Microalbuminuria in nondiabetic patients with nonalcoholic fatty liver disease: association with liver fibrosis

Nonalcoholic fatty liver disease is associated with low-grade albuminuria in Chinese adults (change not displayed)

BACKGROUND

Nonalcoholic fatty liver disease (NAFLD) was associated with higher risk of cardiovascular disease (CVD). Low-grade albuminuria was recognized as an early indicator of CVD. Epidemiological studies investigating the association between NAFLD and low-grade albuminuria were limited.

AIM

To determine whether NAFLD is independently associated with the presence of low-grade albuminuria in Chinese adults.

DESIGN

A cross-sectional community-based population study was performed in 8270 Chinese adults aged 40 years or older.

METHODS

A first-voided early morning spot urine sample was obtained for urinary albumin and creatinine measurements. The highest quartile of urinary albumin-to-creatinine ratio was defined as low-grade albuminuria, after excluding the participants with micro- or macroalbuminuria. NAFLD was diagnosed by using ultrasonography findings after the exclusion of alcohol abuse and other liver diseases.

RESULTS

The prevalence of low-grade albuminuria was significantly higher in participants with NAFLD than in those without NAFLD (33.6% vs. 21.3% in men and 30.4% vs. 22.8% in women, respectively). Multivariate-adjusted logistic regression analysis revealed that NAFLD was significantly associated with increased odds ratio of low-grade albuminuria in men (odds ratio, 1.47; 95% CI, 1.16-1.87) after adjusting for multiple confounders. The significant association was not detected in women.

CONCLUSIONS

NAFLD was significantly associated with an increased risk of present low-grade albuminuria in middle-aged and elderly Chinese men.

Extrahepatic Complications of Nonalcoholic Fatty Liver Disease

Nonalcoholic fatty liver disease (NAFLD) is an important cause of liver disease that is often associated with the metabolic syndrome. There is a growing awareness that extrahepatic complications occur in individuals with NAFLD, especially an increased risk of cardiovascular disease. Development of diabetes mellitus, chronic kidney disease, colorectal cancer, and endocrinopathies has been linked to NAFLD. This article reviews the extrahepatic complications affecting individuals with NAFLD and the pathogenesis underlying their development.

NAFLD and Chronic Kidney Disease

Non-alcoholic fatty liver disease (NAFLD) is the most common cause of chronic liver disease in developed countries and it is now considered a risk factor for cardiovascular disease. Evidence linking NAFLD to the development and progression of chronic kidney disease (CKD) is emerging as a popular area of scientific interest. The rise in simultaneous liver-kidney transplantation as well as the significant cost associated with the presence of chronic kidney disease in the NAFLD population make this entity a worthwhile target for screening and therapeutic intervention. While several cross-sectional and case control studies have been published to substantiate these theories, very little data exists on the underlying cause of NAFLD and CKD. In this review, we will discuss the most recent publications on the diagnosis of NAFLD as well new evidence regarding the pathophysiology of NAFLD and CKD as an inflammatory disorder. These mechanisms include the role of obesity, the renin-angiotensin system, and dysregulation of fructose metabolism and lipogenesis in the development of both disorders. Further investigation of these pathways may lead to novel therapies that aim to target the NAFLD and CKD. However, more prospective studies that include information on both renal and liver histology will be necessary in order to understand the relationship between these diseases.

Nonalcoholic fatty liver is not associated with incident chronic kidney disease: a large histology-based comparison with healthy individuals

BACKGROUND

Nonalcoholic steatohepatitis or fibrosis is associated with the increased prevalence of impaired kidney function. It is not known whether nonalcoholic fatty liver (NAFL), which is steatosis without inflammation or fibrosis, is associated with renal impairment as these individuals are not candidates for liver biopsy.

MATERIALS AND METHODS

The study group included all liver donors who underwent a preoperative liver biopsy for various reasons. NAFL was defined as more than 5% hepatocytes having steatosis and no changes of steatohepatitis and/or fibrosis. Individuals with NAFL were compared with individuals with normal liver histology. Estimated glomerular filtration rate was calculated with the Modification of Diet in Renal Disease and Chronic Kidney Disease Epidemiology Collaboration methods.

RESULTS

The mean age of the study group was 35±10.3 years and the mean BMI was 26±3.2 kg/m. A total of 187 adults having NAFL (80 men) were compared with 186 (88 men) individuals with normal liver histology (controls). Individuals with steatosis had significantly higher BMI (26.8±3.5 vs. 25.5±3.8 kg/m, P<0.001) and serum alanine transaminase levels (33.8±13.3 vs. 27.2±9.8 IU/l, P<0.000). There was no significant difference in the estimated glomerular filtration rate between the normal histology group and the NAFL group with Modification of Diet in Renal Disease (115±21.8 vs. 114.4±23.2 ml/min, P=0.803) and Chronic Kidney Disease Epidemiology Collaboration methods (113.6±14.8 vs. 113±14.7 ml/min, P=0.668). There was no significant difference as regards serum creatinine (0.73±0.16 vs. 0.74±0.16 mg%, P=0.536), proteinuria (P=0.121), diabetes (1 vs. 4, P=0.372), and hypertension (2 vs. 6, P=0.174) in individuals of both groups.

