The incidence and outcome of AKI in patients with sepsis in the emergency department applying different definitions of AKI and sepsis

BACKGROUND

Sepsis is often accompanied with acute kidney injury (AKI). The incidence of AKI in patients visiting the emergency department (ED) with sepsis according to the new SOFA criteria is not exactly known, because the definition of sepsis has changed and many definitions of AKI exist. Given the important consequences of early recognition of AKI in sepsis, our aim was to assess the epidemiology of sepsis-associated AKI using different AKI definitions (RIFLE, AKIN, AKIB, delta check, and KDIGO) for the different sepsis classifications (SIRS, qSOFA, and SOFA).

METHODS

We retrospectively enrolled patients with sepsis in the ED in three hospitals and applied different AKI definitions to determine the incidence of sepsis-associated AKI. In addition, the association between the different AKI definitions and persistent kidney injury, hospital length of stay, and 30-day mortality were evaluated.

RESULTS

In total, 2065 patients were included. The incidence of AKI was 17.7-51.1%, depending on sepsis and AKI definition. The highest incidence of AKI was found in qSOFA patients when the AKIN and KDIGO definitions were applied (51.1%). Applying the AKIN and KDIGO definitions in patients with sepsis according to the SOFA criteria, AKI was present in 37.3% of patients, and using the SIRS criteria, AKI was present in 25.4% of patients. Crude 30-day mortality, prolonged length of stay, and persistent kidney injury were comparable for patients diagnosed with AKI, regardless of the definition used.

CONCLUSION

The incidence of AKI in patients with sepsis is highly dependent on how patients with sepsis are categorised and how AKI is defined. When AKI (any definition) was already present at the ED, 30-day mortality was high (22.2%). The diagnosis of AKI in sepsis can be considered as a sign of severe disease and helps to identify patients at high risk of adverse outcome at an early stage.

[A man with bulging eyes]

Graves' orbitopathy may cause multiple symptoms, such as proptosis, redness or inflammation of the conjunctiva, excessive tearing, swelling of the eyelids and pain. Smoking, male gender and old age are significant risk factors for a more severe and active disease.

Progressive kidney failure in chronic myelomonocytic leukaemia: don't forget lysozyme damage

Kidney failure is common in haematologic malignancies. However, the nephrotoxic effect of lysozyme is seldom recognized. We present a 78-year-old male with chronic myelomonocytic leukaemia who developed progressive kidney failure due to increased production of lysozyme.

[Hypernatremia caused by treatment with GHB obtained via a doctor's prescription]

In the last few years, gamma hydroxybutyric acid (GHB) has been used increasingly as a party drug; this has led to a marked increase in the number of requests for professional help with the treatment of GHB addiction. Pharmaceutical GHB (sodium oxybate, the sodium-salt of GHB), registered for cataplexia in narcolepsy patients, is used off-label to treat the withdrawal symptoms associated with GHB addiction. Pharmaceutical GHB has a high sodium load. In this report we present the cases of two patients who developed symptomatic hypernatremia following treatment with pharmaceutical GHB and who thereafter needed intensive care for the severe withdrawal symptoms that they experienced.

A Multicenter Study of the Predictive Value of Crescents in IgA Nephropathy

The Oxford Classification of IgA nephropathy does not account for glomerular crescents. However, studies that reported no independent predictive role of crescents on renal outcomes excluded individuals with severe renal insufficiency. In a large IgA nephropathy cohort pooled from four retrospective studies, we addressed crescents as a predictor of renal outcomes and determined whether the fraction of crescent-containing glomeruli associates with survival from either a ≥50% decline in eGFR or ESRD (combined event) adjusting for covariates used in the original Oxford study. The 3096 subjects studied had an initial mean±SD eGFR of 78±29 ml/min per 1.73 m² and median (interquartile range) proteinuria of 1.2 (0.7-2.3) g/d, and 36% of subjects had cellular or fibrocellular crescents. Overall, crescents predicted a higher risk of a combined event, although this remained significant only in patients not receiving immunosuppression. Having crescents in at least one sixth or one fourth of glomeruli associated with a hazard ratio (95% confidence interval) for a combined event of 1.63 (1.10 to 2.43) or 2.29 (1.35 to 3.91), respectively, in all individuals. Furthermore, having crescents in at least one fourth of glomeruli independently associated with a combined event in patients receiving and not receiving immunosuppression. We propose adding the following crescent scores to the Oxford Classification: C0 (no crescents); C1 (crescents in less than one fourth of glomeruli), identifying patients at increased risk of poor outcome without immunosuppression; and C2 (crescents in one fourth or more of glomeruli), identifying patients at even greater risk of progression, even with immunosuppression.

