The majority of patients had decreased postoperative serum creatinine values (negative DeltaCrea) and the lowest mortality (1.8%). Minimal increases, [0, 0.5) mg x dL(-1), were associated with a more than doubled mortality in both centers (5%/6%). Mortality, according to RIFLE and AKIN classifications for both populations combined, was as follows: 7,023 (3.6%), 160 (29%), 43 (19%), and 15 (33%) for RIFLE Normal, Risk, Injury, and Failure; 6,644 (2.8), 463 (16.4), 3 (66.7), and 131 (1.8) for AKIN stage 0, 1, 2, and 3. Measuring repeat serum creatinine concentrations within 48 hrs and determining DeltaCrea were the most effective discrimination method to find patients at risk for adverse postoperative outcome after cardiac surgery, better than application of this sole criterion to the RIFLE (least discriminatory) or the AKIN classification.

Conversion enzyme inhibitors in the antihypertensive treatment of patients with renal insufficiency

Changes in serum creatinine concentration and proteinuria over a period of 12 months were analysed retrospectively in hypertensives in renal failure, 39 treated with conversion-enzyme inhibitors and 41 treated with other antihypertensives. The occasionally recorded blood pressures were comparable in the two groups. Median serum creatinine levels in the patients treated with conversion-enzyme inhibitors rose from 2.33 mg/100 ml (range 1.5-5.5) after one month acutely by 0.4 mg/100 ml and then remained essentially constant. In nine patients the level was higher by greater than or equal to 0.5 mg/100 ml after 12 months than at the beginning of treatment. Proteinuria did not show any identifiable changes. On the other hand, in those patients treated with other antihypertensives, median serum creatinine concentration rose gradually over 12 months from 2.4 mg/100 ml (range 1.5-6.0) to 3.45 mg/100 ml (1.5-12.9). In 18 patients the serum creatinine level rose by less than or equal to 0.5 mg/100 ml. Five patients developed side effects to conversion-enzyme inhibitors, but none required discontinuation of treatment. It is concluded that the use of conversion-enzyme inhibitors in patients with renal failure is effective and largely safe. It apparently causes less of a rise in serum creatinine than other antihypertensives.

Percutaneous renal surgery in children with complex stones

Objective We report our experience with percutaneous nephrolithotomy (PNL) therapy for staghorn or complex pediatric renal calculi. Patients and methods We retrospectively analyzed the case records of 105 patients younger than 17 years who underwent PNL. The cases included 53 complex calculi analyzed in 51 patients. We defined complex calculi as either staghorn or those with a stone bulk larger than 300 mm 2, involving more than one calix, the upper ureter or stone in anomalous kidney. Results Mean age of patients with complex calculi was 9.7 ± 0.7 years and stone burden was 654 ± 92.4 mm 2. The median duration of PNL was 90 ± 4.7 (30–220) min. Complete clearance was achieved in 39 patients (73.6%). Of these, 32 (60.4%) required a single tract, while 21 (39.6%) required multiple tracts. With subsequent shock wave lithotripsy and PNL, the clearance rate increased to 86.8%. The average hemoglobin drop was 1.6 ± 0.16 g/dL. Assessing the factors affecting the hemoglobin drop, the number of tracts ( P = 0.01) and size of tracts ( P = 0.002) were found to be significant. The mean change in serum creatinine concentration between preoperative and postoperative measurements was −0.01 ± 0.02 mg/dL, for both patients with a single tract and those with multiple tracts. Conclusions PNL is safe and effective in the management of staghorn and complex renal calculi in children. Tract dilatation and number of tracts are important factors in reducing blood loss.

ACUTE INCREASE IN BLOOD UREA NITROGEN CAUSED BY ENTERIC NUTRITION

ACUTE INCREASE IN BLOOD UREA NITROGEN CAUSED BY ENTERIC NUTRITION

Impact of Ramadan Fasting on Renal Allograft Function

Fasting during the holy month of Ramadan is a religious duty for all healthy adult Muslims. They are only allowed to eat and drink between sunset and dawn. This study was designed to find the effect of Ramadan fasting on allograft function. We prospectively studied 19 kidney transplant recipients who voluntarily chose to fast during Ramadan versus 20 matched recipients, who had not fasted for 3 consecutive years. Data were recorded before, during, and after the fasting month. The mean posttransplant periods in the fasting and control groups were 52.6 ± 30.3 and 56.6 ± 30.0 months, respectively. A statistical analysis showed no significant changes in serum creatinine concentrations before and after Ramadan 1.07 ± 0.24 versus 1.08 ± 0.22 mg/dL ( P > .05) and 1.00 ± 0.24 versus 1.03 ± 0.28 mg/dL ( P > .05) in fasting and control groups, respectively. The results did not show any adverse effects of fasting in recipients with stable renal function. In conclusion, our study suggests that fasting during the month of Ramadan is safe and has no significant harmful effects on kidney transplant recipients with normal renal function.