CONCLUSION

Presence of NAFL does not adversely affect renal function.

Nonalcoholic Fatty Liver Disease (NAFLD)-A New Cardiovascular Risk Factor in Peritoneal Dialysis Patients

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BACKGROUND

Recent investigations indicated that nonalcoholic fatty liver disease (NAFLD), a hepatic component of metabolic syndrome (MS), is associated with an increased risk of cardiovascular disease (CVD). Accordingly, we were interested in exploring the frequency of NAFLD in peritoneal dialysis (PD) patients and analyzing factors in PD patients associated with NAFLD occurrence. In addition, we were interested in investigating whether NAFLD is associated with higher CVD risk in our PD patients. ♦

METHODS

In the present cross-sectional study, we analyzed 58 PD patients. The controlled attenuation parameter (CAP) was used to detect and quantify liver steatosis with the help of transient elastography (TE) (FibroScan, Echosense SA, Paris, France). A carotid ultrasound was performed in all patients to measure carotid intimae media thickness (IMT) and plaque as surrogate measures of increased CVD risk, and we investigated their association with NAFLD. ♦

RESULTS

Nonalcoholic fatty liver disease was present in 74.1% of PD patients. Peritoneal dialysis/nonalcoholic fatty liver disease patients had statistically greater daily (136.5 ± 62.6 vs 93.6 ± 36.1; p = 0.02) and monthly (4,095.3 ± 1,877.7 vs 2,806.6 ± 1,083.2; p = 0.02) glucose load in comparison to the non-NAFLD/PD patients. In the next step, we were interested in analyzing what demographic and clinical characteristics in our PD patients are associated with a higher NAFLD occurrence. Presence of diabetes mellitus (DM), arterial hypertension (AH), dyslipidemia, body mass index > 25 kg/m(2), and daily glucose load > 100 g were associated with NAFLD occurrence. Peritoneal dialysis patients with NAFLD showed more carotid atherosclerosis than PD patients without NAFLD. In addition, CAP values (as indicator of liver steatosis) showed strong positive association with IMT (r = 0.801; p < 0.0001). Nonalcoholic fatty liver disease was a strong predictor of carotid atherosclerosis in PD patients. ♦

CONCLUSION

Nonalcoholic fatty liver disease is highly prevalent in PD patients. Peritoneal dialysis patients with NAFLD are at high risk of atherosclerosis. Assessment of NAFLD in PD patients may be helpful for CVD risk stratification.

Mechanism of Altered Metformin Distribution in Nonalcoholic Steatohepatitis

Metformin is an antihyperglycemic drug that is widely prescribed for type 2 diabetes mellitus and is currently being investigated for the treatment of nonalcoholic steatohepatitis (NASH). NASH is known to alter hepatic membrane transporter expression and drug disposition similarly in humans and rodent models of NASH. Metformin is almost exclusively eliminated through the kidney primarily through active secretion mediated by Oct1, Oct2, and Mate1. The purpose of this study was to determine how NASH affects kidney transporter expression and metformin pharmacokinetics. A single oral dose of [(14)C]metformin was administered to C57BL/6J (wild type [WT]) and diabetic ob/ob mice fed either a control diet or a methionine- and choline-deficient (MCD) diet. Metformin plasma concentrations were slightly increased in the WT/MCD and ob/control groups, whereas plasma concentrations were 4.8-fold higher in ob/MCD mice compared with WT/control. The MCD diet significantly increased plasma half-life and mean residence time and correspondingly decreased oral clearance in both genotypes. These changes in disposition were caused by ob/ob- and MCD diet-specific decreases in the kidney mRNA expression of Oct2 and Mate1, whereas Oct1 mRNA expression was only decreased in ob/MCD mice. These results indicate that the diabetic ob/ob genotype and the MCD disease model alter kidney transporter expression and alter the pharmacokinetics of metformin, potentially increasing the risk of drug toxicity.