Tonsillectomy in a European Cohort of 1,147 Patients with IgA Nephropathy

BACKGROUND

Tonsillectomy has been considered a treatment for IgA nephropathy (IgAN). It is aimed at removing a source of pathogens, reducing mucosa-associated lymphoid tissue and decreasing polymeric IgA synthesis. However, its beneficial effect is still controversial. In Asia, favorable outcomes have been claimed mostly in association with corticosteroids. In Europe, small, single-center uncontrolled studies have failed to show benefits.

METHODS

The European validation study of the Oxford classification of IgAN (VALIGA) collected data from 1,147 patients with IgAN over a follow-up of 4.7 years. We investigated the outcome of progression to end-stage renal disease (ESRD) and/or 50% loss of estimated glomerular filtration rate (eGFR) and the annual loss of eGFR in 61 patients who had had tonsillectomy.

RESULTS

Using the propensity score, which is a logistic regression model, we paired 41 patients with tonsillectomy and 41 without tonsillectomy with similar risk of progression (gender, age, race, mean blood pressure, proteinuria, eGFR at renal biopsy, previous treatments and Oxford MEST scores). No significant difference was found in the outcome. Moreover, we performed an additional propensity score pairing 17 patients who underwent tonsillectomy after the diagnosis of IgAN and 51 without tonsillectomy with similar risk of progression at renal biopsy and subsequent treatments. No significant difference was found in changes in proteinuria, or in the renal end point of 50% reduction in GFR and/or ESRD, or in the annual loss of eGFR.

CONCLUSION

In the large VALIGA cohort of European subjects with IgAN, no significant correlation was found between tonsillectomy and renal function decline.

Hepatocyte Nuclear Factor 1β-Associated Kidney Disease: More than Renal Cysts and Diabetes

Hepatocyte nuclear factor 1β (HNF1β)-associated disease is a recently recognized clinical entity with a variable multisystem phenotype. Early reports described an association between HNF1B mutations and maturity-onset diabetes of the young. These patients often presented with renal cysts and renal function decline that preceded the diabetes, hence it was initially referred to as renal cysts and diabetes syndrome. However, it is now evident that many more symptoms occur, and diabetes and renal cysts are not always present. The multisystem phenotype is probably attributable to functional promiscuity of the HNF1β transcription factor, involved in the development of the kidney, urogenital tract, pancreas, liver, brain, and parathyroid gland. Nephrologists might diagnose HNF1β-associated kidney disease in patients referred with a suspected diagnosis of autosomal dominant polycystic kidney disease, medullary cystic kidney disease, diabetic nephropathy, or CKD of unknown cause. Associated renal or extrarenal symptoms should alert the nephrologist to HNF1β-associated kidney disease. A considerable proportion of these patients display hypomagnesemia, which sometimes mimics Gitelman syndrome. Other signs include early onset diabetes, gout and hyperparathyroidism, elevated liver enzymes, and congenital anomalies of the urogenital tract. Because many cases of this disease are probably undiagnosed, this review emphasizes the clinical manifestations of HNF1β-associated disease for the nephrologist.

Corticosteroids in IgA Nephropathy: A Retrospective Analysis from the VALIGA Study

Current guidelines suggest treatment with corticosteroids (CS) in IgA nephropathy (IgAN) when proteinuria is persistently ≥1 g/d despite 3-6 months of supportive care and when eGFR is >50 ml/min per 1.73 m(2). Whether the benefits of this treatment extend to patients with an eGFR≤50 ml/min per 1.73 m(2), other levels of proteinuria, or different renal pathologic lesions remains unknown. We retrospectively studied 1147 patients with IgAN from the European Validation Study of the Oxford Classification of IgAN (VALIGA) cohort classified according to the Oxford-MEST classification and medication used, with details of duration but not dosing. Overall, 46% of patients received immunosuppression, of which 98% received CS. Treated individuals presented with greater clinical and pathologic risk factors of progression. They also received more antihypertensive medication, and a greater proportion received renin angiotensin system blockade (RASB) compared with individuals without immunosuppressive therapy. Immunosuppression was associated with a significant reduction in proteinuria, a slower rate of renal function decline, and greater renal survival. Using a propensity score, we matched 184 subjects who received CS and RASB to 184 patients with a similar risk profile of progression who received only RASB. Within this group, CS reduced proteinuria and the rate of renal function decline and increased renal survival. These benefits extended to those with an eGFR≤50 ml/min per 1.73 m(2), and the benefits increased proportionally with the level of proteinuria. Thus, CS reduced the risk of progression regardless of initial eGFR and in direct proportion to the extent of proteinuria in this cohort.

