Microalbuminuria in the US population: third National Health and Nutrition Examination Survey

Recent findings on the effects of marine-derived n-3 polyunsaturated fatty acids on urinary albumin excretion and renal function

Albuminuria (this includes microalbuminuria and macroalbuminuria) and reduced glomerular filtration rate are present not only in high-risk populations, but also in the general population. These manifestations of renal disease are associated with an increased risk of cardiovascular disease and may reflect subclinical vascular disease. Long-chain n-3 polyunsaturated fatty acids have been vigorously studied for their potential cardioprotective effects. These fatty acids reduce the levels of serum lipids, blood pressure, inflammation, and endothelial dysfunction, all of which are associated with albuminuria and renal impairment; therefore, marine-derived n-3 fatty acids may potentially play a role in their prevention. This report reviews the recent findings relating marine-derived n-3 fatty acids to urinary albumin excretion and renal function and their risk factors. Although some evidence suggests that marine-derived n-3 fatty acids are associated with a lower incidence of albuminuria in diabetes, there is inadequate evidence supporting their role in glomerular filtration.

Trends in relative mortality between Hispanic and non-Hispanic whites initiating dialysis: a retrospective study of the US Renal Data System

BACKGROUND

Hispanic patients undergoing long-term dialysis experience better survival compared with non-Hispanic whites. It is unknown whether this association differs by age, has changed over time, or is due to differential access to kidney transplantation.

STUDY DESIGN

National retrospective cohort study.

SETTING & PARTICIPANTS

Using the US Renal Data System, we identified 615,618 white patients 18 years or older who initiated dialysis therapy between January 1, 1995, and December 31, 2007.

PREDICTORS

Hispanic ethnicity (vs non-Hispanic whites), year of end-stage renal disease incidence, age (as potential effect modifier).

OUTCOMES

All-cause and cause-specific mortality.

RESULTS

We found that Hispanics initiating dialysis therapy experienced lower mortality, but age modified this association (P < 0.001). Compared with non-Hispanic whites, mortality in Hispanics was 33% lower at ages 18-39 years (adjusted cause-specific HR [HRcs], 0.67; 95% CI, 0.64-0.71) and 40-59 years (HRcs, 0.67; 95% CI, 0.66-0.68), 19% lower at ages 60-79 years (HRcs, 0.81; 95% CI, 0.80-0.82), and 6% lower at 80 years or older (HRcs, 0.94; 95% CI, 0.91-0.97). Accounting for the differential rates of kidney transplantation, the associations were attenuated markedly in the younger age strata; the survival benefit for Hispanics was reduced from 33% to 10% at ages 18-39 years (adjusted subdistribution-specific HR [HRsd], 0.90; 95% CI, 0.85-0.94) and from 33% to 19% among those aged 40-59 years (HRsd, 0.81; 95% CI, 0.80-0.83).

LIMITATIONS

Inability to analyze Hispanic subgroups that may experience heterogeneous mortality outcomes.

CONCLUSIONS

Overall, Hispanics experienced lower mortality, but differential access to kidney transplantation was responsible for much of the apparent survival benefit noted in younger Hispanics.

Prevalence of abnormal urinary albumin excretion in elderly people: a Spanish survey

OBJECTIVES

HERMEX is a population-based study, which tries to evaluate the prevalence of cardiovascular risk factors in the population of Extremadura, Spain. This report provides the data concerning albuminuria in the elderly people recruited in the survey.

DESIGN AND METHODS

3,402 subjects were randomly selected from the database of the Health Care System of Extremadura. The final sample included 2,813 subjects (mean age 51.2 years, 53.5 % female). Urinary albumin excretion rate (UAER) in the first morning urine sample was analyzed. Albuminuria was diagnosed when UAER (albumin-to-creatinine ratio) was ≥ 22 mg/g in men or ≥ 31 mg/g in women.

RESULTS

The prevalence of abnormal UAER in the elderly population was 10.9 % (microalbuminuria: 8.9 %; overt proteinuria: 1.8 %). The younger subjects showed a lower prevalence of microalbuminuria (3.4 %, p < 0.001). Elderly patients showed a higher prevalence of cardiovascular risk factors than the younger ones. The elderly had higher systolic blood pressure and pulse pressure than the younger ones. Furthermore, the elderly subjects had lower plasma levels of HDL cholesterol, but higher triglycerides, glucose, creatinine, and glycosylated hemoglobin; no differences were found for total and LDL cholesterol. When the prevalence of causes of microalbuminuria was compared between age groups, we found a sharp increase in diabetic and, especially, hypertensive patients in the elderly group. The multivariate analysis showed an independent association of microalbuminuria with systolic blood pressure and plasma creatinine.

CONCLUSIONS

A high prevalence of abnormal UAER in elderly people was detected in a randomly selected sample of Spanish general population. In most elderly patients, microalbuminuria was associated with high blood pressure and, less frequently, with diabetes mellitus.

Different definitions of prevalent hypertension impact: the clinical epidemiology of hypertension and attainment of Healthy People goals

Prevalent hypertension in National Health and Nutrition Examination Surveys (NHANES) is traditionally defined as blood pressure (BP) ≥140 mm Hg systolic and/or ≥90 diastolic and/or currently taking antihypertensive medications. When estimating prevalent hypertension, American Heart Association (AHA) statistical updates include the traditional definition of hypertension (tHTN) and untreated individuals with nonhypertensive BP told twice that they were hypertensive (nontraditional [ntHTN]). The characteristics of ntHTN and their impact on the clinical epidemiology of hypertension and Healthy People prevention and control goals are undefined. NHANES 1999-2002, 2003-2006, and 2007-2010 were analyzed. The ntHTN group was younger and had less diabetes and lower BP than the tHTN group but higher BP than the normotensive group. When classifying ntHTN as hypertensive, prevalent hypertension increased approximately 3% and control 5% to 6% across NHANES periods. In 2007-2010, the Healthy People 2010 goal of controlling BP in 50% of all hypertensive patientss was attained when ntHTN was classified as hypertension (56.5% [95% confidence interval (CI), 54.2-58.7]) and nonhypertension (51.8% [95% CI, 49.6-53.9]). When including ntHTN in prevalent hypertension estimates, the Healthy People 2020 goal of controlling BP in 60% of hypertensive patients becomes more attainable, whereas reducing prevalent hypertension to 26.9% (31.8% [95% CI, 30.5-33.1]) vs 28.7% [95% CI, 27.5-30.0]) becomes more challenging.

High pulse pressure and metabolic syndrome are associated with proteinuria in young adult women

Background

Obesity and metabolic syndrome play causative roles in the increasing prevalence of proteinuria in the general population. However, in young adult women the clinical significance of incidentally discovered proteinuria and its association with metabolic syndrome are unclear. We investigated the prevalence and risk factors for proteinuria in this population.

Methods

A total of 10,385 women aged 20 to 39 years who underwent health screenings were surveyed. Each patient was tested for proteinuria with a dipstick (−, ±, 1+, 2+, or 3+), and proteinuria was defined as 1+ or greater. Persistent proteinuria was established by confirming proteinuria in a subsequent test. Metabolic syndrome was defined in accordance with the updated National Cholesterol Education Program Adult Treatment Panel III criteria for Asia.

Results

The mean age was 28.9 ± 5.5 years, and the prevalence of persistent proteinuria was 1.0%. Among these subjects with persistent proteinuria, obesity and metabolic syndrome were found in 10.4% and 5.2%, respectively. Metabolic syndrome, as well as its components of hypertension, hyperglycemia, central obesity, low high-density lipoprotein levels, and high triglyceride levels, was closely related to the presence of proteinuria. In addition, a wide pulse pressure of ≥40 mmHg was another independent risk factor for proteinuria [odds ratio (OR) 3.29, 95% confidence interval (CI) 1.03–11.91)]. This had an additive effect on metabolic syndrome in terms of predicting proteinuria. Even in subjects without metabolic syndrome, the influence of an increased pulse pressure was consistent (OR 2.75, 95% CI 1.03–8.61).

Conclusions

Specific attention to proteinuria may be necessary in asymptomatic young women aged 20 to 39 years if they have metabolic syndrome or a wide pulse pressure.

Assessment of microalbuminuria for early diagnosis and risk prediction in dengue infections

BACKGROUND

Dengue is the most important arboviral infection of humans. Following an initial febrile period, a small proportion of infected patients develop a vasculopathy, with children at particular risk for severe vascular leakage and shock. Differentiation between dengue and other common childhood illnesses is difficult during the early febrile phase, and risk prediction for development of shock is poor. The presence of microalbuminuria is recognized as a useful early predictor for subsequent complications in a number of other disorders with vascular involvement. Significant proteinuria occurs in association with dengue shock syndrome and it is possible that early-phase microalbuminuria may be helpful both for diagnosis of dengue and for identification of patients likely to develop severe disease.