NAFLD: a multisystem disease

Non-alcoholic fatty liver disease (NAFLD) is the most common cause of chronic liver disease in Western countries that is predicted to become also the most frequent indication for liver transplantation by 2030. Over the last decade, it has been shown that the clinical burden of NAFLD is not only confined to liver-related morbidity and mortality, but there is now growing evidence that NAFLD is a multisystem disease, affecting extra-hepatic organs and regulatory pathways. For example, NAFLD increases risk of type 2 diabetes mellitus (T2DM), cardiovascular (CVD) and cardiac diseases, and chronic kidney disease (CKD). Although the primary liver pathology in NAFLD affects hepatic structure and function to cause morbidity and mortality from cirrhosis, liver failure and hepatocellular carcinoma, the majority of deaths among NAFLD patients are attributable to CVD. This narrative review focuses on the rapidly expanding body of clinical evidence that supports the concept of NAFLD as a multisystem disease. The review discusses the factors involved in the progression of liver disease in NAFLD and the factors linking NAFLD with other extra-hepatic chronic diseases, such as T2DM, CVD, cardiac diseases and CKD. The review will not discuss NAFLD treatments as these are discussed elsewhere in this issue of the Journal. For this review, PubMed was searched for articles using the keywords "non-alcoholic fatty liver disease" or "fatty liver" combined with "diabetes", "cardiovascular (or cardiac) disease", "cardiovascular mortality" or "chronic kidney disease" between 1990 and 2014. Articles published in languages other than English were excluded.

Comorbidities and Metabolic Derangement of NAFLD

Nonalcoholic fatty liver disease (NAFLD) is an increasingly common cause of chronic liver disease worldwide and is becoming a major public health problem. NAFLD has been recognized as a hepatic manifestation of metabolic syndrome linked with insulin resistance. Growing evidence supports that NAFLD is associated with systemic diseases such as cardiovascular disease (CVD), chronic kidney disease (CKD), type 2 diabetes, obesity, and metabolic syndrome. The majority of deaths in patients with NAFLD come from cardiovascular disease. These findings are strongly attributed to nonalcoholic steatohepatitis (NASH) rather than simple steatosis. NAFLD should be considered not only a liver specific disease but also an early mediator of systemic disease. The underlying mechanisms and pathogenesis of NAFLD with regard to other medical disorders are not yet fully understood. Further investigation is needed for future therapeutic strategies for NAFLD. This review focuses on the relationship between NAFLD and various comorbid diseases and metabolic derangement.

Nonalcoholic steatohepatitis in precision medicine: Unraveling the factors that contribute to individual variability

There are numerous factors in individual variability that make the development and implementation of precision medicine a challenge in the clinic. One of the main goals of precision medicine is to identify the correct dose for each individual in order to maximize therapeutic effect and minimize the occurrence of adverse drug reactions. Many promising advances have been made in identifying and understanding how factors such as genetic polymorphisms can influence drug pharmacokinetics (PK) and contribute to variable drug response (VDR), but it is clear that there remain many unidentified variables. Underlying liver diseases such as nonalcoholic steatohepatitis (NASH) alter absorption, distribution, metabolism, and excretion (ADME) processes and must be considered in the implementation of precision medicine. There is still a profound need for clinical investigation into how NASH-associated changes in ADME mediators, such as metabolism enzymes and transporters, affect the pharmacokinetics of individual drugs known to rely on these pathways for elimination. This review summarizes the key PK factors in individual variability and VDR and highlights NASH as an essential underlying factor that must be considered as the development of precision medicine advances. A multifactorial approach to precision medicine that considers the combination of two or more risk factors (e.g. genetics and NASH) will be required in our effort to provide a new era of benefit for patients.

Liver steatosis and the risk of albuminuria: the multi-ethnic study of atherosclerosis

OBJECTIVE

To measure association between hepatic fat and albuminuria (an early marker of renal injury) in individuals without diabetes or hypertension.

METHODS

2,281 individuals in the Multi-Ethnic Study of Atherosclerosis without diabetes or hypertension, renal disease, or excess alcohol consumption underwent computed tomography (CT) for assessment of liver attenuation (marker of hepatic lipid content) and urinalysis (for albuminuria) at initial study visit, with assessment of incident and prevalent albuminuria by logistic regression in follow-up.

RESULTS

After adjustment for age, gender, race, smoking, blood pressure, insulin resistance, and body mass index, individuals with less liver fat (higher liver CT attenuation) had a lower probability of having albuminuria at Exam 1 (OR per 10 unit increase in attenuation 0.77, 95 % CI 0.61-0.97, P = 0.02). At median 9.3 years follow-up, albuminuria was identified in 129 individuals were (5.8 %). In fully adjusted models (with age, smoking, body mass index, blood pressure, diabetes and hypertension as time-dependent covariates), lower liver attenuation (greater liver fat) was associated with higher risk of incident albuminuria (OR 0.79, 95 % CI 0.66-0.94, P = 0.008).