Corticosteroids in IgA Nephropathy: A Retrospective Analysis from the VALIGA Study

Current guidelines suggest treatment with corticosteroids (CS) in IgA nephropathy (IgAN) when proteinuria is persistently ≥1 g/d despite 3-6 months of supportive care and when eGFR is >50 ml/min per 1.73 m(2). Whether the benefits of this treatment extend to patients with an eGFR≤50 ml/min per 1.73 m(2), other levels of proteinuria, or different renal pathologic lesions remains unknown. We retrospectively studied 1147 patients with IgAN from the European Validation Study of the Oxford Classification of IgAN (VALIGA) cohort classified according to the Oxford-MEST classification and medication used, with details of duration but not dosing. Overall, 46% of patients received immunosuppression, of which 98% received CS. Treated individuals presented with greater clinical and pathologic risk factors of progression. They also received more antihypertensive medication, and a greater proportion received renin angiotensin system blockade (RASB) compared with individuals without immunosuppressive therapy. Immunosuppression was associated with a significant reduction in proteinuria, a slower rate of renal function decline, and greater renal survival. Using a propensity score, we matched 184 subjects who received CS and RASB to 184 patients with a similar risk profile of progression who received only RASB. Within this group, CS reduced proteinuria and the rate of renal function decline and increased renal survival. These benefits extended to those with an eGFR≤50 ml/min per 1.73 m(2), and the benefits increased proportionally with the level of proteinuria. Thus, CS reduced the risk of progression regardless of initial eGFR and in direct proportion to the extent of proteinuria in this cohort.

[Cryptococcal meningitis]

Immunocompromised patients are at increased risk of disseminated cryptococcal infection, often presenting as a primary respiratory infection with yeast cells originating from bird excreta. Because Cryptococcus neoformans has a tropism for cerebrospinal fluid, most patients suffer from meningitis or meningoencephalitis. Symptoms of cryptococcal meningitis are non-specific: headache, fever, nausea, or altered mental state and behaviour. Case descriptions of a renal transplant recipient and an HIV patient illustrate the non-specific presentation of cryptococcal meningitis. Lumbar puncture seemed to be critical in establishing the diagnosis. Cerebrospinal fluid, blood and other tissues were tested for C. neoformans by microscopy, culture and antigen tests. The patients were successfully treated with amphotericin B or liposomal amphotericin B intravenously and flucytosine intravenously or orally, followed by long-term fluconazole. The mortality rate for cryptococcal meningitis is 41% among renal transplant recipients and 20% in HIV patients.

Novel aspects of atypical haemolytic uraemic syndrome and the role of eculizumab

The haemolytic uraemic syndrome (HUS) is part of a spectrum of thrombotic microangiopathies. The most common etiologies of HUS are the ones seen in childhood caused by an infection of Shiga toxin-producing Escherichia coli, HUS caused by an infection with Streptococcus pneumoniae and HUS due to abnormalities in the alternative pathway of the complement system. In the past decade, enormous progress has been made in understanding the pathogenesis in the latter group of patients. The analysis of genes that encode for complement regulatory proteins and the development of assays for measuring the activity of ADAMTS13 and the detection of antibodies against factor H contributed significantly to the diagnostic tools in patients with HUS. These assays have made it possible to clearly differentiate between thrombotic thrombocytopenic purpura and various forms of HUS. With the introduction of eculizumab, a monoclonal anti-C5 inhibitor, in the clinical arena as effective treatment of most complement-mediated forms of HUS, a new era of treatment in HUS has begun. We review the recent advances in HUS, with the focus on treatment. We discuss unsolved questions, which should be addressed in future studies.

Prevalence, awareness, and management of CKD and cardiovascular risk factors in publicly funded health care

BACKGROUND AND OBJECTIVES

It is uncertain how many patients with CKD and cardiovascular risk factors in publicly funded universal health care systems are aware of their disease and how to achieve their treatment targets.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

The CARTaGENE study evaluated BP, lipid, and diabetes profiles as well as corresponding treatments in 20,004 random individuals between 40 and 69 years of age. Participants had free access to health care and were recruited from four regions within the province of Quebec, Canada in 2009 and 2010.

RESULTS

CKD (Chronic Kidney Disease Epidemiology Collaboration equation; <60 ml/min per 1.73 m(2)) was present in 4.0% of the respondents, and hypertension, diabetes, and hypercholesterolemia were reported by 25%, 7.4%, and 28% of participants, respectively. Self-awareness was low: 8% for CKD, 73% for diabetes, and 45% for hypercholesterolemia. Overall, 31% of patients with hypertension did not meet BP goals, and many received fewer antihypertensive drugs than appropriately controlled individuals; 41% of patients with diabetes failed to meet treatment targets. Among those patients with a moderate or high Framingham risk score, 53% of patients had LDL levels above the recommended levels, and many patients were not receiving a statin. Physician checkups were not associated with greater awareness but did increase the achievement of targets.

CONCLUSION

In this population with access to publicly funded health care, CKD and cardiovascular risk factors are common, and self-awareness of these conditions is low. Recommended targets were frequently not achieved, and treatments were less intensive in those patients who failed to reach goals. New strategies to enhance public awareness and reach guideline targets should be developed.