METHODOLOGY/PRINCIPAL FINDINGS

We measured formal urine albumin to creatinine ratios (UACRs) in daily samples obtained from a large cohort of children with suspected dengue recruited at two outpatient clinics in Ho Chi Minh City, Vietnam. Although UACRs were increased in the 465 confirmed dengue patients, with a significant time trend showing peak values around the critical period for dengue-associated plasma leakage, urine albumin excretion was also increased in the comparison group of 391 patients with other febrile illnesses (OFI). The dengue patients generally had higher UACRs than the OFI patients, but microalbuminuria, using the conventional cutoff of 30 mg albumin/g creatinine discriminated poorly between the two diagnostic groups in the early febrile phase. Secondly UACRs did not prove useful in predicting either development of warning signs for severe dengue or need for hospitalization.

CONCLUSION/SIGNIFICANCE

Low-level albuminuria is common, even in relatively mild dengue infections, but is also present in many OFIs. Simple point-of-care UACR tests are unlikely to be useful for early diagnosis or risk prediction in dengue endemic areas.

Albuminuria prevalence in first morning void compared with previous random urine from adults in the National Health and Nutrition Examination Survey, 2009-2010

BACKGROUND

Albuminuria, defined as urine albumin/creatinine ratio (ACR) ≥30 mg/g, is a diagnostic component of chronic kidney disease (CKD). National estimates of ACR and CKD prevalence have been based on single random urine samples. Although 2 urine samples or a first morning void are known to produce different estimates of ACR, the impact of differing urine sampling schemes on nationally estimated rates of CKD is unknown.

METHODS

In 2009-2010, the National Health and Nutrition Examination Survey (NHANES) participants provided 2 untimed urine samples for sequential ACR measurement: an initial random urine collected in the NHANES mobile examination center and a subsequent first morning void collected at home. Rates of albuminuria were calculated in the overall population and broken down by demographics, diagnosed diabetes and hypertension status, and estimated glomerular filtration rate (eGFR).

RESULTS

Overall, 43.5% of adults with increased ACR (≥30 mg/g) in a random urine also had increased ACR in a first morning urine. This percentage was higher among individuals ≥50 years old (48.9%), males (53.3%), participants with diagnosed diabetes (56.3%) and hypertension (51.5%), and eGFR <60 mL/min/1.72m(2) (56.9%). The use of confirmed increased ACR (defined as the presence of ACR ≥30 mg/g in both samples taken within 10 days) to define CKD resulted in a lower overall prevalence (11.6%) than first morning urine (12.7%) or random spot urine only (15.2%).

CONCLUSIONS

ACR measured on random urine samples appears to overestimate the prevalence of albuminuria compared to first morning urine collections.

Factors affecting levels of urinary albumin excretion in the general population of Spain: the Di@bet.es study

The present study was undertaken to examine the prevalence of urinary ACR (albumin/creatinine ratio) >30 mg/g and the associated clinical and environmental factors in a representative sample of the population of Spain. Di@bet.es study is a national, cross-sectional population-based survey conducted in 2009-2010. Clinical, metabolic, socio-demographic, anthropometric data and information about lifestyle habit were collected. Those subjects without KDM (known diabetes mellitus) were given an OGTT (oral glucose tolerance test). Albumin and creatinine were measured in a urinary sample and ACR was calculated. The population prevalence of ACR >30 mg/g was 7.65% (adjusted for sex and age). The prevalence of ACR >30 mg/g increased with age (P<0.001). Subjects with carbohydrate metabolism disorders had a greater prevalence of ACR >30 mg/g but after being adjusted for age, sex and hypertension, was significant only in those subjects with UKDM (unknown diabetes mellitus) {OR (odd ratio), 2.07 [95% CI (confidence interval), 1.38-3.09]; P<0.001] and KDM [OR, 3.55 (95% CI, 2.63-4.80); P<0.001]. Prevalence of ACR >30 mg/g was associated with hypertension [OR, 1.48 (95% CI, 1.12-1.95); P=0.001], HOMA-IR (homoeostasis model assessment of insulin resistance) [OR, 1.47 (95% CI, 1.13-1.92); P≤0.01], metabolic syndrome [OR, 2.17 (95% CI, 1.72-2.72); P<0.001], smoking [OR, 1.40 (95% CI, 1.06-1.83); P≤0.05], physical activity [OR, 0.68 (95% CI, 0.54-0.88); P≤0.01] and consumption of fish [OR, 0.38 (95% CI, 0.18-0.78); P≤0.01]. This is the first study that reports the prevalence of ACR >30 mg/g in the Spanish population. The association between clinical variables and other potentially modifiable environmental variables contribute jointly, and sometimes interactively, to the explanation of prevalence of ACR >30 mg/g. Many of these risk factors are susceptible to intervention.

Increased cardiovascular risk after pre-eclampsia in women with dysglycaemia

AIMS

Compared with women with uncomplicated pregnancies, women with a history of pre-eclampsia have two to five times the risk of cardiovascular disease. It is not known whether this risk is related to albuminuria, a known cardiovascular risk factor that is part of the definition of pre-eclampsia and that often persists after delivery. Our objective was to determine if the high risk of cardiovascular disease in women with pre-eclampsia is accounted for by known cardiovascular risk factors including albuminuria.

METHODS

We performed a cross-sectional analysis of 4080 dysglycaemic women enrolled in a large randomized controlled trial who provided an obstetric history and had at least one delivery. Blood pressure, height, weight, waist circumference and hip circumference were measured. An oral glucose tolerance test, lipids, an electrocardiogram and an albumin/creatinine ratio from a first morning urine sample were obtained.

RESULTS

There were 3613 women with no history of pre-eclampsia during their pregnancies, 108 with severe pre-eclampsia and 359 with non-severe pre-eclampsia. Women with a history of severe pre-eclampsia had higher rates of previous cardiovascular disease than women with non-severe pre-eclampsia or women without pre-eclampsia (87, 72 and 72%, P = 0.0019). The high risk of previous cardiovascular disease in women with a history of severe pre-eclampsia (odds ratio 2.67, 95% CI 1.52-4.70) persisted after adjustment for albuminuria (odds ratio 2.74, 95% CI 1.55-4.83) and also after adjusting for other covariates including albuminuria (odds ratio 3.03, 95% CI 1.69-5.44).

CONCLUSION

Even after accounting for cardiovascular risk factors including albuminuria, a history of severe pre-eclampsia is independently associated with a threefold higher risk of cardiovascular disease.

Albuminuria and hyperhomocysteinemia as cardiovascular risk factors in potentially healthy soldiers: A long-term observation

Background

To assess the relations between albuminuria and selected cardiovascular risk factors.

Material/Methods

The study population comprised 200 apparently healthy soldiers aged 28.8±8.1, observed for 36 months.

Results

Albuminuria was revealed in 9% of the studied group at the beginning of the study and in 12.7% at the end of the observation. Albumins increased from 97.0±61.0 mg/24 hours to 165.0±25.7 mg/24 hours after 36 months of observation. The increase of diastolic blood pressure, body mass, C-reactive protein (CRP), and low-density lipoprotein (LDL) was found in the “albuminuria subgroup” after 3 years of observation. This subgroup also presented significantly higher homocysteine and CRP serum concentrations in comparison with the “non-albuminuria group” in the first phase of the study and after 3 years of follow-up.

Conclusions

Albuminuria was found to be a relatively frequent and persistent abnormality in the studied group. The study demonstrated the relationship between the occurrence and the severity of albuminuria and selected biochemical and demographic cardiovascular risk factors. Determination of albuminuria is a useful, early marker of cardiovascular risk in young male professional soldiers.

Low income and albuminuria among REGARDS (Reasons for Geographic and Racial Differences in Stroke) study participants

BACKGROUND

Albuminuria is an important risk factor for progressive chronic kidney disease (CKD) and is more prevalent in black than white adults. We sought to determine the association between low income and albuminuria and whether this association differs for blacks and whites.

STUDY DESIGN

Cross-sectional study.

SETTING & PARTICIPANTS

9,144 black and 13,684 white US adults 45 years and older in the population-based Reasons for Geographic and Racial Differences in Stroke (REGARDS) Study.