CONCLUSIONS

Hepatic attenuation is associated with prevalent and incident albuminuria, an early, potent risk factor for renal risk in a population not clearly at risk for future renal failure.

Nonalcoholic fatty liver disease and vascular disease: State-of-the-art

Nonalcoholic fatty liver disease (NAFLD), the most common of chronic liver disease in Western Country, is closely related to insulin resistance and oxidative stress and includes a wide spectrum of liver diseases ranging from steatosis alone, usually a benign and non-progressive condition, to nonalcoholic steatohepatitis (NASH), which may progress to liver fibrosis and cirrhosis. NAFLD is considered the hepatic manifestation of the metabolic syndrome with which shares several characteristics, however recent data suggest that NAFLD is linked to increased cardiovascular risk independently of the broad spectrum of risk factors of metabolic syndrome. Accumulating evidence suggests that the clinical burden of NAFLD is not restricted to liver-related morbidity and mortality, with the majority of deaths in NAFLD patients related to cardiovascular disease and cancer and not to the progression of liver disease. Retrospective and prospective studies provide evidence of a strong association between NAFLD and subclinical manifestation of atherosclerosis (increased intima-media thickness, endothelial dysfunction, arterial stiffness, impaired left ventricular function and coronary calcification). A general agreement emerging from these studies indicates that patients with NASH are at higher risk of cardiovascular diseases than those with simple steatosis, emphasizing the role of chronic inflammation in the pathogenesis of atherosclerosis of these patients. It is very likely that the different mechanisms involved in the pathogenesis of atherosclerosis in patients with NAFLD have a different relevance in the patients according to individual genetic background. In conclusion, in the presence of NAFLD patients should undergo a complete cardiovascular evaluation to prevent future atherosclerotic complications. Specific life-style modification and aggressive pharmaceutical modification will not only reduce the progression of liver disease, but also reduce morbidity for cardiovascular disease improving overall prognosis and survival.

Non-alcoholic fatty liver disease in obese adults: clinical aspects and current management strategies

Non-alcoholic fatty liver disease (NAFLD) is the most common chronic liver disorder whose prevalence is strongly linked to the current epidemic of obesity in many western countries. The prevalence of NAFLD is two to four times higher in populations with pre-existing metabolic comorbidities than in the general population. The diagnosis of primary NAFLD involves establishing the presence of hepatic steatosis or steatohepatitis by imaging or histology, along with establishing the non-alcoholic nature of the disease process and excluding competing aetiologies for hepatic steatosis. Among the indirect serum biomarkers, the NAFLD fibrosis score can help to identify patients with NAFLD and with higher likelihood of having fibrosis or cirrhosis. A liver biopsy should be considered in NAFLD patients at increased risk for steatohepatitis/advanced fibrosis and in cases where a liver biopsy is necessary to exclude co-existing chronic liver diseases and other aetiologies for hepatic steatosis. The treatment and management recommendations for obesity-associated NAFLD are aimed towards weight reduction. The currently available interventions employed to promote weight loss and improve the metabolic responses in NAFLD include lifestyle modification, pharmacotherapy and bariatric surgery.

CKD and nonalcoholic fatty liver disease

The possible link between nonalcoholic fatty liver disease and chronic kidney disease (CKD) recently has attracted considerable scientific interest. Accumulating clinical evidence indicates that the presence and severity of nonalcoholic fatty liver disease is associated significantly with CKD (defined as decreased estimated glomerular filtration rate and/or proteinuria) and that nonalcoholic fatty liver disease predicts the development and progression of CKD, independently of traditional cardiorenal risk factors. Experimental evidence also suggests that nonalcoholic fatty liver disease itself may exacerbate systemic and hepatic insulin resistance, cause atherogenic dyslipidemia, and release a variety of proinflammatory, procoagulant, pro-oxidant, and profibrogenic mediators that play important roles in the development and progression of CKD. However, despite the growing evidence linking nonalcoholic fatty liver disease with CKD, it has not been definitively established whether a causal association exists. The clinical implication for these findings is that patients with nonalcoholic fatty liver disease may benefit from more intensive surveillance or early treatment interventions to decrease the risk of CKD. In this review, we discuss the evidence linking nonalcoholic fatty liver disease with CKD and the putative mechanisms by which nonalcoholic fatty liver disease contributes to kidney damage. We also briefly discuss current treatment options for this increasingly prevalent disease that is likely to have an important future impact on the global burden of disease.

Association of non-alcoholic fatty liver disease with chronic kidney disease: a systematic review and meta-analysis

BACKGROUND

Chronic kidney disease (CKD) is a frequent, under-recognized condition and a risk factor for renal failure and cardiovascular disease. Increasing evidence connects non-alcoholic fatty liver disease (NAFLD) to CKD. We conducted a meta-analysis to determine whether the presence and severity of NAFLD are associated with the presence and severity of CKD.

