Relationship between non-alcoholic fatty liver disease and kidney function: A communication between two organs that needs further exploration

Fatty Liver Index is a valid predictor of non-alcoholic fatty liver disease (NAFLD) in pregnancy

BACKGROUND

Despite the evidence for adverse pregnancy outcomes, non-alcoholic fatty liver disease (NAFLD) is not routinely addressed in early pregnancy. The Fatty Liver Index (FLI) has been proposed as a screening tool for NAFLD in the general population. We aim to develop mathematical models for predicting NAFLD in pregnancy and validate the FLI for first-trimester pregnant women.

METHODS

Biochemical and biophysical parameters were analysed in pregnant women with period of gestation <12 weeks was done among Rajarata Pregnancy Cohort, Sri Lanka. Fatty liver was graded as (FLG) 0, I or II by ultrasound scan. Binary logistic regression models were employed to identify the factors predicting FLG-II. Six FLIs were developed to predict FLG-II. Validity of the FLIs was compared using the receiver operating characteristic curves.

RESULTS

The study sample consisted of 632 pregnant women with a mean age of 28.8 years (SD: 5.8 years). Age (OR: 1.6, 95% CI 1.1 to 2.3), body mass index (OR: 1.7, 95% CI 1.1 to 2.5) and gamma-glutamyl transferase levels (OR: 2.1, 95% CI 1.5 to 3.0) were the independent predictors of FLG-II. While the model with liver enzymes provided the best prediction of NAFLD (both FLG I and II) (area under the curve [(AUC]): -0.734), the highest AUC (0.84) for predicting FLG-II was observed with the full model (model with all parameters). The proposed budget model (AUC >0.81) is the best model for screening fatty liver in community health setup.

CONCLUSION

FLIs could be used as screening tools for NAFLD based on resource availability in different settings. External validation of the FLI and further investigation of the proposed FLI as a predictor of adverse pregnancy outcomes are recommended.

Renal resistive index in non-alcoholic fatty liver disease as an indicator of early renal affection

Background

Nonalcoholic fatty liver disease (NAFLD) is a possible risk factor for chronic kidney disease (CKD). Renal resistive index (RRI) which is a ratio of peak systolic and end diastolic velocity can test arterial stiffness and endothelial renal dysfunction. The aim of the work is to detect the relation between NAFLD and RRI as an indicator of early renal affection and its relation to the disease severity. This study included 150 subjects divided into 3 groups: patients with NASH, simple steatosis, and control group (50 patients each). All patients were subjected to full history taking, clinical examination, laboratory investigations, abdominal ultrasound examination, and RRI measurement.

Results

6.0% of NASH patients had significant fibrosis by NAFLD fibrosis score. RRI was significantly higher in NASH patients with fibrosis (mean = 0.74) than NASH patients without fibrosis (mean = 0.65) and patients with simple steatosis (mean = 0.63). It was the lowest in normal controls (mean = 0.61). There were significant correlations between RRI and age, BMI, serum lipids, liver enzymes, and NAFLD fibrosis score. Multiple linear regression analysis found that age and serum cholesterol were significant independent factors of increased RRI (p < 0.0001). RRI showed low diagnostic performance in differentiation between NASH and simple steatosis using ROC curve.

Conclusion

RRI was significantly higher in NASH patients with and without hepatic fibrosis. RRI correlates significantly with NAFLD fibrosis score. RRI can be used as an indicator of early renal affection in patients with NAFLD.

Nonalcoholic fatty liver disease alters microcystin-LR toxicokinetics and acute toxicity