PREDICTORS

Self-reported annual household income category (≥$75,000, $35,000-$74,999, $20,000-$34,999, and <$20,000); black and white race.

OUTCOMES & MEASUREMENTS

Albuminuria defined as high (30-300 mg/g) or very high (>300 mg/g) urinary albumin-creatinine ratio (ACR). Multinomial logistic regression used to examine the race-stratified association between categories of income and albuminuria (normal, high, or very high ACR).

RESULTS

Overall, geometric mean ACR was 10.2 mg/g and was higher for blacks (11.8 mg/g) than whites (9.3 mg/g), P<0.001. Lower income was associated with a higher prevalence of albuminuria for both whites and blacks in unadjusted analyses. After adjustment for demographics, lifestyle factors, comorbid illnesses, and estimated glomerular filtration rate, there was a trend toward a stronger association between lower income levels and high ACR in blacks (ORs of 1.38 [95% CI, 1.07-1.77], 1.36 [95% CI, 1.05-1.75], and 1.58 [95% CI, 1.21-2.05] for income levels of $35,000-$74,999, $20,000-$34,999, and <$20,000, respectively; reference group is those with income≥$75,000) compared with whites (ORs of 0.95 [95% CI, 0.81-1.12], 0.95 [95% CI, 0.79-1.14], and 1.26 [95% CI, 1.02-1.55], respectively); P interaction=0.08 between race and income. Results were similar for very high ACR and subgroups of participants with diabetes or hypertension.

LIMITATIONS

Cross-sectional design; not all REGARDS participants provided their annual income.

CONCLUSIONS

Lower income may be associated more strongly with albuminuria in blacks than whites and may be a determinant of racial disparities in albuminuria.

Impact of the number of blood pressure measurements on blood pressure classification in US adults: NHANES 1999-2008

Clinical guidelines recommend averaging ≥ 2 blood pressure (BP) measurements on each visit. Only one BP is measured on many clinical visits, especially if the value is <120/<80 mm Hg, ie, normal. The impact of this practice on accurate assignment of BP category is incompletely defined. Data were analyzed from 22,641 adults 18 years and older who had 3 BP readings in the National Health and Nutrition Examination Surveys 1999-2008. BP category defined by initial measurement was compared with the category determined by mean of the first and second, first through third, and second and third readings. Among 8553 nonhypertensive patients with initial BP <120/<80 mm Hg, 2.9%, 3.3%, and 6.7%, respectively, were reclassified as prehypertensive, ie, BP 120-139/80-89 mm Hg, and two patients as stage 1 hypertension (140-159/90-99 mm Hg). In 733 treated hypertensive patients with initial BP <120/<80 mm Hg, 5.1%-8.9% were reclassified as prehypertensive and only one patient as hypertensive. Among nonhypertensive and hypertensive patients with initial BP in the prehypertensive range, 8.0%-23.6% were reclassified as normal. Among stage 1 and 2 hypertensive patients based on initial BP, 18.2%-33.5% were reclassified to lower BP categories. By multivariable logistic regression, older age and higher systolic and diastolic BP were associated with reclassification to a lower BP category. In nonhypertensive and hypertensive patients with normal initial BP values, one BP measurement appears adequate as <10% are re-classified as prehypertensive and <0.5% as hypertensive. In contrast, patients with an initial BP above normal are often reclassified to a lower category, which supports recommendations for additional measurements.

The association of albumin/creatinine ratio with postoperative AKI in children undergoing cardiac surgery

BACKGROUND AND OBJECTIVES

This study determined if preoperative and postoperative urine albumin/creatinine ratios (ACRs) predict postoperative AKI in children undergoing cardiac surgery (CS).

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

This was a three-center, prospective study (2007-2009) of 294 children undergoing CS (n=145 aged <2 years). Urine ACR was measured preoperatively and 0-6 hours after intensive care unit arrival. AKI outcomes were based on the Acute Kidney Injury Network serum creatinine (SCr) criteria (stage 1 AKI, ≥50% or 0.3 mg/dl SCr rise from baseline; and stage 2 or worse AKI, ≥SCr doubling or dialysis). AKI was predicted using preoperative and postoperative ACRs and postoperative ACR performance was compared with other AKI biomarkers.

RESULTS

Preoperative ACR did not predict AKI in younger or older children. In children aged <2 years, first postoperative ACR ≥908 mg/g (103 mg/mmol) predicted stage 2 AKI development (adjusted relative risk, 3.4; 95% confidence interval, 1.2-9.4). In children aged ≥2 years, postoperative ACR ≥169 mg/g (19.1 mg/mmol) predicted stage 1 AKI (adjusted relative risk, 2.1; 95% confidence interval, 1.1-4.1). In children aged ≥2 years, first postoperative ACR improved AKI prediction from other biomarker and clinical prediction models, estimated by net reclassification improvement (P≤0.03), but only when serum cystatin C was also included in the model.

CONCLUSIONS

Postoperative ACR is a readily available early diagnostic test for AKI after pediatric CS that performs similarly to other AKI biomarkers; however, its use is enhanced in children aged ≥2 years and in combination with serum cystatin C.

Prevalence of microalbuminuria among secondary school children

BACKGROUND

Microalbuminuria is an early sign of kidney and cardiovascular damage. Therefore, early detection in asymptomatic individuals may be helpful in preventing deterioration in renal function.

METHODS

We carried out a cross-sectional study of 820 secondary school students aged 10 - 19 years from September to November 2008. The urine samples of 615 (75.0%) without overt proteinuria and haematuria were tested for microalbuminuria using the micral test strips. Values of greater than 20mg/L were considered positive.

RESULTS

There were 299 (48.6%) males and 316 (51.4%) females, with a M:F ratio of 1:1.1. The prevalence of microalbuminuria as seen in 214 of the students was 33.2%. It was significantly higher in females (45.3%), obese subjects (35.4%), those with hypertension (70.6%), those with positive family history of hypertension (59.5%), and diabetes mellitus (46.4%). Microalbuminuria was found in 1 of the 2 subjects who had features of DM and in one subject with sickle cell anemia.

CONCLUSION

The prevalence of microalbuminuria in Nigerian adolescents is high. We recommend routine screening for microalbuminuria in adolescents for early detection and prevention of renal damage.

Combined association of albuminuria and cystatin C-based estimated GFR with mortality, coronary heart disease, and heart failure outcomes: the Atherosclerosis Risk in Communities (ARIC) Study

BACKGROUND

Serum cystatin C level has been shown to have a stronger association with clinical outcomes than serum creatinine level. However, little is known about the combined association of cystatin C-based estimated glomerular filtration rate (eGFR(cys)) and albuminuria with clinical outcomes, particularly at levels lower than current chronic kidney disease (CKD) cutoffs.

STUDY DESIGN

Prospective cohort.

SETTING & PARTICIPANTS

10,403 ARIC (Atherosclerosis Risk in Communities) Study participants followed up for a median of 10.2 years.

PREDICTOR

eGFR(cys), albuminuria.

OUTCOMES

Mortality, coronary heart disease (CHD), and heart failure, as well as a composite of any of these separate outcomes.

RESULTS

Both decreased eGFR(cys) and albuminuria were associated independently with the composite outcome, as well as mortality, CHD, and heart failure. Although eGFR(cys) of 75-89 mL/min/1.73 m(2) in the absence of albuminuria (albumin-creatinine ratio [ACR] <10 mg/g) or albuminuria with ACR of 10-29 mg/g with normal eGFR(cys) (90-104 mL/min/1.73 m(2)) was not associated significantly with any outcome compared with eGFR(cys) of 90-104 mL/min/1.73 m(2) and ACR <10 mg/g, the risk of each outcome was significantly higher in those with both eGFR(cys) of 75-89 mL/min/1.73 m(2) and ACR of 10-29 mg/g (for mortality, HR of 1.4 [95% CI, 1.1-2.0]; for CHD, HR of 1.9 [95% CI, 1.4-2.6]; for heart failure, HR of 1.8 [95% CI, 1.2-2.7]). Combining the 2 markers improved risk classification for all outcomes (P < 0.001), even in those without overt CKD.

LIMITATIONS

Only one measurement of cystatin C.

CONCLUSIONS

Mildly decreased eGFR(cys) and mild albuminuria independently contributed to the risk of mortality, CHD, and heart failure. Even minimally decreased eGFR(cys) (75-89 mL/min/1.73 m(2)) is associated with increased risk in the presence of mild albuminuria. Combining the 2 markers is useful for improved risk stratification even in those without clinical CKD.