Living kidney transplantation in adult patients with atypical haemolytic uraemic syndrome

BACKGROUND

Dysregulation of complement activation is the most common cause of the atypical haemolytic uraemic syndrome (aHUS). Many patients with aHUS develop end-stage renal disease and consider kidney transplantation. However, the recurrence rate after transplantation ranges from 45-90% in patients with known abnormalities in circulating complement proteins. It was recently proposed that patients with aHUS should be treated prophylactically with plasma exchange or eculizumab to prevent recurrence after transplantation.

METHODS

A case series describing the successful outcome of kidney transplantation without prophylactic therapy in four adult patients with aHUS and a high risk of disease recurrence. Patients received a living donor kidney and immunosuppression consisting of basiliximab induction, low-dose tacrolimus, prednisone and mycophenolate mofetil. Patients received a statin, and were targeted to a low blood pressure preferably using blockers of the renin-angiotensin system.

RESULTS

After a follow-up of 16-21 months, none of the patients developed recurrent aHUS. Also, no rejection was observed.

CONCLUSIONS

Kidney transplantation in adult patients with aHUS can be successful without prophylactic eculizumab, using a protocol that minimises cold ischaemia time, reduces the risk of rejection and provides endothelial protection. Our data suggest that in patients with aHUS, controlled trials are needed to demonstrate the optimal strategy.

Clinical value of inflammatory urinary biomarkers in overt diabetic nephropathy: a prospective study

AIMS

The evolution of diabetic nephropathy is incompletely accounted by current clinical tools. New biomarkers may refine patient assessment and help monitor therapy. We compared the added predictive value of 7 candidate inflammatory urinary biomarkers to known risk factors of progression.

METHODS

We prospectively followed 83 patients with overt diabetic nephropathy for a median 2.1 years and obtained repeated measurements of proteinuria, IL-1β, IL-6, IL-8, MCP-1, TNF-α, TGF-β1, and PAI-1.

RESULTS

Patients had an initial estimated glomerular filtration rate of 25 ± 9 mL/min/1.73 m(2), blood pressure of 142/69 mmHg and used a median of 4 anti-hypertensive medications over the course of the study. The observed rate of renal function decline was 2.9 ± 3.0 mL/min/1.73 m(2)/year. All urinary biomarkers levels were collinear and for each one except IL-1β, elevated levels predicted a more rapid progression. MCP-1 was the only biomarker increasing during follow-up, which also correlated with a worst outcome. Using multivariate linear regression adjusting for clinical risk factors of progression, urinary MCP-1 and TGF-β1 predicted progression independently and additively to the degree of proteinuria. We dichotomized these 3 biomarkers and observed a renal function decline with 0, 1, 2 or 3 elevated biomarkers of -0.8 ± 1.4, -2.1 ± 2.1, -4.2 ± 2.8 and -6.0 ± 2.8 mL/min/1.73 m(2)/year, respectively (p<0.001).

CONCLUSIONS

Multiple urinary biomarkers predict outcome in overt diabetic nephropathy. However, urinary MCP-1 and TGF-β1 are also independent and additive to proteinuria in predicting the rate of renal function decline and could serve as useful clinical tools in patient risk stratification.

[A jaundiced patient with acute kidney injury]

A 56-year-old man with obstructive icterus due to pancreas cysts presented with acute kidney insufficiency and bilirubin casts in the urinary sediment as a sign of bilirubin-associated acute kidney injury.

[Renal manifestation of Henoch-Schönlein purpura in adults]

For a few months a 19-year-old man had red maculae on both feet which spread once a month. He also had macroscopic haematuria. A 45-year-old man was admitted with a deep venous thrombosis of his left leg and acute renal insufficiency. He had a history of purpura on his legs, a skin biopsy of which had shown leukoclastic vasculitis. A 37-year-old woman had persistent hypertension and nephrotic syndrome following childbirth. She had suffered from skin problems and oedema since the age of 6. All 3 patients proved to have Henoch-Schönlein purpura with renal symptoms. In principle Henoch-Schönlein purpura is treated with supportive measures, but if there is renal involvement it is advised to start symptomatic treatment of proteinuria and blood pressure. Depending on the degree of renal involvement, immunosuppresives may also be prescribed.

Tuberculous peritonitis during infliximab therapy

Reactivation of tuberculosis is a severe side effect of anti-TNF treatment. Especially extrapulmonary forms of tuberculosis may occur, which are difficult to diagnose. The diagnosis may be obtained by a thorough search for Mycobacterium tuberculosis. We describe two patients who developed tuberculous peritonitis after infliximab therapy that was prescribed for treatment of rheumatoid arthritis. These cases illustrate that tuberculous peritonitis has a nonspecific clinical manifestation and that Mycobacteria can be difficult to find in ascites fluid. For this reason, tuberculostatic therapy has to be started in case of clinical suspicion. Before starting infliximab therapy, the patient must be thoroughly screened for the presence of (latent) tuberculosis.