Microcystin-LR (MCLR) is a cyanotoxin produced by blue-green algae that causes liver and kidney toxicities. MCLR toxicity is dependent on cellular uptake through the organic anion transporting polypeptide (OATP) transporters. Nonalcoholic fatty liver disease (NAFLD) progresses through multiple stages, alters expression of hepatic OATPs, and is associated with chronic kidney disease. The purpose of this study was to determine whether NAFLD increases systemic exposure to MCLR and influences acute liver and kidney toxicities. Rats were fed a control diet or two dietary models of NAFLD; methionine and choline deficient (MCD) or high fat/high cholesterol (HFHC). Two studies were performed in these groups: 1) a single dose intravenous toxicokinetic study (20 μg/kg), and 2) a single dose intraperitoneal toxicity study (60 μg/kg). Compared to control rats, plasma MCLR area under the concentration-time curve (AUC) in MCD rats doubled, whereas biliary clearance (Clbil) was unchanged; in contrast, plasma AUC in HFHC rats was unchanged, whereas Clbil approximately doubled. Less MCLR bound to PP2A was observed in the liver of MCD rats. This shift in exposure decreased the severity of liver pathology only in the MCD rats after a single toxic dose of MCLR (60 μg/kg). In contrast, the single toxic dose of MCLR increased hepatic inflammation, plasma cholesterol, proteinuria, and urinary KIM1 in HFHC rats more than MCLR exposed control rats. In conclusion, rodent models of NAFLD alter MCLR toxicokinetics and acute toxicity and may have implications for liver and kidney pathologies in NAFLD patients.

Renal dysfunction in patients with nonalcoholic fatty liver disease and risk factors

AIM

To assess the renal function in patients with nonalcoholic fatty liver disease (NAFLD) and to identify the risk factors for renal dysfunction.

METHODS

A total of 856 volunteers who underwent health examination were initially enrolled in this study to identify those with NAFLD. The biochemical indexes of patients with NAFLD and healthy volunteers were statistically analyzed, and the renal function with estimated glomerular filtration rate was calculated. In addition, the risk factors for renal damage were identified.

RESULTS

A total of 253 patients with NAFLD were identified, and the remaining 603 cases were used as a control group. There was no significant difference in serum BUN between the two groups (t = 1.678, P = 0.062), while other biochemical indexes differed significantly (P < 0.05). The prevalence of renal function impairment was higher in individuals with NAFLD compared to those without (28.8% vs 17.5%, P < 0.0001). Logistic regression analysis showed that NAFLD was associated with renal function impairment, even after adjustment for demographics and components of metabolic syndrome (OR = 2.85, 95%CI: 1.93-4.21, P = 0.000).

CONCLUSION

The biochemical indexes of NAFLD patients are significantly abnormal, and renal function impairment is associated with NAFLD. Patients with NAFLD should be regularly assessed for renal function to avoid progressing into chronic kidney disease and increasing the medical burden.

Association Between Urinary Alpha1-Microglobulin Levels and Nonalcoholic Fatty Liver Disease: A Cross-Sectional Study

BACKGROUND

We aimed to explore the association between urinary alpha1-microglobulin (A1M) levels and nonalcoholic fatty liver disease (NAFLD) in a Chinese population.

STUDY

We performed a cross-sectional study among 2,215 Chinese who attended their annual health examination at First Affiliated Hospital, College of Medicine, Zhejiang University. Urinary A1M-creatinine ratio and other clinical and laboratory parameters were measured.

RESULTS

A total of 20.9% of subjects fulfilled the diagnostic criteria of NAFLD. NAFLD subjects had significantly higher urinary A1M-creatinine ratios. These levels were positively associated with NAFLD prevalence. The association between A1M-creatinine ratio and NAFLD was independent of hyperglycemia status. Stepwise regression showed that urinary A1M-creatinine ratio was significantly associated with the risk for NAFLD. Urinary A1M-creatinine ratio was an independent factor predicting advanced fibrosis (FIB-4 ≥1.3) in NAFLD patients.

CONCLUSIONS

Our results showed a significant association between urinary A1M-creatinine ratio and NAFLD.

Non-Alcoholic Fatty Liver Disease in Africa and Middle East: An Attempt to Predict the Present and Future Implications on the Healthcare System

Non-alcoholic fatty liver disease (NAFLD) encompasses a group of hepatic diseases that range in severity. NAFLD is increasingly recognized as an epidemic among different populations, including those in Africa and the Middle East. The objective of this narrative review is to document the prevalence of and risk factors for NAFLD in Africa and the Middle East and the potential implications on the healthcare systems. An in-depth search on Google Scholar, Medline and PubMed was conducted using the terms "non-alcoholic fatty liver disease" and "non-alcoholic steatohepatitis", in addition to "prevalence and risk factors for NAFLD", with special emphasis on Africa and the Middle East countries. There were three types of epidemiological studies that included prevalence, risk factors and management/complications of NAFLD. There was noticeable variation in the prevalence of NAFLD among different countries, based on the variation in the prevalence of risk factors (type 2 diabetes, obesity, metabolic syndrome and dyslipidemia) and the diagnostic tool used in the study. However, the highest prevalence rate was reported in some Middle East countries. In Africa, there were few studies about NAFLD and most reported variable prevalence rates. There is an increasing prevalence of NAFLD as a result of the increasing risk factors, particularly in the Middle East, while in Africa, the situation is still unclear. Health providers in these regions are faced with many challenges that need urgent plans.