Prevalence, risk factors and awareness of albuminuria on a Canadian First Nation: a community-based screening study

BACKGROUND

Both diabetic and non-diabetic end stage renal disease (ESRD) are more common among Canadian First Nations people than among the general Canadian population. The purpose of this research was to determine the prevalence of and risk factors for albuminuria in a Canadian First Nation population at high risk for ESRD and dialysis.

METHODS

Data from a community-based screening study of 483 residents of a Plains Ojibway First Nation in Manitoba was used. Participants provided random urine samples. Proteinuria was defined as any dipstick positive for protein (≥1 g/L) or those with ACR in the macroalbuminuric range (≥30 mg/mmol) on at least one sample. Microalbuminuria was defined as ACR ≥2 mg/mmol for males and ≥2.8 mg/mmol for females. Other measures included fasting glucose, haemoglobin A1c, triglycerides, cholesterol, blood pressure, height, weight and waist and hip circumferences.

RESULTS

Twenty percent of study participants had albuminuria, (5% proteinuria and 15% microalbuminuria). Of participants with diabetes, 42% (56/132) had albuminuria compared to 26% (7/27) among those with impaired fasting glucose and 10% (30/303) among those with normal glucose tolerance. Only 5.3% of those with albuminuria were aware of any degree of renal disease. In a multivariate logistic regression, independent associations with albuminuria were male gender [p = 0.002], increasing fasting glucose [p <0.0001], years diagnosed with diabetes [p = 0.03], increasing systolic blood pressure [p = 0.009], and increasing body mass index (BMI) [p = 0.04].

CONCLUSIONS

The independent association between BMI and albuminuria has not been previously reported among indigenous populations. There is a high prevalence of albuminuria in this Canadian First Nation population; the high proportion of patients with diabetes and undiagnosed kidney disease demonstrates the need for screening, education and intervention to halt the progression and development of albuminuria and ultimately ESRD and CVD.

Pattern of urinary albumin excretion in normotensive young and adolescent Indian women with polycystic ovary syndrome

OBJECTIVE

Polycystic ovarian syndrome (PCOS) is a clinically heterogeneous endocrine disorder affecting up to 4-8% of women of reproductive age. The aim of this study was to evaluate the presence of microalbuminuria in women with PCOS and study its correlation with the various metabolic, clinical, and hormonal parameters.

MATERIALS AND METHODS

A cross-sectional study involving 69 PCOS women was carried out in a tertiary care center hospital. The diagnosis of PCOS was made according to the Rotterdam criteria. Blood samples were collected in the follicular phase of the menstrual cycle and analyzed for fasting luteinizing hormone (LH), follicle stimulating hormone (FSH), prolactin (PRL), 17-hydroxyprogesterone (17-OHP), total testosterone (T), glucose, insulin, and lipid profile. Urinary albumin was measured in the first void spot urine sample.

RESULTS

The mean age of the subjects was 22.0 ± 4.1 years and 21.8 ± 4.7 years in normoalbuminuric and microalbuminuric groups, respectively. Urinary albumin excretion (UAE) varied from 5 mg/l to 100 mg/ml, with a median of 5 mg/l. Microalbuminuria was observed in 17/69 (24.6%) of subjects. The mean UAE was 3.65 ± 4.44 mg/l in the normoalbuminuria group versus 45.29 ± 22.74 mg/l in the microalbuminuria group. Upon univariate analysis, hip circumference, diastolic blood pressure, and fasting blood glucose showed significant correlations with urinary albumin concentration (r = 0.264, 0.264, and 0.551, respectively; P = 0.028, 0.029, and 0.000, respectively). No association between UAE and the usual cardiovascular risk factors could be found upon regression analysis.

CONCLUSION

About 24.6% of women with PCOS showed presence of microalbuminuria in the first void spot urine sample. Screening for the presence of microalbuminuria can help in early identification of a subset of PCOS women with a high risk for future CVD, who can be subjected to preventive strategies at the earliest. However, further studies are needed before recommending routine use of UAE in PCOS cases for the detection of CVD risk.

Beta blocker use in subjects with type 2 diabetes mellitus and systolic heart failure does not worsen glycaemic control

Background

The prognostic benefits of beta-blockers (BB) in patients with systolic heart failure (SHF) are known but despite this, in patients with diabetes they are underutilized. The aim of this study was to assess the effect of beta-blockers (BB) on glycaemic control in patients with Type 2 Diabetes (T2DM) and systolic heart failure (SHF) stratified to beta-1 selective (Bisoprolol) vs. nonselective BB (Carvedilol).

Methods

This observational, cohort study was conducted in patients with T2DM and SHF attending an Australian tertiary teaching hospital's heart failure services. The primary endpoint was glycaemic control measured by glycosylated haemoglobin (HbA1c) at initiation and top dose of BB. Secondary endpoints included microalbuminuria, changes in lipid profile and estimated glomerular filtration rate (eGFR).

Results

125 patients were assessed. Both groups were well matched for gender, NYHA class and use of guideline validated heart failure and diabetic medications. The mean treatment duration was 1.9 ± 1.1 years with carvedilol and 1.4 ± 1.0 years with bisoprolol (p = ns). The carvedilol group achieved a reduction in HbA1c (7.8 ± 0.21% to 7.3 ± 0.17%, p = 0.02) whereas the bisoprolol group showed no change in HbA1c (7.0 ± 0.20% to 6.9 ± 0.23%, p = 0.92). There was no significant difference in the change in HbA1c from baseline to peak BB dose in the carvedilol group compared to the bisoprolol group. There was a similar deterioration in eGFR, but no significant changes in lipid profile or microalbuminuria in both groups (p = ns).

Conclusion

BB use did not worsen glycaemic control, lipid profile or albuminuria status in subjects with SHF and T2DM. Carvedilol significantly improved glycemic control in subjects with SHF and T2DM and this improvement was non significantly better than that obtained with bisoprolol. BB's should not be withheld from patients with T2DM and SHF.

Increased expression of NAD(P)H oxidase subunit p67(phox) in the renal medulla contributes to excess oxidative stress and salt-sensitive hypertension

NAD(P)H oxidase has been shown to be important in the development of salt-sensitive hypertension. Here, we show that the expression of a subunit of NAD(P)H oxidase, p67(phox), was increased in response to a high-salt diet in the outer renal medulla of the Dahl salt-sensitive (SS) rat, an animal model for human salt-sensitive hypertension. The higher expression of p67(phox), not the other subunits observed, was associated with higher NAD(P)H oxidase activity and salt sensitivity in SS rats compared with a salt-resistant strain. Genetic mutations of the SS allele of p67(phox) were found in the promoter region and contributed to higher promoter activity than that of the salt-resistant strain. To verify the importance of p67(phox), we disrupted p67(phox) in SS rats using zinc-finger nucleases. These rats exhibited a significant reduction of salt-sensitive hypertension and renal medullary oxidative stress and injury. p67(phox) could represent a target for salt-sensitive hypertension therapy.

Hispanic ethnicity and vascular access use in patients initiating hemodialysis in the United States

BACKGROUND AND OBJECTIVES

Hispanics are the largest minority in the United States (comprising 16.3% of the US population) and have 1.5 times the age-, sex-, and race-adjusted incidence of ESRD compared with non-Hispanics. Poor health care access and low-quality care generally received by Hispanics are well documented. However, little is known regarding dialysis preparation of Hispanic patients with progressive CKD.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Using data from Medical Evidence Report form CMS-2728-U3, 321,996 adult patients of white or black race were identified who initiated hemodialysis (HD) between July 1, 2005 and December 31, 2008. The form captures Hispanic ethnicity, vascular access use at first outpatient HD, sociodemographic characteristics, and comorbidities. This study also examined whether use of an arteriovenous fistula (AVF) or graft (AVG) was reported.

RESULTS

AVF/AVG use was reported in 14.5% of Hispanics and 17.6% in non-Hispanics (P<0.001). The unadjusted prevalence ratio (PR) was 0.85 (95% confidence interval [95% CI], 0.83-0.88), indicating that Hispanics were 15% less likely to use AVG/AVF for their first outpatient HD. Adjustment for age, sex, and race, as well as a large number of comorbidities and frailty indicators, did not change this association (PR, 0.85; 95% CI, 0.83-0.88). Further adjustment for timing of first predialysis nephrology care, however, attenuated the PR by two-thirds (PR, 0.94; 95% CI, 0.92-0.97).

CONCLUSIONS

Hispanics are less likely to use arteriovenous access for first outpatient HD compared with non-Hispanics, which seems to be explained by variation in the access to predialysis nephrology care.

