Noninvasive in vivo quantitative assessment of fat content in human liver

Non-alcoholic fatty liver disease in young adult severely obese non-diabetic patients in South Italy

BACKGROUND/AIMS

In the absence of other causes, obesity increases the risk of liver disease. We evaluated the prevalence and degree of metabolic and hepatic abnormalities associated with non-alcoholic fatty liver disease (NAFLD) in type II-III obesity in a metropolitan area of South Italy.

METHODS

187 (81 M, 106 F) young adult non-diabetic obese patients, age range 18-50 years (mean 31.9 +/- 8.8), body mass index (BMI) > or =30 (mean 47.5 +/- 9.6), consecutively admitted from January 2000 to April 2003 to the Obesity Outpatients Clinic entered into the study. Patients were divided into two groups: (1) BMI 30.0-39.9, and (2) BMI> or =40. Ultrasound detected liver steatosis was classified as: (I) mild; (II) moderate, and (III) severe.

RESULTS

All patients, except 4, showed a variable degree of steatosis: mild was more frequent among females, severe steatosis present only in grade III obesity, with higher prevalence in males than in females (p < 0.001). Mean serum transaminases, in particular alanine aminotransferase (ALT), increased according to BMI and degree of steatosis. Homeostasis Model Assessment (HOMA) index, ferritin and fibrinogen levels increased with BMI, particularly in severe steatosis. In group 2, patients with BMI> or =40 showed a positive correlation between ferritin, aspartate aminotransferase (AST) (r = 0.46, p < 0.018), ALT (r = 0.41, p < 0.036) and gamma-glutamyltransferase (gammaGT) (r = 0.51, p < 0.007), between serum triglycerides (TG) and AST (r = 0.28, p < 0.036), ALT (r = 0.30, p < 0.02) and between HOMA and ALT (r = 0.30, p < 0.03) and gammaGT (r = 0.35, p < 0.012). In group 2 patients with severe steatosis the prevalence of metabolic syndrome according to Adult Treatment Panel III (ATP III) was 40%.

CONCLUSION

These data suggest that, in young adult non-diabetic grade III obese patients, fatty liver is always present and strictly related to insulin resistance which, in the presence of severe liver steatosis, is also related to serum ferritin.

Effects of oral 5-fluorouracil drugs on hepatic fat content in patients with colon cancer

RATIONALE AND OBJECTIVES

The association between hepatic steatosis and oral 5-fluorouracil (5-FU) agents is clinically recognized but has not been systematically studied. The aim of this study was to determine the effects of 5-FU on hepatic fat content in patients undergoing oral 5-FU therapy and to compare the effects in three subgroups of 5-FU drugs.

MATERIALS AND METHODS

Fifty-one patients with postoperative colon cancer (mean 61.1 years) were retrospectively studied. Forty-three patients were given adjuvant oral 5-FU therapy for a mean 3.3 years (5-FU group), and eight patients were not (control group). All patients underwent preoperative and postoperative abdominal computed tomography (CT) studies. The liver/spleen ratio was calculated from the CT attenuation values for the liver and spleen. We also compared the effects on hepatic appearance under CT of three 5-FU drugs: fluorouracil (n = 13), doxifluridine (n = 14), or UFT (a mixture of tegafur and uracil; n = 9).

RESULTS

In the 5-FU group, the mean CT values for the liver were significantly reduced relative to values before therapy (P < .01) and to those of the control group (P < .0001). Fifteen of 43 patients (34.9%) developed steatosis. Of the three 5-FU drugs, fluorouracil and doxifluridine caused a significant decrease in hepatic CT values.

CONCLUSION

5-FU caused a significant decrease in CT attenuation, indicating an increase in hepatic fat content, and was associated with very frequent hepatic steatosis. UFT seemed less likely to cause hepatic fatty infiltration. CT examination was useful for early detection of drug-induced side effects on liver even before lab abnormality or clinical manifestation is observed.

Relation between liver fat content and the rate of VLDL apolipoprotein B-100 synthesis in children with protein-energy malnutrition

BACKGROUND

Fatty infiltration of the liver is associated with an increased morbidity and mortality in children with severe protein-energy malnutrition (PEM), but its pathogenesis remains unclear. Although impaired synthesis of VLDL apolipoprotein B-100 (VLDL-apo B-100) is generally accepted as the pathogenetic mechanism, the rate of it synthesis has not been measured in children with PEM.

OBJECTIVE

The objective of the study was to ascertain the relation between the degree of hepatic steatosis and the rate of VLDL-apo B-100 synthesis in children with PEM.

DESIGN

The fractional and absolute rates of VLDL-apo B-100 synthesis were measured with a prime-constant intravenous infusion of [2H3]leucine in 13 severely malnourished children (8 boys and 5 girls) aged 7-18 mo. Hepatic fat content was estimated by computerized tomography scanning by using the ratio of liver to spleen (L:S) attenuation. The ratio is inversely related to hepatic fat content such that the lower the L:S, the greater the amount of fat in the liver.

RESULTS

There were significant inverse relations between L:S attenuation and VLDL-apo B-100 concentration (P < 0.02), the absolute rate of VLDL-apo B-100 synthesis (P < 0.02), and plasma triacylglycerol (P < 0.02) and serum cholesterol (P < 0.05) concentrations.

CONCLUSIONS

These results suggest that children with PEM synthesize VLDL-apo B-100 at a faster rate as the degree of hepatic fat infiltration increases. Thus, fatty infiltration of the liver in PEM is not due to a reduction in the synthesis of VLDL-apo B-100.