Non-alcoholic fatty liver disease: A sign of systemic disease

Non-alcoholic fatty liver disease (NAFLD) is the most common form of liver disease and leading cause of cirrhosis in the United States and developed countries. NAFLD is closely associated with obesity, insulin resistance and metabolic syndrome, significantly contributing to the exacerbation of the latter. Although NAFLD represents the hepatic component of metabolic syndrome, it can also be found in patients prior to their presentation with other manifestations of the syndrome. The pathogenesis of NAFLD is complex and closely intertwined with insulin resistance and obesity. Several mechanisms are undoubtedly involved in its pathogenesis and progression. In this review, we bring together the current understanding of the pathogenesis that makes NAFLD a systemic disease.

Using controlled attenuation parameter combined with ultrasound to survey non-alcoholic fatty liver disease in hemodialysis patients: A prospective cohort study

BACKGROUND AND AIMS

Controlled attenuation parameter (CAP) is a non-invasive method for measuring hepatic steatosis (HS). Non-alcoholic fatty liver disease (NAFLD) is closely related to cardiovascular diseases (CVDs). CVDs are the leading cause of morbidity and mortality in hemodialysis patients. The aim of this study was to investigate the prevalence of NAFLD in hemodialysis patients.

METHOD

We prospectively enrolled patients undergoing chronic hemodialysis, as well as patients with normal renal function who served as controls. The control group patients were referred by an endocrinologist to be tested for NAFLD; most of these patients had diabetes, hypertension, or dyslipidemia. We excluded those with excess alcohol intake, use of drugs known to induce HS, chronic viral hepatitis, or CAP failure. CAP ≥ 238 dB/m was used as a cutoff suggesting HS. An increased liver kidney contrast, as defined by ultrasound, was used to make the diagnosis of HS.

RESULTS

Three hundred and forty-three hemodialysis patients and 252 control group patients were enrolled. Among the hemodialysis patients, 192 (56.0%) had CAP- or ultrasound-identified HS compared with 91 (26.5%) who only had ultrasound-identified HS (P<0.001). Among the control group patients, 212 (84.1%) had CAP- or ultrasound-identified HS compared with 180 (71.4%) who only had ultrasound-identified HS (P<0.001).

CONCLUSIONS

The prevalence of NAFLD in the hemodialysis patients was 56%. The number of diagnoses of NAFLD made by using CAP combined with ultrasound was more than 2 times the number made with ultrasound alone in the hemodialysis patients. Therefore, we suggest the use of CAP combined with ultrasound to screen for NAFLD in hemodialysis patients.

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.

Intrahepatic triglyceride content is independently associated with chronic kidney disease in obese adults: A cross-sectional study

BACKGROUND

Non-alcoholic fatty liver disease (NAFLD) and chronic kidney disease (CKD) are associated with some common critical cardio-metabolic risk factors. The aim of this study was to explore the association between intrahepatic triglyceride (IHTG) content and CKD in obese subjects.

METHODS

A total of 1068 obese participants received anthropometric, biochemical measurements and hepatic ultrasonography. Of those, 485 participants received magnetic resonance spectroscopy ((1)H-MRS) for the determination of IHTG content. CKD was defined as a urinary albumin:creatinine ratio (UACR)≥30 mg/g and/or estimated glomerular filtration rate (eGFR)<60 mL/min per 1.73 m(2).