Association of family history of ESRD, prevalent albuminuria, and reduced GFR with incident ESRD

BACKGROUND

The contribution of albuminuria to the increased risk of incident end-stage renal disease (ESRD) in individuals with a family history of ESRD has not been well studied.

STUDY DESIGN

Prospective cohort study. STUDY SETTING & PARTICIPANTS: We analyzed data for family history of ESRD collected from 19,409 participants of the Renal REGARDS (Reasons for Geographic and Racial Differences in Stroke) cohort study.

PREDICTOR

Family history of ESRD was ascertained by asking "Has anyone in your immediate family ever been told that he or she had kidney failure? This would be someone who is on or had been on dialysis or someone who had a kidney transplant."

STUDY OUTCOMES

Incidence rate for ESRD.

MEASUREMENTS

Morning urine albumin-creatinine ratio (ACR) and estimated glomerular filtration rate (eGFR). Incident cases of ESRD were identified through the US Renal Data System.

RESULTS

A family history of ESRD was reported by 11.1% of participants. Mean eGFRs for those with and without a family history of ESRD were 87.5 ± 22.2 (SD) and 86.5 ± 19.3 mL/min/1.73 m(2), respectively (P = 0.05) and the respective geometric mean ACRs were 12.2 and 9.7 mg/g (P < 0.001). ESRD incidence rates for those with and without a family history of ESRD were 244.3 and 106.1/100,000 person-years, respectively. After adjusting for age, sex, and race, the ESRD HR for those with versus those without a family history of ESRD was 2.13 (95% CI, 1.18-3.83). Adjustment for comorbid conditions and socioeconomic status attenuated this association (HR, 1.82; 95% CI, 1.00-3.28), and further adjustment for baseline eGFR and ACR completely attenuated the association between family history of ESRD and incident ESRD (HR, 1.12; 95% CI, 0.69-1.80).

LIMITATIONS

The report of a family history of ESRD was not validated.

CONCLUSION

Family history of ESRD is common in older Americans and the increased risk of ESRD associated with a family history reflects lower GFR, higher albuminuria, and comorbid conditions.

Microalbuminuria: causes and implications

Management strategies are increasingly focused on tackling the increasing burden of cardiovascular disease worldwide. Microalbuminuria is a powerful predictor of cardiovascular disease and mortality in adults. This holds true in the general adult population but is particularly recognized in those with diabetes, where it identifies those likely to develop progressive atherosclerotic vascular disease and renal impairment. The atherosclerotic process begins in childhood with likely consequences in later life. In-depth understanding of the mechanisms through which microalbuminuria occurs holds promise for designing therapies to arrest its development in the future. Microalbuminuria arises from increased leakage of albumin through the complex glomerular sieve known as the glomerular filtration barrier. This requires changes in the physio-chemical properties of components of this barrier. However, the increased glomerular permeability confirmed in disease does not necessarily correlate with recognized histological changes in the glomerulus, suggesting that perhaps more subtle ultrastructural changes may be relevant. The epidemiology of microalbuminuria reveals a close association between systemic endothelial dysfunction and vascular disease, also implicating glomerular endothelial dysfunction in microalbuminuria. This review discusses the mechanisms of microalbuminuria in disease, particularly the emerging role of the glomerular endothelium and its glycocalyx, and examines its implications for cardiovascular disease in the pediatric population.

Association of dietary sodium and potassium intakes with albuminuria in normal-weight, overweight, and obese participants in the Reasons for Geographic and Racial Differences in Stroke (REGARDS) Study

BACKGROUND

Among obese adults, sodium intake has been associated with cardiovascular disease. Few data are available on sodium intake and albuminuria, a marker of kidney damage and risk factor for cardiovascular disease.

OBJECTIVE

We examined the relation between dietary sodium and potassium intakes and the ratio of sodium to potassium (Na/K) with albuminuria by BMI in the Reasons for Geographic and Racial Differences in Stroke (REGARDS) Study (n = 30,239 adults aged ≥45 y).

DESIGN

A modified Block 98 food-frequency questionnaire was used for dietary assessment in 21,636 participants, and nutritional variables were categorized by sex-specific quintiles. Normal weight, overweight, and obese were defined as BMI (in kg/m(2)) categories of 18.5-24.9, 25-29.9, and ≥30, respectively. Albuminuria was defined as a ratio (mg/g) of urinary albumin to creatinine of ≥30.

RESULTS

The prevalences of albuminuria were 11.5%, 11.6%, and 16.0% in normal-weight, overweight, and obese participants, respectively. The multivariable-adjusted ORs for albuminuria in a comparison of the highest with the lowest quintile of Na/K intake (≥1.12 to <0.70 for men and ≥1.07 to <0.62 for women) were 0.89 (95% CI: 0.65, 1.22), 1.08 (95% CI: 0.85, 1.36), and 1.28 (95% CI: 1.02, 1.61) in normal-weight, overweight, and obese participants, respectively. The highest quintile of dietary sodium was associated with an increased OR for albuminuria in obese participants (OR: 1.44; 95% CI: 1.00, 2.07) but not in normal-weight or overweight participants. Dietary potassium was not associated with albuminuria.

CONCLUSION

In obese adults, higher dietary Na/K and sodium intakes were associated with albuminuria.

Progression of CKD in Hispanics: potential roles of health literacy, acculturation, and social support

Hispanics are the fastest growing minority group in the United States, and compared with non-Hispanic whites, they have a higher incidence of end-stage renal disease. Examining novel factors that may explain this disparity in progression of chronic kidney disease (CKD) in Hispanics is urgently needed. Interpersonal and patient-centered characteristics, including health literacy, acculturation, and social support, have been shown to affect health outcomes in patients with other chronic diseases. However, these characteristics have not been well studied in the context of CKD, particularly in relation to disease knowledge, attitudes, and behaviors. In this report, we examine the potential roles of these factors for CKD progression in Hispanics and propose targeted therapeutic interventions.

Relationship between microalbuminuria and vulnerable plaque components in patients with acute coronary syndrome and with diabetes mellitus. Virtual histology-intravascular ultrasound

BACKGROUND

The purpose of the present study was to use virtual histology-intravascular ultrasound (VH-IVUS) to evaluate the relationship between microalbuminuria and plaque components in 920 patients.

METHODS AND RESULTS

Patients with albumin levels <30mg/g creatinine were defined as having normoalbuminuria (n=824), and those with albumin levels 30-300mg/g as having microalbuminuria (n=96). The microalbuminuria group contained more patients with acute coronary syndrome (ACS; 72% vs. 61%, P=0.018) and more patients with diabetes (53% vs. 26%, P<0.001). In ACS patients, %necrotic core (NC) volume was significantly greater in the microalbuminuria group compared with the normoalbuminuria group (19±10% vs. 15±9%, P=0.019), but not in patients with stable angina. In ACS patients, thin-cap fibroatheroma (TCFA) was observed more frequently in the microalbuminuria group (36% vs. 18%, P=0.008), and microalbuminuria was the independent predictor of TCFA (odds ratio [OR], 1.106; 95% confidence interval [CI]: 1.025-1.144, P=0.018). In diabetic patients, %NC volume was significantly greater in the microalbuminuria group compared with the normoalbuminuria group (20±9% vs. 16±10%, P=0.017), but not in non-diabetic patients. In diabetic patients, TCFA was observed more frequently in the microalbuminuria group (38% vs. 17%, P=0.002) and microalbuminuria was the independent predictor of TCFA (OR, 1.120; 95%CI: 1.038-1.204, P=0.012).

CONCLUSIONS

Microalbuminuria was associated with a higher number of vulnerable plaque components in ACS and diabetic patients. More intensive medical therapy is needed to stabilize the vulnerable plaque if microalbuminuria is observed in diabetic ACS patients.

Increased prevalence of albuminuria in HIV-infected adults with diabetes

Objective

HIV and type 2 diabetes are known risk factors for albuminuria, but no previous reports have characterized albuminuria in HIV-infected patients with diabetes.

Research Design and Methods

We performed a cross-sectional study including 73 HIV-infected adults with type 2 diabetes, 82 HIV-infected non-diabetics, and 61 diabetic control subjects without HIV. Serum creatinine >1.5 mg/dL was exclusionary. Albuminuria was defined as urinary albumin/creatinine ratio >30 mg/g.