Warm Ischemic Time During Laparoscopic Live Donor Nephrectomy: Effects on Graft Function

Background Laparoscopic live donor nephrectomy (LDN) has become established as a safe and effective alternative to the open procedure. However, the effect of prolonged warm ischemia time (WIT) during retrieval of the kidney remains unclear. The aim of this study was to analyze the effects of WIT on short-term and long-term graft outcomes after LDN. Method In this retrospective analysis of LDN the effects of WIT on delayed graft function, rate of decline in serum creatinine concentration (SCr) in the first 10 days, changes in SCr at 3 months, acute rejection rate changes in Δ creatinine, biopsy-proved chronic allograft rejection and graft survival were assessed according to duration of WIT. Analysis was made by comparing WIT ≤3 versus >3 minutes and WIT <5, 5–10, and >10 minutes. Results The WIT, which ranged from 1 to 15 minutes, appeared to be related to the learning curve and to technical difficulties. Prolonged WIT did not appear to have an effect on early graft function or the rate of decline in SCr during the first 3 months posttransplantation, but may be associated with an increased rate of acute rejection. Changes in Δ creatinine over time were not affected by the length of WIT during LDN. Conclusion WIT encountered during LDN has no effect on either short-term or long-term graft outcome.

Effect of N-Acetylcysteine in Prevention of Contrast-Induced Nephropathy after Coronary Angiography

Background and Objectives:Contrast-induced nephropathy (CIN) is associated with increased morbidity and mortality in coronary angiography. Although the mechanism is unclear, N-acetylcysteine (NAC) is known to protect against CIN. Preliminary studies with NAC have found conflicting results for the prevention of CIN in patients undergoing coronary angiography. This study was designed to evaluate the efficacy and safety of NAC for the prevention of CIN in patients undergoing coronary angiography. Subjects and Methods:48 patients with chronic renal insufficiency (mean (±SD) serum creatinine concentration, 2.06±0.56 mg/dL), who were undergoing coronary angiography with a nonionic, low-osmolar contrast agent, were prospectively studied. Pa- tients were randomly assigned to receive either the antioxidant, NAC (600 mg orally twice daily), and 0.45% saline intravenously (n=25), before and after administration of contrast agents, or saline only (n=23). The renal function parameters were assessed 48 hour before and after radiocontrast media administration. Results:14 of the 48 patients (29%) showed an increase in the 0.5 mg/dL serum creatinine concentration after 48 hours of contrast media administration: 4 of the 25 patients in the NAC group (16%) and 10 of the 23 in the control group (43%; p=0.036; relative risk, 0.37; 95% confidence interval, 1.04 to 7.79). In the NAC group, the mean serum creatinine concentration insignificantly increased (p=0.54), from 2.2±0.8 to 2.3±0.9 mg/dL, after 48 hours of contrast media administration; whereas, in the control group, the mean serum creatinine concentration significantly increased (p=0.011), from 1.9±0.4 to 2.2±0.8 mg/dL. The absolute change in serum creatinine concentration was significantly greater in the control than the NAC group (p=0.044). Conclusion:Prophylac- tic oral administration of the antioxidant NAC, along with hydration, prevents the decrease in the renal func- tion induced by a nonionic, low-osmolality contrast agent in patients with chronic renal insufficiency. (Korean Circulation J 2005;35:696-701)

Diagnosis of Acute Renal Failure in Very Preterm Infants

This study was designed to improve the definition of acute renal failure (ARF) in very preterm infants. Twenty-eight newborn infants with gestational age ≤32 weeks were prospectively studied in the first 5 days of life and made up a control group as they did not present risk factors for vasomotor renal insufficiency. Renal insufficiency was defined as an increase in daily serum creatinine concentration above the 99th interval limit obtained in this control group, i.e., 43 µmol/l on day 1 and/or 21 µmol/l on day 2 and/or 14 µmol/l/day on day 3 and/or 22 µmol/l/day on day 4. According to this definition, 20 very preterm infants with ARF were identified. As compared with the control group, the ARF group showed more prolonged oliguric episodes, lower diuresis, insufficient weight loss (in spite of a reduction in water intake) and also more episodes with natremia <130 mEq/l (35 vs. 0%; p < 0.05) and/or kalemia >6 mEq/l (40 vs. 11%; p < 0.05). Therefore, assessment of daily changes in serum creatinine concentration in very preterm infants allows the diagnosis of clinically significant reduction in glomerular filtration rate.