[Estimating renal function with formulas]

A glomerular filtration rate (GFR) <60 ml/min/1.73 m2 is associated with an increased risk of cardiovascular disease and renal insufficiency. The formula of the 'Modification of diet in renal disease' (MDRD) study is derived from plasma-creatinine concentrations and estimates GFR based on age, sex and race. Many clinical laboratories have started to report estimated GFR using this formula, which may lead to earlier recognition of chronic kidney disease. Clinicians should understand for which patients the MDRD formula may be appropriate and be aware of its limitations.

Estimation of renal function in subjects with normal serum creatinine levels: influence of age and body mass index

BACKGROUND

The Cockcroft-Gault (CG) and simplified Modification of Diet in Renal Disease (MDRD) formulas are the most widely used estimates of renal function. The influence of age and body mass index (BMI) on the performance of these equations was analyzed in 850 subjects with serum creatinine levels less than 1.5 mg/dL (<133 micromol/L).

METHODS

Glomerular filtration rate (GFR) was measured as urinary clearance of continuously infused technetium Tc 99m-labeled diethylene triaminopentaacetic acid. Performance was assessed as bias, precision, and accuracy.

RESULTS

In the total population, the CG and MDRD calculations based on enzymatic measurement of serum creatinine (which is constantly less than that obtained by using the alkaline picrate [Jaffé] method) significantly underestimated GFR by 4.9 and 12.4 mL/min/1.73 m2 (0.08 and 0.21 mL/s/1.73 m2), respectively. In patients 65 years and older, underestimation by means of the CG formula was enhanced, whereas that by means of the MDRD formula was blunted, compared with the group younger than 65 years (-11.3 versus -3.7 mL/min/1.73 m2 [-0.19 versus -0.06 mL/s/1.73 m2] for CG and -3.7 versus -14.0 mL/min/1.73 m2 [-0.06 versus -0.23 mL/s/1.73 m2] for MDRD). GFR was underestimated to a large extent by means of the MDRD equation irrespective of BMI. Conversely, the underestimation by means of the CG formula found in lean people (-13.0 mL/min/1.73 m2 [-0.22 mL/s/1.73 m2]) was blunted in overweight people (BMI, 25 to 30 kg/m2) and reversed to overestimation (+10.1 mL/min/1.73 m2 [+0.17 mL/s/1.73 m2]) in obese subjects (BMI > 30 kg/m2).

CONCLUSION

As suggested by estimations obtained using enzymatic serum creatinine measurement, the MDRD equation may be the estimation of choice in elderly patients, whereas the CG estimate is preferable in subjects younger than 65 years. Nevertheless, when obesity is present, no reliable estimation can be obtained by using the CG or MDRD formula.

The association between atherosclerotic risk factors and renal function in the general population

BACKGROUND

Generalized atherosclerosis is increasingly recognized as an important cause of end-stage renal disease (ESRD). We questioned to what extent atherosclerotic risk factors determine renal function in the general population.

METHODS

We used baseline data of the Prevention of Renal and Vascular End-Stage Disease (PREVEND) Study. A total of 8592 subjects, aged 28 to 75 years old, visited the outpatient clinic for blood pressure and anthropometric measurements, fasting blood sampling, and delivery of two 24-hour urine collections for creatinine clearance and albuminuria calculations. Design-based multivariate linear regression was used to estimate renal function.

RESULTS

In a multivariate model, male gender and body mass index (BMI) were associated with a higher renal function, while increasing diastolic blood pressure, serum triglycerides, use of antihypertensive or lipid-lowering medication were associated with a lower renal function. Age, systolic blood pressure, and plasma glucose showed an inverse U-shaped relationship with renal function. Cholesterol/high-density lipoprotein (HDL) ratio, smoking, and antidiabetic medication did not contribute to explain renal function. The atherosclerotic risk factors were related to renal function independently of albuminuria or C-reactive protein (CRP). Albuminuria and CRP itself were also related to renal function. Following gender and age, BMI, urinary albumin excretion (UAE), and plasma glucose had the strongest relation with renal function.

CONCLUSION

We conclude that differences in renal function in the general population are (partly) explained by various atherosclerotic risk factors. Some risk factors are associated with elevated filtration, some with an impaired filtration, and others with both a higher and a lower renal function.