METHODS AND FINDINGS

English and non-English articles from international online databases from 1980 through January 31, 2014 were searched. Observational studies assessing NAFLD by histology, imaging, or biochemistry and defining CKD as either estimated glomerular filtration rate (eGFR) <60 ml/min/1.73 m2 or proteinuria were included. Two reviewers extracted studies independently and in duplicate. Individual participant data (IPD) were solicited from all selected studies. Studies providing IPD were combined with studies providing only aggregate data with the two-stage method. Main outcomes were pooled using random-effects models. Sensitivity and subgroup analyses were used to explore sources of heterogeneity and the effect of potential confounders. The influences of age, whole-body/abdominal obesity, homeostasis model of insulin resistance (HOMA-IR), and duration of follow-up on effect estimates were assessed by meta-regression. Thirty-three studies (63,902 participants, 16 population-based and 17 hospital-based, 20 cross-sectional, and 13 longitudinal) were included. For 20 studies (61% of included studies, 11 cross-sectional and nine longitudinal, 29,282 participants), we obtained IPD. NAFLD was associated with an increased risk of prevalent (odds ratio [OR] 2.12, 95% CI 1.69-2.66) and incident (hazard ratio [HR] 1.79, 95% CI 1.65-1.95) CKD. Non-alcoholic steatohepatitis (NASH) was associated with a higher prevalence (OR 2.53, 95% CI 1.58-4.05) and incidence (HR 2.12, 95% CI 1.42-3.17) of CKD than simple steatosis. Advanced fibrosis was associated with a higher prevalence (OR 5.20, 95% CI 3.14-8.61) and incidence (HR 3.29, 95% CI 2.30-4.71) of CKD than non-advanced fibrosis. In all analyses, the magnitude and direction of effects remained unaffected by diabetes status, after adjustment for other risk factors, and in other subgroup and meta-regression analyses. In cross-sectional and longitudinal studies, the severity of NAFLD was positively associated with CKD stages. Limitations of analysis are the relatively small size of studies utilizing liver histology and the suboptimal sensitivity of ultrasound and biochemistry for NAFLD detection in population-based studies.

CONCLUSION

The presence and severity of NAFLD are associated with an increased risk and severity of CKD. Please see later in the article for the Editors' Summary.

Chronic kidney disease and nonalcoholic Fatty liver disease-is there a link?

Research in recent years has led to the recognition of the importance of nonalcoholic fatty liver disease (NAFLD) and its relationship to the metabolic syndrome (MS). This has led to a growing interest in the potential prognostic value of NAFLD for adverse cardiovascular disease (CVD) outcome. On the other hand, searching for new risk factors for chronic kidney disease (CKD) development and progression is very important. Growing evidence suggests that the MS is an important factor in the pathogenesis of CKD. The best confirmation of this pathogenic link is hypertensive and diabetic nephropathy as the main causes of CKD. Furthermore, the possible link between NAFLD and CKD has also attracted research interest and recent data suggest an association between these two conditions. These findings have fuelled concerns that NAFLD may be a new and added risk factor for the development and progression of CKD. NAFLD and CKD share some important cardiometabolic risk factors and possible common pathophysiological mechanisms, and both are linked to an increased risk of incident CVD events. Therefore, common factors underlying the pathogenesis of NAFLD and CKD may be insulin resistance, oxidative stress, activation of rennin-angiotensin system, and inappropriate secretion of inflammatory cytokines by steatotic and inflamed liver.

Extrahepatic complications of nonalcoholic fatty liver disease

Nonalcoholic fatty liver disease (NAFLD) is a leading cause of chronic liver disease, and is strongly associated with the metabolic syndrome. In the last decade, it has become apparent that the clinical burden of NAFLD is not restricted to liver-related morbidity or mortality, and the majority of deaths in NAFLD patients are related to cardiovascular disease (CVD) and cancer. These findings have fuelled concerns that NAFLD may be a new, and added risk factor for extrahepatic diseases such as CVD, chronic kidney disease (CKD), colorectal cancer, endocrinopathies (including type 2 diabetes mellitus [T2DM] and thyroid dysfunction), and osteoporosis. In this review we critically appraise key studies on NAFLD-associated extrahepatic disease. There was marked heterogeneity between studies in study design (cross-sectional versus prospective; sample size; presence/absence of well-defined controls), population (ethnic diversity; community-based versus hospital-based cohorts), and method of NAFLD diagnosis (liver enzymes versus imaging versus biopsy). Taking this into account, the cumulative evidence to date suggests that individuals with NAFLD (specifically, nonalcoholic steatohepatitis) harbor an increased and independent risk of developing CVD, T2DM, CKD, and colorectal neoplasms. We propose future studies are necessary to better understand these risks, and suggest an example of a screening strategy.