Effect of N-Acetylcysteine on Serum Creatinine Concentration in Patients with Chronic Renal Insufficiency Who Are Undergoing Coronary Angiography

Background: Prior studies have produced conflicting results on whether N-acetylcysteine (NAC) reduces the incidence of contrast-induced nephropathy (CIN) in patients undergoing coronary angiography (CA). The dosing regimens of NAC in these studies seemed impractical for everyday clinical practice. Objective:We studied the effect of NAC, with a novel dosing strategy, on serum creatinine concentration (SCr), and the incidence of CIN, in patients who were undergoing CA and/or percutaneous coronary intervention (PCI). Methods: Twenty-five subjects with baseline renal insufficiency who were undergoing CA and/or PCI were randomized to either NAC or placebo.The treatment schedule was 800 mg of NAC 12 h prior to angiography, 600 mg of NAC 2 h prior to angiography, and 600 mg of NAC 6 h after angiography or matching placebo. All subjects were hydrated with 1 ml/kg of 0.45% saline and received non-ionic contrast for angiography. The primary endpoint was change in SCr and the secondary endpoint was the incidence of CIN as defined by an increase of 0.5 mg/dl or 25% in SCr at 48 h. Results:The average SCr at enrollment was 1.7 mg/dl and average dye exposure was 171 ml. The average change in SCr in the NAC and placebo groups was 0.14 and 0.06 mg/dl, respectively (p = 0.60). The incidence of CIN was 18 and 14% in the NAC and placebo groups, respectively (p = 1.0). Conclusion: In this small study, there was no significant difference in the change inSCr nor the incidence of CIN in patients with baseline renal insufficiency undergoing CA and/or PCI who were treated with NAC or placebo.

N-Acetylcysteine in the Prevention of Radiocontrast-Induced Nephropathy: Clinical Trials and End Points

N-acetylcysteine (NAC) has been suggested to prevent radiocontrast-induced nephropathy (RCIN) in patients with a reduced renal function. However, clinical studies have not been demonstrating this effect consistently. Also, reviews and meta-analyses dealing with the question of prevention of RCIN by NAC have been controversial. Nearly all investigators used serum creatinine as surrogate end point of their trials, and changes in serum creatinine concentrations are thought to reflect the extent of renal injury as primary outcome. In a recent study, an effect of NAC on creatinine values and estimated glomerular filtration rate without any effect on cystatin C levels has been shown in volunteers with a normal renal function. Therefore, before renal protective effects of NAC in RCIN are proposed, any direct effects of NAC on creatinine, urea, and estimated glomerular filtration rate should be addressed. In future trials, the glomerular filtration rate should preferentially be measured directly, or at least additional markers of the renal function (e.g., serum cystatin C) have to be assessed. Furthermore, additional ‘hard’ end points, i.e., hospital morbidity, mortality, or dialysis dependency, should be considered in the design of future studies of RCIN.

Effect of suprarenal versus infrarenal aortic endograft fixation on renal function and renal artery patency: a comparative study with intermediate follow-up

Suprarenal fixation of aortic endografts appears to be a safe option in patients with a short or conical proximal aortic neck. However, concern persists regarding the long-term effect on renal function when renal artery ostia are crossed by the uncovered stent. We investigated the effect of suprarenal versus infrarenal endograft fixation on renal function and renal artery patency after endovascular aortic aneurysm repair. Records of 91 patients who underwent endovascular aortic aneurysm repair with a modular bifurcated stent graft between November 1999 and January 2002 were reviewed retrospectively. Two patients receiving dialysis because of chronic renal failure were excluded. Infrarenal fixation was used in 57 patients (group 1), and suprarenal fixation was used in 32 patients (group 2). In two patients in group 1 a Gianturco Z stent was inserted transrenally because of intraoperative proximal type I endoleak, and data for these patients were excluded from analysis. Follow-up evaluation was performed at 1, 6, and 12 months, and yearly thereafter, and included clinical assessment, measurement of serum creatinine concentration (SCr), and computed tomography angiography, per standard protocol. Median follow-up was 12 months (range, 1-36 months). There was no statistically significant difference in patient demographic data, aneurysm size, or preoperative risk factors. Median SCr was significantly higher in group 2 (suprarenal fixation) than in group 1 (infrarenal fixation) preoperatively (1.2 mg/dL [range, 0.6-2.3 mg/dL] vs 0.9 mg/dL [range, 0.6-1.9 mg/dL], P =.008) and at 1 month postoperatively (1.1 mg/dL [range, 0.8-5.6 mg/dL] vs 1.0 mg/dL [range, 0.6-2.1 mg/dL], P =.045). There was a significant increase in median SCr in both groups at 1 month postoperatively (group 1, 1.0 mg/dL [range, 0.6-2.1 mg/dL], P =.05; group 2, 1.1 mg/dL [range, 0.8-5.6 mg/dL] [mean SCr, 1.35 mg/dL vs 1.15 mg/dL, respectively], P <.05). In group 1 SCr was increased significantly at 6 and 12 months (P <.001), whereas in group 2 SCr also increased at 6 and 12 months, but not significantly. The change in SCr over time was not significantly different between the two groups. In two of 32 patients in group 2, renal artery occlusion developed, associated with perfusion defects in renal parenchyma and persistently elevated SCr. Analysis of renal artery patency did not demonstrate any association between patency and treatment. No patient developed hypertension during follow-up. Suprarenal endograft fixation does not lead to significant renal dysfunction, and renal artery occlusion is uncommon within 12 months. A larger study with longer follow-up is essential to determine overall effects on renal function and renal artery patency.