Elevated Pulse Pressure Is Associated With Low Renal Function in Elderly Patients With Isolated Systolic Hypertension

In the past decade, pulse pressure has emerged as a strong predictor of cardiovascular morbidity and mortality. During aging, elevation of pulse pressure is a consequence of stiffening of the arterial wall. The relationship between pulse pressure and the renal aging process was studied in a cohort of 212 patients with never-treated isolated systolic hypertension. Glomerular filtration rate and effective renal plasma flow were measured using constant infusion of technetium 99m ( 99m Tc)-DTPA and 131 I-ortho-iodohippurate, respectively, and timed urine collections. The relationship between pulse pressure and renal function was studied using a linear regression model in the total population and in 40 to 49, 50 to 59, and 60 years and older age categories. In the whole population, there was an inverse relationship between pulse pressure and glomerular filtration rate; however, this relation did not persist after adjustment for age. In fact, the inverse relationship between pulse pressure and glomerular filtration rate was only present in patients 60 years of age or older. This relationship in elderly patients remained after adjustment for age, gender, MAP, and cardiovascular risk factors ( P =0.006). It is suggested that pulse pressure, a marker of arterial stiffening, may have a detrimental influence on the age-related decline in glomerular filtration rate, after 60 years of age in patients with never-treated isolated systolic hypertension.

The validity of screening based on spot morning urine samples to detect subjects with microalbuminuria in the general population

BACKGROUND

No study has yet investigated the validity of prescreening by albumin measurements in a spot morning urine sample to identify in the general population subjects with microalbuminuria. We therefore tested the diagnostic performance of urinary albumin concentration (UAC) and albumin-creatinine ratio (ACR), measured in a spot morning urine sample, in predicting a urinary albumin excretion (UAE) > or =30 mg in subsequent 24-hour urines (microalbuminuria).

METHODS

Subjects (2527) participating in the PREVEND study, a representative sample from the general population, collected a spot morning urine sample and, on average, 77 days later, two 24-hour urine collections.

RESULTS

The ROC curve of UAC in predicting microalbuminuria has an area-under-the-curve of 0.92 with a discriminator value of 11.2 mg/L. Using this cut-off value for UAC, sensitivity in predicting microalbuminuria is 85.0%, and specificity 85.0%. For ACR these values are, respectively: area-under-the-curve 0.93, discriminator value 9.9 mg/g, sensitivity 87.6%, and specificity 87.5%. Sensitivity for UAC in predicting microalbuminuria does not differ significantly from the sensitivity for ACR, whereas the difference between the specificities of UAC and ACR reaches statistical significance, but is numerically very small. In various subgroups characterized by differences in urinary creatinine excretion, the area-under-the-ROC curve, sensitivity, as well as specificity, do not increase relevantly compared to the results in the overall study population. This holds true for ACR as well as UAC.

CONCLUSION

The diagnostic performance of measuring UAC in a spot morning urine sample in predicting microalbuminuria in subsequent 24-hour urine collections is satisfactory, and, moreover, comparable to that of measuring ACR. In order to keep the burden and costs involved in population screening for microalbuminuria as low as possible, we therefore propose prescreening by measuring UAC in a spot morning urine sample. Those subjects with a UAC above a certain predefined level (e.g., 11 mg/L) should be asked to collect timed urine samples.

An elevated urinary albumin excretion predicts de novo development of renal function impairment in the general population

BACKGROUND

We questioned which factors determine the risk for developing renal function impairment. To that purpose, we studied the incidence of newly diagnosed impaired renal function (GFR <60 mL/min/1.73m2) in the PREVEND cohort (N=8592), which is enriched for the presence of albuminuria, and which was first studied in 1997-1998. Of this cohort, 6894 subjects were studied again four years later.

METHODS

Subjects with known renal disease, GFR <60 mL/min, missing GFR values, or sediment abnormalities at the first screening were excluded from the present analysis (N=872). We examined whether albuminuria is associated with the de novo development of an impaired renal function. GFR was 90.3 (SD 16.3) mL/min/1.73m2 at baseline, and 11.6% of the subjects had an albuminuria of more than 30 mg/day.

RESULTS

After a follow-up of four years, 253 subjects (4.2%) were found to have a GFR <60 mL/min/1.73m2. The subjects with newly diagnosed impaired GFR were older, had a higher blood pressure, serum cholesterol, plasma glucose, and urinary albumin excretion at the first examination, and had a lower GFR to start with than those with a GFR >60 at the second evaluation. Subjects with de novo impaired GFR had a comparable BMI and smoked less frequently compared with subjects with GFR >60. In multivariate analysis, urinary albumin excretion was independently predictive for the risk of developing an impaired GFR (P=0.001).

CONCLUSION

Also in the general population, measurement of urinary albumin excretion may prove to be a valuable tool to detect subjects at risk for later development of renal failure, independent of the presence of other cardiovascular risk factors.

Factors influencing serum cystatin C levels other than renal function and the impact on renal function measurement

BACKGROUND

It is well known that serum creatinine may be used as a marker of renal function only if taking into account factors that influence creatinine production, such as age, gender, and weight. Serum cystatin C has been proposed as a potentially superior marker than serum creatinine, because serum cystatin C level is believed to be produced at a constant rate and not to be affected by such factors. However, there are limited data on factors that may influence serum cystatin C levels, and there are limited data comparing cystatin C-based estimates of renal function with creatinine-based estimates that adjust for such factors, especially in individuals with normal, or mildly reduced, renal function.