Alkaline phosphatase is independently associated with renal function in normoalbuminuric type 1 diabetic patients

Nonalcoholic fatty liver disease (NAFLD) is associated with an increased prevalence of chronic kidney disease in patients with type 1 diabetes. The aim of this study was to explore the relationship between markers of NAFLD, namely concentrations of aspartate aminotransferase (AST), alanine aminotransferase (ALT), alkaline phosphatase (ALK), γ-glutamyltransferase (GGT), bilirubin, and renal function in type 1 diabetic patients. This study included 313 normoalbuminuric type 1 diabetic patients with estimated glomerular filtration rate (eGFR) >60 mL/min/1.73 m(2), without clinical evidence of cirrhosis or other causes of chronic liver disease and before any interventions with statins, angiotensin-converting enzyme (ACE) inhibitors or angiotensin II receptor blockers. ALT, GGT, and bilirubin levels were significantly higher in subjects in the highest quartile of serum creatinine compared to those in lowest quartile (21 vs. 20 U/L, 18 vs. 14 U/L, and 14 vs. 10 µmol/L, respectively, for all p < 0.05). ALK levels were significantly higher in subjects in the highest quartile of urinary albumin excretion rate compared to those in lowest quartile (71 vs. 69 U/L, p = 0.03), as well as in hyperfiltrating subjects compared to those with normal or mildly impaired eGFR (81 vs. 68 and 64 U/L, p < 0.001). In a multiple logistic regression model adjusted for age, sex, duration of diabetes, HbA1c, and body mass index (BMI), only ALK levels were significantly associated with disturbances in serum creatinine and eGFR in our subjects (p ≤ 0.007), with odds ratios of 0.98-1.02. NAFLD associated markers, particularly ALK, are associated with renal function in normoalbuminuric type 1 diabetic patients.

Nonalcoholic fatty liver disease (NAFLD): a new risk factor for adverse cardiovascular events in dialysis patients

Non-alcoholic fatty liver disease (NAFLD) is the most common liver disease in Western countries. Today it is believed that NAFLD is a hepatic manifestation of metabolic syndrome, and thus it is closely related to the cardiovascular morbidity and mortality. Cardiovascular diseases (CVD) are the leading cause of morbidity and mortality in patients with end-stage-renal disease (ESRD). NAFLD and ESRD share some important cardiometabolic risk factors and possible common pathophyisiological mechanisms, and are linked to an increased risk of incident CVD events. We hypothesize that the coexistence of these two conditions could lead to much faster progress of the aterogenic process. Furthermore, patients with ESRD who suffer from NAFLD have a much higher risk for the development of adverse CVD events. Given the high prevalence of NAFLD, and its tight association with other manifestations of the metabolic syndrome and thus cardiovascular complications, it is important to recognize and aggressively treat this condition in ESRD patients. To evaluate this hypothesis, we propose the use of non-invasive methods such as transient elastography (TE) (Fibroscan-CAP) for the detection and quantification of liver steatosis and fibrosis, as well as an abdominal ultrasound for detecting liver steatosis. We focus on their correlation with carotid intima-media thickness (IMT) and plaque as surrogate measures of increased cardiovascular risk in HD patients in order to investigate the association of NAFLD and increase risk of adverse CVD events. This evaluation will prove useful in assessing the risk in HD patients with NAFLD for increase CVD mortality.

Chronic kidney disease and nonalcoholic Fatty liver disease proven by transient elastography

BACKGROUND/AIM

Preliminary data suggest an association between chronic kidney disease (CKD) and non-alcoholic fatty liver disease (NAFLD). The aim of this study was to further investigate the association between NAFLD and decreased kidney function.

METHODS

A total of 62 patients with CKD were enrolled in the study. Liver stiffness was used to detect liver fibrosis and CAP (controlled attenuation parameter) was used to detect and quantify liver steatosis (Fibroscan®). NAFLD was defined by CAP values ≥238 dB.m(-1).

RESULTS

CKD stage III was present in 29 patients (46.8%) and CKD stage IV in 33 patients (53.2%). Out of 62 CKD patients 53 (85.5%) had NAFLD and of these 14/53 patients (26.4%) had also liver stiffness >7 kPa. The severity of liver steatosis was positively correlated with serum creatinine (r=0.399;p<0.01) and CRP (r=0.261; p<0.05) and negatively correlated with eGFR (r=-0.413; p<0.01) and serum iron concentration (r=-0.365; p<0.01).

CONCLUSION

The results suggest a high prevalence of NAFLD in CKD patients. The severity of liver steatosis is negatively correlated with kidney function. The study documents the value of ultrasonographic elastography as an effective non-invasive screening method for the diagnosis of NAFLD.