Results

The prevalence of albuminuria was significantly increased among HIV-infected diabetics (34% vs. 13% of HIV non-diabetic vs. 16% diabetic control, p = 0.005). HIV status and diabetes remained significant predictors of albuminuria after adjusting for age, race, BMI, and blood pressure. Albumin/creatinine ratio correlated significantly with HIV viral load (r = 0.28, p = 0.0005) and HIV-infected subjects with albuminuria had significantly greater cumulative exposure to abacavir (p = 0.01). In an adjusted multivariate regression analysis of HIV-infected subjects, the diagnosis of diabetes (p = 0.003), higher HIV viral load (p = 0.03) and cumulative exposure to abacavir (p = 0.0009) were significant independent predictors of albuminuria.

Conclusions

HIV and diabetes appear to have additive effects on albuminuria which is also independently associated with increased exposure to abacavir and HIV viral load. Future research on the persistence, progression and management of albuminuria in this unique at-risk population is needed.

Microalbuminuria in the paediatric age: current knowledge and emerging questions

The prevalence of microalbuminuria (MA) in children and adolescents differs from the one in adults, and it is estimated to be about 5.7-7.3% in boys and 12.7-15.1% in girls. The percentage is greater in smaller age group, whereas a positive association is found between albumin excretion rate and pubertal development stage in nondiabetic subjects. The data so far suggest that impairment of glucose metabolism, obesity-related proatherosclerotic pathways and the impact of haemodynamic load constitute major determinants of albuminuria development in the early years of life. In everyday practice if persistent MA is present at a young age, especially in the setting of diabetes, further investigation of cardiovascular risk factors, a more careful follow-up and dietary/lifestyle interventions are needed.

CONCLUSION

Although the significance of MA in paediatric essential hypertension has yet to be determined, its role in diabetic children and adolescents is established and albuminuria assessment has been utilized as a screening test for the presence of diabetes-related kidney disease.

Uncontrolled and apparent treatment resistant hypertension in the United States, 1988 to 2008

BACKGROUND

Despite progress, many hypertensive patients remain uncontrolled. Defining characteristics of uncontrolled hypertensives may facilitate efforts to improve blood pressure control.

METHODS AND RESULTS

Subjects included 13,375 hypertensive adults from National Health and Nutrition Examination Surveys (NHANESs) subdivided into 1988 to 1994, 1999 to 2004, and 2005 to 2008. Uncontrolled hypertension was defined as blood pressure ≥140/≥90 mm Hg and apparent treatment-resistant hypertension (aTRH) when subjects reported taking ≥3 antihypertensive medications. Framingham 10-year coronary risk was calculated. Multivariable logistic regression was used to identify clinical characteristics associated with untreated, treated uncontrolled on 1 to 2 blood pressure medications, and aTRH across all 3 survey periods. More than half of uncontrolled hypertensives were untreated across surveys, including 52.2% in 2005 to 2008. Clinical factors linked with untreated hypertension included male sex, infrequent healthcare visits (0 to 1 per year), body mass index <25 kg/m2, absence of chronic kidney disease, and Framingham 10-year coronary risk <10% (P<0.01). Most treated uncontrolled patients reported taking 1 to 2 blood pressure medications, a proxy for therapeutic inertia. This group was older, had higher Framingham 10-year coronary risk than patients controlled on 1 to 2 medications (P<0.01), and comprised 34.4% of all uncontrolled and 72.0% of treated uncontrolled patients in 2005 to 2008. We found that aTRH increased from 15.9% (1998-2004) to 28.0% (2005-2008) of treated patients (P<0.001). Clinical characteristics associated with aTRH included ≥4 visits per year, obesity, chronic kidney disease, and Framingham 10-year coronary risk >20% (P<0.01).

CONCLUSION

Untreated, undertreated, and aTRH patients have consistent characteristics that could inform strategies to improve blood pressure control by decreasing untreated hypertension, reducing therapeutic inertia in undertreated patients, and enhancing therapeutic efficiency in aTRH.

CKD in Hispanics: Baseline characteristics from the CRIC (Chronic Renal Insufficiency Cohort) and Hispanic-CRIC Studies

BACKGROUND

Little is known regarding chronic kidney disease (CKD) in Hispanics. We compared baseline characteristics of Hispanic participants in the Chronic Renal Insufficiency Cohort (CRIC) and Hispanic-CRIC (H-CRIC) Studies with non-Hispanic CRIC participants.

STUDY DESIGN

Cross-sectional analysis.

SETTING & PARTICIPANTS

Participants were aged 21-74 years with CKD using age-based estimated glomerular filtration rate (eGFR) at enrollment into the CRIC/H-CRIC Studies. H-CRIC included Hispanics recruited at the University of Illinois in 2005-2008, whereas CRIC included Hispanics and non-Hispanics recruited at 7 clinical centers in 2003-2007.

FACTOR

Race/ethnicity.

OUTCOMES

Blood pressure, angiotensin-converting enzyme (ACE)-inhibitor/angiotensin receptor blocker (ARB) use, and CKD-associated complications.

MEASUREMENTS

Demographic characteristics, laboratory data, blood pressure, and medications were assessed using standard techniques and protocols.

RESULTS

Of H-CRIC/CRIC participants, 497 were Hispanic, 1,650 were non-Hispanic black, and 1,638 were non-Hispanic white. Low income and educational attainment were nearly twice as prevalent in Hispanics compared with non-Hispanics (P < 0.01). Hispanics had self-reported diabetes (67%) more frequently than non-Hispanic blacks (51%) and whites (40%; P < 0.01). Blood pressure >130/80 mm Hg was more common in Hispanics (62%) than blacks (57%) and whites (35%; P < 0.05), and abnormalities in hematologic, metabolic, and bone metabolism parameters were more prevalent in Hispanics (P < 0.05), even after stratifying by entry eGFR. Hispanics had the lowest use of ACE inhibitors/ARBs among the high-risk subgroups, including participants with diabetes, proteinuria, and blood pressure >130/80 mm Hg. Mean eGFR was lower in Hispanics (39.6 mL/min/1.73 m(2)) than in blacks (43.7 mL/min/1.73 m(2)) and whites (46.2 mL/min/1.73 m(2)), whereas median proteinuria was higher in Hispanics (protein excretion, 0.72 g/d) than in blacks (0.24 g/d) and whites (0.12 g/d; P < 0.01).

LIMITATIONS

Generalizability; observed associations limited by residual bias and confounding.

CONCLUSIONS

Hispanics with CKD in the CRIC/H-CRIC Studies are disproportionately burdened with lower socioeconomic status, more frequent diabetes mellitus, less ACE-inhibitor/ARB use, worse blood pressure control, and more severe CKD and associated complications than their non-Hispanic counterparts.

Kidney function reference values in US adolescents: National Health And Nutrition Examination Survey 1999-2008

BACKGROUND AND OBJECTIVES

Few data are available on kidney function in normal US adolescents. This study characterizes the distribution of kidney function measures and associated factors.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Serum creatinine, cystatin C, and urinary albumin-to-creatinine ratios were measured in US adolescents (aged 12 to 17 years; n = 5575) in the cross-sectional National Health and Nutrition Examination Survey 1999-2008. The reference population was defined as healthy adolescents with BP <120/80 mmHg and a Z-score for weight-to-height ≤1.645, without self-reported diabetes or hypertension, not using prescription medications in the preceding 30 days, not pregnant or currently menstruating.

RESULTS

were analyzed by age, gender, race, ethnicity, body mass index, and BP; estimated GFR (eGFR) was calculated using the original and revised Schwartz formulas. Results Mean values for eGFR(Schwartz original formula), serum creatinine, and serum cystatin C were 147 ml/min/1.73 m(2), 0.71 mg/dl, 0.82 mg/L, respectively. The median urinary albumin-to-creatinine ratio was 6.8 mg/g creatinine. In the reference population (n = 2881), eGFR differed significantly using the two Schwartz formulas; values were higher using the original formula (median values 143 versus 96 ml/min/1.73 m(2)). Serum creatinine level (0.7 versus 0.72 mg/dl), but not cystatin C level (0.82 versus 0.82 mg/L), was lower in the reference population than in a nonreference population of adolescents.

CONCLUSIONS

These findings provide important demographic information and highlight the need for confirmatory testing of the revised Schwartz formula by comparison to measured GFR in healthy US adolescents.

Microalbuminuria: A novel biomarker of sepsis

CONTEXT

Diffused endothelial dysfunction in sepsis leads to an increase in systemic capillary permeability, the renal component manifesting as microalbuminuria. The degree of microalbuminuria correlates with the severity of the acute insult, the quantification of which may serve to predict sepsis and mortality in critically ill patients.