The effect of age on serum creatinine levels in an aging population: relevance to vascular surgery

Background and Aim. Serum creatinine is commonly used to assess and monitor renal function in the management of abdominal aortic aneurysm with endoluminal grafting, and for intervention of renal artery occlusive disease. The majority of patients selected for these procedures are elderly and serum creatinine is used post-operatively to monitor renal function. There is a need to adjust the serum creatinine concentration for age to determine the changes that might be due to the procedure: especially with endoluminal grafting using transrenal manipulation and fixation, and procedures involving interventions directly on the renal arteries. A single reference interval for serum creatinine is usually given for each sex but does not take into account variation due to age. The objective of this study was to establish age related reference intervals for serum creatinine, especially for those over 60 years of age to assist in the clinical interpretation of creatinine levels in the years following endoluminal grafting for aneurysms of the abdominal aorta. Methods. A pathology services database was established for serum creatinine measurements from 98,688 patients (44,784 males and 53,904 females). Data was stratified into five year age groups and reference intervals assigned for each age group after a reference population was determined. The heterogeneous population was refined firstly by removing patients with extreme (≥200 μmol/l) concentrations of serum creatinine, outliers and repeated values. Secondly, a putative “healthy” population was determined by removing values outside three standard deviations of the mean. Two statistical methods, the Bhattacharya and Hoffmann methods, were then applied to obtain a putative reference population. Serum creatinine data was obtained from the Busselton Population Research Foundation for comparison. Findings. Serum creatinine concentration increased steadily with age; in females from the age of 40 years and 60 years for males. Reference intervals for males and females aged from 20 to 94 years were established. Advancing age affects serum creatinine levels, especially in the “vascular” age group of 60 to 80 years. The changes in serum creatinine concentration that occur with age is relevant in interpretation of the results of renal monitoring after intervention.

The Effect of Age on Serum Creatinine Levels in an Aging Population: Relevance to Vascular Surgery

Background and Aim. Serum creatinine is commonly used to assess and monitor renal function in the management of abdominal aortic aneurysm with endoluminal grafting, and for intervention of renal artery occlusive disease. The majority of patients selected for these procedures are elderly and serum creatinine is used post-operatively to monitor renal function. There is a need to adjust the serum creatinine concentration for age to determine the changes that might be due to the procedure: especially with endoluminal grafting using transrenal manipulation and fixation, and procedures involving interventions directly on the renal arteries. A single reference interval for serum creatinine is usually given for each sex but does not take into account variation due to age. The objective of this study was to establish age related reference intervals for serum creatinine, especially for those over 60 years of age to assist in the clinical interpretation of creatinine levels in the years following endoluminal grafting for aneurysms of the abdominal aorta. Methods. A pathology services database was established for serum creatinine measurements from 98,688 patients (44,784 males and 53,904 females). Data was stratified into five year age groups and reference intervals assigned for each age group after a reference population was determined. The heterogeneous population was refined firstly by removing patients with extreme (≥200 μmol/1) concentrations of serum creatinine, outliers and repeated values. Secondly, a putative “healthy” population was determined by removing values outside three standard deviations of the mean. Two statistical methods, the Bhattacharya and Hoffmann methods, were then applied to obtain a putative reference population. Serum creatinine data was obtained from the Busselton Population Research Foundation for comparison. Findings. Serum creatinine concentration increased steadily with age; in females from the age of 40 years and 60 years for males. Reference intervals for males and females aged from 20 to 94 years were established. Advancing age affects serum creatinine levels, especially in the “vascular” age group of 60 to 80 years. The changes in serum creatinine concentration that occur with age is relevant in interpretation of the results of renal monitoring after intervention.