Increased risk of cardiovascular disease and chronic kidney disease in NAFLD

NAFLD is very common in the general population and its prevalence is increasing worldwide in parallel with the increasing incidences of obesity and metabolic diseases, mainly type 2 diabetes. In some cases, however, the diagnosis of NAFLD remains uncertain because other causes of liver disease are not easy to exclude in patients who are diagnosed with NAFLD after a biochemical or ultrasonographic analysis. Several studies have documented a strong association between NAFLD and traditional and nontraditional risk factors for cardiovascular disease (CVD) and chronic kidney disease (CKD). Accordingly, patients with NAFLD have an increased prevalence and incidence of both CVD and CKD. It is reasonable to believe that NAFLD, CVD and CKD share common risk factors (such as visceral obesity, insulin resistance, dysglycaemia, dyslipidaemia and hypertension) and therefore that NAFLD might simply be a marker rather than a causal risk factor of CVD and CKD. In this context, the identification of NAFLD might be an additional clinical feature to improve the stratification of patients for their risk of CVD and CKD. Growing evidence suggests that in patients with NAFLD, especially if NASH is present, several molecules released from the steatotic and inflamed liver might have pathogenic roles in the development of atherosclerosis and kidney damage. If these findings are confirmed by further studies, NAFLD could become a target for the prevention and treatment of CVD and CKD. NAFLD, whatever its role (marker or causal risk factor), is therefore a clinical condition that deserves greater attention from gastroenterologists, endocrinologists, cardiologists and nephrologists, as well as internists and general practitioners.

Nonalcoholic fatty liver disease associated with impairment of kidney function in nondiabetes population

BACKGROUND

Nonalcoholic fatty liver disease (NAFLD) is associated with the increased burden of kidney. However, there is still no large population study to explore the potential relationship between NAFLD and mild kidney function damage (MKFD) after adjusted for confounding factors. This study is to test the hypothesis that NAFLD is associated with MKFD under controlling the effects of confounding factors.

MATERIALS AND METHODS

Levels of serum fasting glucose, creatinine, cholesterol, triglyceride, alanine aminotransferase and aspartate aminotransferase were analyzed from 1412 Chinese Han adults. Questionnaire and physical examination were performed to explore the potential association of NAFLD with kidney function.

RESULTS

NAFLD was associated with impairment of kidney function. Multivariate-adjusted odds ratio illustrated that, compared to subjects with normal liver, NAFLD subjects had a significantly higher risk of MKFD with or without adjusted for blood glucose and other covariates (P = 0.041). Further results from multi-interaction analysis demonstrated that the underlying mechanisms linked NAFLD with impaired kidney function may be that they share common risk factors and similar pathological processes.

CONCLUSIONS

The most striking finding of this study is that NAFLD is negatively associated with kidney function, in nondiabetic population. NAFLD and MKFD may share similar risk factors and/or pathological processes.

Impaired renal function in morbid obese patients with nonalcoholic fatty liver disease

INTRODUCTION AND AIMS

Obesity is a common risk factor for nonalcoholic fatty liver disease (NAFLD) and chronic kidney disease (CKD). NAFLD and CKD have been associated in many epidemiological studies. We hypothesize that more severe liver disease, namely nonalcoholic steatohepatitis (NASH), is related with further renal impairment. We aimed to evaluate if changes in renal function were present in morbid obese patients with NAFLD.

METHODS

Prospective and consecutive recruitment of morbid obese patients with biopsy proven NAFLD obtained during bariatric surgery. Renal function was evaluated with CKD-Epidemiology Collaboration estimated glomerular filtration rate (eGFR). Plasmatic adiponectin, leptin and active ghrelin concentrations were determined.

RESULTS

One hundred and forty-eight patients were included of whom 25% had NASH and 75% simple steatosis. NASH patients were older, with higher body mass index and had more frequently metabolic syndrome and lower eGFR (97 ± 22 vs 106 ± 16 ml/min/1.73(2), P = 0.035). NASH conferred an odds ratio (OR) 3.0 (1.3-7.0) for eGFR < 90 and OR 9.7 (1.0-96.4) for eGFR < 60 ml/min/1.73(2). eGFR < 90 ml/min/1.73(2) associated with aspartate aminotransferase [OR 2.9 (1.1-7.6)] and γ-glutamyl transpeptidase elevation [OR 3.0 (1.3-7.2)], NASH [OR 3.0 (1.3-7.0)], any lobular inflammatory activity [OR 3.0 (1.3-7.0)] and severe fibrosis [OR 3.4 (1.1-10.8)]. Neither eGFR nor liver histology was associated with adipokines levels.