METHODS

This was a cross-sectional study of 8058 inhabitants of the city of Groningen, The Netherlands, 28 to 75 years of age. Serum cystatin C and serum creatinine levels were measured, and creatinine clearance was determined from the average of two separate 24-hour urine collections. We performed multivariate analyses to identify factors independently associated with serum cystatin C levels after adjusting for creatinine clearance. Then, partial Spearman correlations were obtained after adjusting for factors that may influence serum cystatin C and creatinine levels. We also compared the goodness-of-fit (R(2)) of different multivariate linear regression models including serum cystatin C level and serum creatinine level for the outcome of creatinine clearance.

RESULTS

Older age, male gender, greater weight, greater height, current cigarette smoking, and higher serum C-reactive protein (CRP) levels were independently associated with higher serum cystatin C levels after adjusting for creatinine clearance. After adjusting for age, weight, and gender, the partial Spearman correlations between creatinine and, respectively, serum cystatin C level and serum creatinine level were -0.29 (P < 0.001) and -0.42 (P < 0.001), respectively. The R(2) values for serum cystatin C level and serum creatinine level adjusted for age, weight, and gender were 0.38 and 0.42, respectively. The addition of cigarette smoking and serum CRP levels did not improve the R(2) value for the multivariate serum cystatin C-based model.

CONCLUSION

Serum cystatin C appears to be influenced by factors other than renal function alone. In addition, we found no evidence that multivariate serum cystatin C-based estimates of renal function are superior to multivariate serum creatinine-based estimates.

Sodium intake affects urinary albumin excretion especially in overweight subjects

OBJECTIVES

To examine the relationship between sodium intake and urinary albumin excretion, being an established risk marker for later cardiovascular morbidity and mortality.

DESIGN

Cross-sectional cohort study using linear regression analysis. Setting. University hospital outpatient clinic.

SUBJECTS

A cohort drawn from the general population, consisting of 7850 subjects 28-75 years of age, all inhabitants of the city of Groningen, the Netherlands. The cohort is enriched for the presence of subjects with elevated urinary albumin concentration.

RESULTS

The results show a positive relationship between dietary sodium intake and urinary albumin excretion. The association was independent of other cardiovascular risk factors (such as sex, age, blood pressure, body mass index (BMI), waist-to-hip ratio, serum cholesterol, plasma glucose and smoking) and other food constituents (calcium, potassium and protein). The relationship between sodium intake and urinary albumin excretion was steeper in subjects with a higher BMI compared with a lower BMI.

CONCLUSIONS

Sodium intake is positively related to urinary albumin excretion. This relation is more pronounced in subjects with a higher BMI. These results suggest that high sodium intake may unfavourably influences cardiovascular prognosis especially in overweight and obese subjects.

Drawbacks of the use of indirect estimates of renal function to evaluate the effect of risk factors on renal function

Many epidemiologic studies presently aim to evaluate the effect of risk factors on renal function. As direct measurement of renal function is cumbersome to perform, epidemiologic studies generally use an indirect estimate of renal function. The consequences of using different methods of renal function measurement in studies that evaluate the effect of cardiovascular risk factors on renal function were questioned. Data of the 8592 Prevention of Renal and Vascular End-stage Disease study participants, in whom the association was plotted between various cardiovascular risk factors and renal function measured either by creatinine clearance based on two 24-h urine collections or by the Cockcroft-Gault or Modification of Diet in Renal Disease formula were used. A repeated measurement analysis was used to compare the slopes of the linear regression lines of the risk factors and the different methods of renal function measurements. The relation between cardiovascular risk factors and renal function seems to be different when different methods for renal function are used. This was most pronounced for age, weight, and body mass index and less pronounced (but still statistical significant) for BP, cholesterol, and glucose. The relation between weight or body mass index and renal function showed completely different directions, depending on the renal function method used. In conclusion, the interpretation of the relation of cardiovascular risk factors and renal function is affected by the method selected to estimate renal function. For studying the relation of risk factors and renal function in large population studies, indirect estimates of renal function should be used with caution.

Cardiovascular risk factors are differently associated with urinary albumin excretion in men and women

Cardiovascular morbidity and mortality is not equally distributed among genders, men being more affected than women. It is not clear whether this is only related to a higher prevalence of the cardiovascular risk factors or to a similar prevalence of the risk factors as in women but a greater vascular susceptibility to these risk factors in men. This was tested by studying the association between various cardiovascular risk factors and urinary albumin excretion (UAE) in a large cohort of male and female subjects. While the prevalence of smoking and hypercholesterolemia was comparable between the genders, obesity was more common in women, and diabetes and hypertension were more frequent in men. The prevalence of microalbuminuria was about twofold higher in men. Interestingly, for a given level of any risk factor, UAE was higher in men than in women. On multivariate analysis with UAE as the dependent variable, an interaction with gender was found for the risk factors age, body mass index, and plasma glucose. Thus, for a higher age, body mass index, and glucose, the UAE is significantly increased in men when compared with women. It is concluded that gender differences exist in the association between cardiovascular risk factors and UAE. This is consistent with a larger vascular susceptibility to these risk factors in men as compared with women.