RESULTS

The prevalence of CKD was significantly higher in NAFLD subjects compared to subjects without NAFLD, while the prevalence of CKD was gradually increased as the IHTG content increased by quartiles (P for trend<0.001). After adjustment for multivariate metabolic factors, the risk of abnormal albuminuria and CKD was increased by 68% [OR (95% CI): 1.68 (1.21-2.33), P<0.01] and 54% [OR (95% CI): 1.54 (1.14-2.07), P<0.01] respectively per one standard deviation (SD) increase in IHTG content. The association between IHTG content and CKD was not changed by conventional risk factors, including age, BMI and hypertension (all P<0.05).

CONCLUSION

IHTG content is independently associated with CKD in obese adults.

Prevalence of and predictive factors for nonalcoholic fatty liver disease in Sudanese individuals with type 2 diabetes: Is metabolic syndrome the culprit?

BACKGROUND AND STUDY AIM

Non-alcoholic fatty liver disease (NAFLD) is a common global chronic liver condition. The prevalence of NAFLD among individuals with type 2 diabetes is estimated to be as high as 75%. The aim of this study was to determine the prevalence of NAFLD among individuals with type 2 diabetes in Sudan.

PATIENTS AND METHODS

This was a cross-sectional hospital-based study, which was carried out at the Jabir Abu-Elizz diabetic centre in Khartoum; 167 outpatients with type 2 diabetes were enrolled. NAFLD was diagnosed based on ultrasound, following exclusion of significant alcohol intake and secondary causes of liver diseases. NAFLD was defined as hepatic steatosis in the absence of alcohol intake, medication, previous liver disease and negative results for the serological test for hepatitis B and C. Logistic regression analysis was used to determine independent risk factors for the development of NAFLD in individuals with type 2 diabetes.

RESULTS

The number of female subjects was 89 (53.3%), and most subjects (145, 86.8%) were between the ages of 40 and 70 years. The overall prevalence of fatty liver among individuals with type 2 diabetes was found to be 50.3%. Age, duration of diabetes, hypertension and HbA1c levels appeared to have no impact on the prevalence of NAFLD. The possible predictors of NAFLD were overweight, obesity, central obesity, high triglyceride level and low high-density lipoprotein cholesterol (HDL-c) level. A higher prevalence of NAFLD was observed in individuals with three components of the metabolic syndrome.

CONCLUSION

NAFLD was observed in half of the diabetic population, and its occurrence correlates positively with metabolic syndrome risk factors.

Usefulness of liver test and controlled attenuation parameter in detection of nonalcoholic fatty liver disease in patients with chronic renal failure and coronary heart disease

BACKGROUND

In recent years, nonalcoholic fatty liver disease (NAFLD) was recognized as an important factor in chronic kidney disease (CKD) pathogenesis. The concentrations of serum aminotransferases in both chronic dialysis and chronic renal failure (CRF) patients most commonly fall within the lower end of the range of normal values. The aim of the present study was to investigate the usefulness of four liver tests and four biological scores in detection of NAFLD in comparison with transient elastography (TE) findings in different groups of patients.

METHODS

The study was cross-sectional analysis collected data from a single tertiary care center. Of 202 patents there were 52 patients with CKD, 50 patients with end-stage renal disease (ESRD) treated with haemodialysis (HD), 50 renal transplant recipients (RTRs) and 50 patients with proven coronary heart disease (CHD). Fifty sex- and age-matched individuals without NAFLD and with normal liver and kidney function tests served as controls. With the help of TE (FibroScan®, Echosense SA, Paris, France), liver stiffness was selected as the parameter to quantify liver fibrosis and Controlled Attenuation Parameter (CAP) was used to detect and quantify liver steatosis.

RESULTS

According to the CAP findings 76.9 %CKD patients, 82 %HD patients, 74 %RTRs and 69.1 % CHD patients had CAP > 238 dB.m(-1) and thus by definition NAFLD. We have found that ALT, AST and GGT levels were positively correlated with CAP values while ALT and AST showed positive correlation with liver stiffness acquired with TE only in CHD patients. According to TE findings APRI (AUC 0.796) and FIB-4 (AUC 0.790) scores were correlated with the presence of fibrosis, while HIS score was correlated with the presence of steatosis (AUC 0.867) only in CHD patients.

CONCLUSION

Liver tests and biological scores are not useful for NAFLD detection in CRF patients. TE with CAP provides the opportunity of noninvasive screening for NAFLD as well as liver fibrosis in patients with CRF.

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.

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.

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.