AIMS

To evaluate whether the degree of microalbuminuria could differentiate patients with sepsis from those without and predict mortality in critically ill patients.

SETTINGS AND DESIGN

Prospective, non-interventional study in a 20-bed Intensive Care Unit (ICU) of a tertiary care hospital.

METHODS AND MATERIALS

After exclusions, between Jan-May 2007, 94 consecutive adult patients were found eligible. Albumin-creatinine ratio (ACR, mg/g) was measured in urine samples collected on ICU admission (ACR1) and at 24 hours (ACR2).

RESULTS

PATIENTS WERE CLASSIFIED INTO TWO GROUPS: those with sepsis, severe sepsis and septic shock (n = 30) and those without sepsis [patients without systemic inflammatory response syndrome (SIRS) and with SIRS due to noninfectious causes] (n = 64). In the sepsis group, median ACR1 [206.5 (IQR129.7-506.1)] was significantly higher compared to the non sepsis group [76.4 (IQR29-167.1)] (P = 0.0016, Mann Whitney). The receiver operating characteristics (ROC) curve analysis showed that at a cut off value 124 mg/g, ACR1 may be able to discriminate between patients with and without sepsis with a sensitivity of 80%, specificity of 64.1%, positive predictive value (PPV) of 51.1% and negative predictive value (NPV) of 87.3%. The median ACR2 [154 (IQR114.4-395.3)] was significantly higher (P = 0.004) in nonsurvivors (n = 13) as compared to survivors [50.8 (IQR 21.6-144.7)]. The ROC curve analysis revealed that ACR2 at a cut-off of 99.6 mg/g could predict ICU mortality with sensitivity of 85%, specificity of 68% with a NPV of 97% and PPV of 30%.

CONCLUSION

Absence of significant microalbuminuria on ICU admission is unlikely to be associated with sepsis. At 24 hours, absence of elevated levels of microalbuminuria is strongly predictive of ICU survival, equivalent to the time-tested APACHE II scores.

Chronic kidney disease of unknown aetiology in Sri Lanka: is cadmium a likely cause?

Background

The rising prevalence of chronic kidney disease (CKD) and subsequent end stage renal failure necessitating renal replacement therapy has profound consequences for affected individuals and health care resources. This community based study was conducted to identify potential predictors of microalbuminuria in a randomly selected sample of adults from the North Central Province (NCP) of Sri Lanka, where the burden of CKD is pronounced and the underlying cause still unknown.

Methods

Exposures to possible risk factors were determined in randomly recruited subjects (425 females and 461 males) from selected areas of the NCP of Sri Lanka using an interviewer administered questionnaire. Sulphosalicylic acid and the Light Dependent Resister microalbumin gel filtration method was used for initial screening for microalbuminuria and reconfirmed by the Micral strip test.

Results

Microalbumnuria was detected in 6.1% of the females and 8.5% of the males. Smoking (p < 0.001), alcohol use (p = 0.003), hypertension (p < 0.001), diabetes (p < 0.001), urinary tract infection (UTI) (p = 0.034) and consumption of water from wells in the fields (p = 0.025) were associated with microalbuminuria. In the binary logistic regression analysis, hypertension, diabetes mellitus, UTI, drinking well water in the fields, smoking and pesticide spraying were found to be significant predictors of microalbuminuria.

Conclusions

Hypertension, diabetes mellitus, UTI, and smoking are known risk factors for microalbuminuria. The association between microalbuminuria and consumption of well water suggests an environmental aetiology to CKD in NCP. The causative agent is yet to be identified. Investigations for cadmium as a potential causative agent needs to be initiated.

Chronic kidney disease of unknown aetiology in Sri Lanka: is cadmium a likely cause?

BACKGROUND

The rising prevalence of chronic kidney disease (CKD) and subsequent end stage renal failure necessitating renal replacement therapy has profound consequences for affected individuals and health care resources. This community based study was conducted to identify potential predictors of microalbuminuria in a randomly selected sample of adults from the North Central Province (NCP) of Sri Lanka, where the burden of CKD is pronounced and the underlying cause still unknown.

METHODS

Exposures to possible risk factors were determined in randomly recruited subjects (425 females and 461 males) from selected areas of the NCP of Sri Lanka using an interviewer administered questionnaire. Sulphosalicylic acid and the Light Dependent Resister microalbumin gel filtration method was used for initial screening for microalbuminuria and reconfirmed by the Micral strip test.

RESULTS

Microalbumnuria was detected in 6.1% of the females and 8.5% of the males. Smoking (p < 0.001), alcohol use (p = 0.003), hypertension (p < 0.001), diabetes (p < 0.001), urinary tract infection (UTI) (p = 0.034) and consumption of water from wells in the fields (p = 0.025) were associated with microalbuminuria. In the binary logistic regression analysis, hypertension, diabetes mellitus, UTI, drinking well water in the fields, smoking and pesticide spraying were found to be significant predictors of microalbuminuria.

CONCLUSIONS

Hypertension, diabetes mellitus, UTI, and smoking are known risk factors for microalbuminuria. The association between microalbuminuria and consumption of well water suggests an environmental aetiology to CKD in NCP. The causative agent is yet to be identified. Investigations for cadmium as a potential causative agent needs to be initiated.

Microalbuminuria in normal Korean children

PURPOSE

Although microalbuminuria is known as a predictor of clinical nephropathy and cardiomyopathy, few studies have investigated the incidence and reference range of microalbuminuria in healthy children. This study aimed to establish a reference range and to study the age-related trend for spot urine microalbumin/creatinine ratio in a Korean pediatric population.

MATERIALS AND METHODS

352 healthy children were studied from July 2007 through March 2010. Height, weight, serum creatinine, spot urine microalbumin/creatinine ratio, and glomerular filtration rate (GFR) were obtained for each subject. We divided the study population into 5 groups according to age, and compared the spot urine microalbumin/creatinine ratio with other variables using one-way analysis of variance (ANOVA), regression analysis and Pearson's correlation analysis.

RESULTS

In this study, the data showed that the spot urine microalbumin/creatinine ratio decreased with age: 1-12 months, 22.72 ± 13.80 mg/mmol (2SD: 3.33-54.40 mg/mmol); 13-28 months, 16.34 ± 9.58 mg/mmol (2SD: 3.16-35.19 mg/mmol); 29-48 months, 13.12 ± 9.74 mg/mmol (2SD: 3.01-41.57 mg/mmol); 4-6 years, 10.58 ± 8.13 mg/mmol (2SD: 0.00-30.19 mg/mmol); and 7-19 years, 5.13±5.44 mg/mmol (2SD: 0.45-14.45 mg/mmol). The spot urine microalbumin/creatinine ratio showed correlation with age, height, height z-score, weight, weight z-score, GFR, body mass index (BMI) and body surface area (BSA).

CONCLUSION

The spot urine microalbumin/creatinine ratio in normal Korean children decreased with age. This ratio could potentially be used to establish reference ranges and cutoff values for Korean children and to predict nephropathy and cardiomyopathy.

Long-term indapamide retard therapy in adolescents with Stage I arterial hypertension

Aim. To study the dynamics of office blood pressure (BP) levels, autonomic balance, endothelial dysfunction, and vascular remodelling in adolescents with Stage I arterial hypertension (AH), treated with indapamide retard (IR). Material and methods. In total, the study included 41 adolescent boys, aged 16-18 years, with Stage I AH (main group, MG), and 27 healthy adolescents (control group, CG). The MG participants received, IR (1,5 mg/day) for 6 months. At baseline and in the end of the study, all participants underwent office BP measurement, echocardiography, veloergometry, and the assessment of heart rate variability (HRV), endothelial dysfunction (reactive hyperemia test, endotelin-1 levels), microalbuminuria (MAU), and vascular parameters, such as large artery rigidity and intima-media thickness. Results. Target BP levels were achieved in all MG patients by Week 4 of the treatment, with normal BP values registered throughout the follow-up period. Indapamide therapy was associated with decreased hemodynamic cardiovascular load, normalized endothelial function, and MAU disappearance. IR monotherapy had beneficial effects on HRV, due to moderate parasympathetic stimulation. Conclusion. IR is an effective and safe medication for long-term treatment of adolescents with Stage I AH.

Effects of race on albuminuria and risk of cardiovascular and kidney disease

The literature describing the relationship between urinary protein excretion and risk of cardiovascular disease and renal disease is rapidly proliferating. Several studies have demonstrated racial differences in the relationship between albuminuria and associated disorders. The purpose of this article is to summarize the effects of race on the relationship between albuminuria and renal and cardiovascular disease risk, propose explanatory hypotheses, and suggest directions for future investigation.