CONCLUSIONS

In morbid obese patients, NASH, particularly lobular inflammation and advanced fibrosis, associates with mild decreases in eGFR, suggesting a common inflammatory link between liver and renal lesion.

Nonalcoholic steatohepatitis and increased risk of chronic kidney disease

Nonalcoholic fatty liver disease (NAFLD) and chronic kidney disease (CKD) share common features. Both are associated with visceral obesity, type 2 diabetes mellitus, metabolic syndrome, and insulin resistance. However, the relationship between NAFLD and CKD is poorly understood. We examined the prevalence of and risk factors for CKD in patients with NAFLD. We analyzed 174 Japanese patients with liver biopsy-proven NAFLD using a cross-sectional design. Chronic kidney disease was defined as estimated glomerular filtration rate less than 60 mL/min per 1.73 m(2) and/or overt proteinuria. Of 174 NAFLD patients, 92 (53%) exhibited histologic characteristics of nonalcoholic steatohepatitis (NASH), the progressive form of NAFLD; and 82 (47%) had non-NASH NAFLD. Chronic kidney disease was present in 24 (14%) of 174 NAFLD patients. The prevalence of CKD was significantly higher in NASH patients (19 of 92; 21%) than non-NASH patients (5 of 82; 6%). The presence of CKD was associated with a higher body mass index and the presence of hypertension and NASH. Our results demonstrated a high prevalence of CKD among patients with NASH.

Risk of chronic kidney disease in patients with non-alcoholic fatty liver disease: is there a link?

Non-alcoholic fatty liver disease (NAFLD) has emerged as a growing public health problem worldwide. Increasing recognition of the importance of NAFLD and its association with the features of the metabolic syndrome has stimulated an interest in its putative role in the development and progression of chronic kidney disease (CKD). Accumulating evidence suggests that NAFLD and CKD share many important cardio-metabolic risk factors and common pathogenetic mechanisms and that NAFLD is associated with an increased prevalence and incidence of CKD. This association appears to be independent of obesity, hypertension, and other potentially confounding factors, and it occurs both in patients without diabetes and in those with diabetes. Although further research is needed to establish a definitive conclusion, these observations raise the possibility that NAFLD is not only a marker of CKD but also might play a part in the pathogenesis of CKD, possibly through the systemic release of several pro-inflammatory/pro-coagulant mediators from the steatotic/inflamed liver or through the contribution of NAFLD itself to insulin resistance and atherogenic dyslipidemia. However, given the heterogeneity and small number of observational longitudinal studies, further research is urgently required to corroborate the prognostic significance of NAFLD for the incidence of CKD, and to further elucidate the complex and intertwined mechanisms that link NAFLD and CKD. If confirmed in future large-scale prospective studies, the potential adverse impact of NAFLD on kidney disease progression will deserve particular attention, especially with respect to the implications for screening and surveillance strategies in the growing number of patients with NAFLD.

Relationship between kidney function and liver histology in subjects with nonalcoholic steatohepatitis

BACKGROUND AND OBJECTIVES

We assessed whether nonalcoholic steatohepatitis (NASH) diagnosed by liver biopsy is associated with decreased kidney function and whether such association is independent of insulin resistance and features of the metabolic syndrome.

DESIGN, SETTINGS, PARTICIPANTS, & MEASUREMENTS

We enrolled 80 consecutive overweight patients with biopsy-proven NASH and 80 nonsteatotic control subjects who were matched for age, gender, and body mass index. Chronic kidney disease (CKD) was defined as the presence of estimated GFR (eGFR) of ≤60 ml/min per 1.73 m(2) and/or abnormal albuminuria (i.e., urinary albumin/creatinine ratio ≥30 mg/g).

RESULTS

NASH patients had significantly (P < 0.001) lower eGFR (75.3 ± 12 versus 87.5 ± 6 ml/min per 1.73 m(2)) and a greater frequency of abnormal albuminuria (14 versus 2.5%) and CKD (25 versus 3.7%) than control subjects. The significant differences in eGFR, albuminuria, and CKD that were observed between the two groups were only slightly weakened after adjustment for age, gender, body mass index, smoking status, insulin resistance (by homeostasis model assessment), and components of the metabolic syndrome. Notably, histologic severity of NASH (i.e., fibrosis stage) was strongly associated with either decreasing eGFR or increasing albuminuria (P < 0.01 or less), independently of potential confounding factors.

CONCLUSIONS

Our findings suggest that patients with biopsy-proven NASH have moderately decreased eGFR and a higher frequency of abnormal albuminuria and CKD than matched control subjects and that the severity of NASH histology is associated with decreased kidney function, independently of traditional risk factors, insulin resistance, and components of the metabolic syndrome.