The reliability of different formulae to predict creatinine clearance

OBJECTIVES

Creatinine clearance (CCR) is a commonly used tool to measure glomerular filtration rate (GFR) in clinical practice. This tool requires collection of 24-h urine, which is quite bothersome. Several different formulae have been used to estimate GFR using plasma creatinine and other easy formulae to obtain biometrical data. We examined 10 formulae and compared them with actually measured CCR in a large sample of the general population.

DESIGN

Cross-sectional cohort study.

SETTING

University hospital outpatient clinic, a population based study.

SUBJECTS

A total of 8592 inhabitants of the city of Groningen, 28-75 years of age. The cohort is enriched for microalbuminuria.

RESULTS

In general, the formulae did not give an accurate estimation of CCR, particularly not in male and in obese subjects. Six formulae, including the Cockcroft-Gault gave a fairly good estimation of CCR in the overall population and in subgroups of specific gender, body mass index and age. All formulae however, gave an underestimation of the measured CCR in higher ranges of CCR and an overestimation in the lower ranges. Moreover, the age-related decline of CCR is hard to approximate with a formula.

CONCLUSIONS

We conclude that formulae to estimate CCR in the general population, although giving a fairly good estimate of mean CCR, do not offer reliable data on CCR in the upper and lower ranges and do not adequately estimate the age-related decline in CCR.

Obesity and target organ damage: the kidney

Obesity is a risk marker for progressive renal function loss in patients with known renal disease. There is, however, increasing evidence that obesity may also damage the kidney in otherwise healthy subjects. There appears to be an intriguing parallel between the renal effects of obesity and those of diabetes. First, an increased renal blood flow and glomerular filtration rate has been described in obesity and, second, microalbuminuria is found to be related to obesity. These two events are known to predict future loss of renal function in diabetes. The mechanism responsible for the renal damage in obesity has not been established but there is evidence suggesting that this might be related to both hormonal changes as well as low-grade inflammation.

[Signs of miliary tuberculosis: which diagnostic tests and when to treat?]

Three patients, men aged 21, 57 and 53 years, presented with variable non-specific symptoms such as general malaise, weight loss, elevated temperature, abdominal pain, cough, pulmonary crepitations and elevated liver enzymes. Diffuse fine nodular infiltration was seen on chest radiography in the last two cases. The first patient refused to be tentatively treated with tuberculostatics and died. Mycobacterium tuberculosis complex grew on Löwenstein medium a week later. The two other patients received tuberculostatic treatment. The second patient recovered, while the third patient suffered a cerebrovascular accident on top of emaciation and respiratory insufficiency and died. In the Netherlands, currently more than one hundred patients with tuberculosis disease die each year. The disease is mostly seen in people from the high-risk groups for tuberculosis such as asylum seekers and immigrants. Even after extensive diagnostic procedures it can be difficult to obtain rapid bacteriological confirmation. When miliary tuberculosis is suspected it is important to carry out the complete range of tests (Ziehl Neelsen microscopy, PCR, Löwenstein cultivation) and to start therapy immediately and not to await the results of the diagnostic tests. However, in many cases this may still be too late, with an estimated mortality of 20%.

[Tuberculosis of the pancreas in a HIV-seropositive patient]

A 34-year-old man from Nigeria who had resided permanently in the Netherlands for five years had experienced fever, upper abdominal pain and weight loss for several months. He did not give the impression of being ill. A CT scan gave cause to suspect pancreatitis. An HIV test gave a positive result. Puncture of the accumulated fluid around the pancreas led to the diagnosis 'tuberculosis' (infection by Mycobacterium tuberculosis). Once the patient had made a good recovery with antituberculosis therapy, antiretroviral therapy was initiated, whereupon the number of CD4+ cells in the blood increased. Extrapulmonal tuberculosis is not unusual in HIV seropositive patients from countries with a high prevalence of tuberculosis. However, in such patients isolated tuberculosis of the pancreas is unusual and has not previously been described in the Netherlands. The diagnosis can be established following a CT guided puncture; tuberculosis is instantly suspected if the Ziehl-Neelsen stains are positive and the diagnosis can then be confirmed by a polymerase chain reaction (PCR) analysis and by culturing. Anti-retroviral therapy is withheld until response to anti-tuberculosis treatment is satisfactory.