Increased circulating CD31+/annexin V+ apoptotic microparticles and decreased circulating endothelial progenitor cell levels in hypertensive patients with microalbuminuria

OBJECTIVE

Microalbuminuria is associated with an increased risk for all-cause and cardiovascular mortality, but the pathophysiologic mechanism underlying the association between urinary albumin excretion and cardiovascular disease remains unclear. Here, we tested the hypothesis that enhanced endothelial apoptotic microparticles and decreased endothelial progenitor cell (EPC) levels might contribute to the pathophysiology of microalbuminuria or macroalbuminuria in cardiovascular disease.

METHODS

Flow cytometry was used to assess endothelial cell apoptosis and circulating EPC levels by quantification of circulating CD31/annexin V apoptotic microparticles and EPC markers (defined as KDRCD133, CD34CD133, CD34KDR) in peripheral blood.

RESULTS

In total, 125 patients with hypertension were enrolled in the study, of whom 80 patients (64%) were with normoalbuminuria (albumin excretion rate of <20 microg/min, overnight urine samples), 35 patients (28%) with microalbuminuria (an albumin excretion rate of 20-200 microg/min), and 10 patients (8%) with macroalbuminuria (an albumin excretion rate >200 microg/min). Compared to hypertensive patients with normoalbuminuria, patients with microalbuminuria or macroalbuminuria had significantly more diabetes (P = 0.005), higher systolic blood pressure (P = 0.018), and elevated serum creatinine levels (P < 0.001). Among the three groups, patients with microalbuminuria or macroalbuminuria had significantly increased CD31/annexin V apoptotic microparticles (1.8 +/- 2.2 versus 3.0 +/- 4.3 versus 5.2 +/- 6.2%, P = 0.044) and decreased circulating EPC numbers (P < 0.05). By multivariate analysis, CD31/annexin V apoptotic microparticle level was an independent predictor of urinary albumin excretion rate in hypertensive patients (P < 0.001). Microparticles isolated from hypertensive patients with microalbuminuria or macroalbuminuria attenuated EPC proliferation, migration, and increased H2O2 production, cellular senescence and apoptosis in comparison with those from hypertensive patients with normoalbuminuria.

CONCLUSION

These findings suggest that hypertensive patients with microalbuminuria or macroalbuminuria have increased endothelial apoptotic microparticles and decreased circulating EPC levels, which may contribute to atherosclerotic disease progression and enhanced cardiovascular risk in hypertensive patients with nephropathy.

Inflammation gene variants and susceptibility to albuminuria in the U.S. population: analysis in the Third National Health and Nutrition Examination Survey (NHANES III), 1991-1994

BACKGROUND

Albuminuria, a common marker of kidney damage, serves as an important predictive factor for the progression of kidney disease and for the development of cardiovascular disease. While the underlying etiology is unclear, chronic, low-grade inflammation is a suspected key factor. Genetic variants within genes involved in inflammatory processes may, therefore, contribute to the development of albuminuria.

METHODS

We evaluated 60 polymorphisms within 27 inflammatory response genes in participants from the second phase (1991-1994) of the Third National Health and Nutrition Examination Survey (NHANES III), a population-based and nationally representative survey of the United States. Albuminuria was evaluated as logarithm-transformed albumin-to-creatinine ratio (ACR), as ACR ≥ 30 mg/g, and as ACR above sex-specific thresholds. Multivariable linear regression and haplotype trend analyses were conducted to test for genetic associations in 5321 participants aged 20 years or older. Differences in allele and genotype distributions among non-Hispanic whites, non-Hispanic blacks, and Mexican Americans were tested in additive and codominant genetic models.

RESULTS

Variants in several genes were found to be marginally associated (uncorrected P value < 0.05) with log(ACR) in at least one race/ethnic group, but none remained significant in crude or fully-adjusted models when correcting for the false-discovery rate (FDR). In analyses of sex-specific albuminuria, IL1B (rs1143623) among Mexican Americans remained significantly associated with increased odds, while IL1B (rs1143623), CRP (rs1800947) and NOS3 (rs2070744) were significantly associated with ACR ≥ 30 mg/g in this population (additive models, FDR-P < 0.05). In contrast, no variants were found to be associated with albuminuria among non-Hispanic blacks after adjustment for multiple testing. The only variant among non-Hispanic whites significantly associated with any outcome was TNF rs1800750, which failed the test for Hardy-Weinberg proportions in this population. Haplotypes within MBL2, CRP, ADRB2, IL4R, NOS3, and VDR were significantly associated (FDR-P < 0.05) with log(ACR) or albuminuria in at least one race/ethnic group.

CONCLUSIONS

Our findings suggest a small role for genetic variation within inflammation-related genes to the susceptibility to albuminuria. Additional studies are needed to further assess whether genetic variation in these, and untested, inflammation genes alter the susceptibility to kidney damage.

A population-based survey of Chronic REnal Disease In Turkey--the CREDIT study

Background. Chronic kidney disease (CKD) is a growing health problem worldwide that leads to end-stage kidney failure and cardiovascular complications. We aimed to determine the prevalence of CKD in Turkey, and to evaluate relationships between CKD and cardiovascular risk factors in a population-based survey.

Methods. Medical data were collected through home visits and interviews. Serum creatinine, blood glucose, total cholesterol, triglycerides, HDL, LDL and uric acid were determined from 12-h fasting blood samples, and spot urine tests were performed for subjects who gave consent to laboratory evaluation.

Results. A total of 10 872 participants were included in the study. The final analysis was performed on 10 748 subjects (mean age 40.5 ± 16.3 years; 55.7% women) and excluded 124 pregnant women. A low glomerular filtration rate (GFR) (< 60 mL/min/1.73 m²) was present in 5.2% of the subjects who were evaluated for GFR, while microalbuminuria and macroalbuminuria were observed in 10.2% and 2% of the subjects, respectively. The presence of CKD was assessed in subjects who gave consent for urinary albumin excretion measurement (n = 8765). The overall prevalence of CKD was 15.7%; it was higher in women than men (18.4% vs. 12.8%, P < 0.001) and increased with increasing age of the subjects. The prevalence of hypertension (32.7% in the general population), diabetes (12.7%), dyslipidaemia (76.3%), obesity (20.1%) and metabolic syndrome (31.3%) was significantly higher in subjects with CKD than subjects without CKD (P < 0.001 for all).

Conclusions. The prevalence of CKD in Turkey is 15.7%. Cardiovascular risk factors were significantly more prevalent in CKD patients.

Relationship between body mass index and proteinuria in hypertensive nephrosclerosis: results from the African American Study of Kidney Disease and Hypertension (AASK) cohort

BACKGROUND

Few studies have examined the association between obesity and markers of kidney injury in a chronic kidney disease population. We hypothesized that obesity is independently associated with proteinuria, a marker of chronic kidney disease progression.

STUDY DESIGN

Observational cross-sectional analysis.

SETTING & PARTICIPANTS

Post hoc analysis of baseline data for 652 participants in the African American Study of Kidney Disease (AASK).

PREDICTORS

Obesity, determined using body mass index (BMI).

MEASUREMENTS & OUTCOMES

Urine total protein-creatinine ratio and albumin-creatinine ratio measured in 24-hour urine collections.

RESULTS

AASK participants had a mean age of 60.2 ± 10.2 years and serum creatinine level of 2.3 ± 1.5 mg/dL; 61.3% were men. Mean BMI was 31.4 ± 7.0 kg/m(2). Approximately 70% of participants had a daily urine total protein excretion rate <300 mg/d. In linear regression analyses adjusted for sex, each 2-kg/m(2) increase in BMI was associated with a 6.7% (95% CI, 3.2-10.4) and 9.4% (95% CI, 4.9-14.1) increase in urine total protein-creatinine and urine albumin-creatinine ratios, respectively. In multivariable models adjusting for age, sex, systolic blood pressure, serum glucose level, uric acid level, and creatinine level, each 2-kg/m(2) increase in BMI was associated with a 3.5% (95% CI, 0.4-6.7) and 5.6% (95% CI, 1.5-9.9) increase in proteinuria and albuminuria, respectively. The interaction between older age and BMI was statistically significant, indicating that this relationship was driven by younger AASK participants.

LIMITATIONS

May not generalize to other populations; cross-sectional analysis precludes statements regarding causality.

CONCLUSIONS

BMI is associated independently with urine total protein and albumin excretion in African Americans with hypertensive nephrosclerosis, particularly in younger patients.