Noninvasive evaluation of graft steatosis in living donor liver transplantation

BACKGROUND

Hepatic steatosis affects graft function as well as postoperative recovery of donors in living donor liver transplantation. Liver macrovesicular steatosis in living donors was assessed using quantitative X-ray computed tomography (CT) analysis and histological examination of intraoperative liver biopsy.

METHODS

A total of 266 living donors with complete pretransplant CT data and intraoperative "time 0" biopsy were included in the study. Liver biopsy specimen obtained during donor operation was examined for macrovesicular steatosis and was classified as none; mild (<30%); moderate (30%-60%); or severe (>60%). Liver-to-spleen CT attenuation values ratio (L/S ratio) on noncontrast-CT was evaluated for its usefulness as an index of hepatic steatosis in comparison with other parameters including body mass index (BMI) and serum liver function tests (gamma-glutamyl transpeptidase, alanine aminotransferase, aspartate aminotransferase, cholinesterase, and total cholesterol) using receiver operating characteristic (ROC) analysis. RESULTS.: Histological grade of macrovesicular steatosis was none in 198 patients (74.4%), mild in 50 (18.8%), moderate in 15 (5.7%), and severe in 3 (1.1%). The median L/S ratios for the respective histological grades were 1.20 (range: 1.00-1.46), 1.12 (0.83-1.37), 1.01 (0.74-1.21), and 0.90 (0.70-0.99) (P<0.0001). The ROC curve for L/S ratio was located closest to the upper left corner, and the area under the curve of L/S ratio was significantly larger than that of any other preoperative variables.

CONCLUSION

L/S ratio calculated from preoperative CT can be a useful tool to discriminate hepatic macrovesicular steatosis. Based on the present results, the optimal cut-off value for L/S ratio to exclude more than moderate steatosis would be 1.1.

The hepatic regeneration power of mild steatotic grafts is not impaired in living-donor liver transplantation

The aim of this study was to assess histologic changes in steatotic grafts, regenerative capacity, and the outcome of steatotic grafts in living-donor liver transplantation (LDLT). Between September 2002 and February 2004, 55 cases of LDLT with a liver biopsy performed on the 10th postoperative day were enrolled. Patients were grouped according to the intraoperative histologic degree of macrovesicular steatosis (MaS) as follows: Group 1, <5% (n = 24); Group 2, 5 to 15% (n = 24); and Group 3, 15 to 30% (n = 7). The intraoperative microscopic findings and the findings on the 10th postoperative day were compared. Immunohistochemistry was performed using antibody of proliferating cell nuclear antigen (PCNA) and Ki-67 to assess the regeneration power of grafts on the 10th postoperative day. The histologic degree of MaS on postoperative day 10 decreased from 5.22 +/- 1.04% (mean +/- standard deviation) to 2.17 +/- 1.90 in Group 2 (P < .001) and from 21.4 +/- 8.02 to 4.43 +/- 2.70 in Group 3 (P = .003). The number of positively stained hepatocytes in 10 high power fields was 48.0 +/- 17.1, 53.8 +/- 14.4, and 51.5 +/- 4.1 in each group by PCNA (P = .681), and 24.0 +/- 14.0, 25.5 +/- 11.8, and 21.6 +/- 6.8 by Ki-67 (P = .825), respectively. No primary graft nonfunction (PNF) or delayed graft function (DGF) occurred. Major complications were comparable among groups. In conclusion, in LDLT, steatosis disappeared immediately after transplantation and hepatic regeneration power was not impaired in grafts with less than 30% of MaS. Furthermore, a mildly steatotic graft did not increase the risk of graft dysfunction or morbidity in LDLT.

Magnetic resonance spectroscopy to measure hepatic triglyceride content: prevalence of hepatic steatosis in the general population

Despite the increasing prevalence of nonalcoholic fatty liver disease (NAFLD), the criteria used to diagnose the disorder remain poorly defined. Localized proton magnetic resonance spectroscopy (MRS) accurately measures hepatic triglyceride content (HTGC) but has been used only in small research studies. Here, MRS was used to analyze the distribution of HTGC in 2,349 participants from the Dallas Heart Study (DHS). The reproducibility of the procedure was validated by showing that duplicate HTGC measurements were high correlated (r = 0.99, P < 0.001) and that the coefficient of variation between measurements was low (8.5%). Intake of a high-fat meal did not significantly affect the measurements, and values were similar when measurements were made from the right and left hepatic lobes. To determine the "upper limit of normal" for HTGC, the distribution of HTGC was examined in the 345 subjects from the DHS who had no identifiable risk factors for hepatic steatosis (nonobese, nondiabetic subjects with minimal alcohol consumption, normal liver function tests, and no known liver disease). The 95th percentile of HTGC in these subjects was 5.56%, which corresponds to a hepatic triglyceride level of 55.6 mg/g. With this value as a cutoff, the prevalence of hepatic steatosis in Dallas County was estimated to be 33.6%. Thus MRS provides a sensitive, quantitative, noninvasive method to measure HTGC and, when applied to a large urban US population, revealed a strikingly high prevalence of hepatic steatosis.

Is liver disease a threat to patients with metabolic disorders?

The association of metabolic disorders with liver disease is receiving increasing attention in the gastroenterological community. Cohort studies have shown that advanced liver disease may stem from metabolic disorders, via fatty liver, non-alcoholic steatohepatitis, cryptogenic cirrhosis, and eventually hepatocellular carcinoma. In both obesity and diabetes, deaths from cirrhosis are higher than expected, mainly in subjects with no or moderate alcohol consumption, but high rates of fatty liver disease have been associated with all features of the metabolic syndrome. Also the risk of hepatocellular carcinoma is higher than normal, being dependent on body mass index (BMI) in obesity, and independent of age, BMI, gender and race in diabetes. Finally, metabolic liver disease may interact with hepatitis C virus infection, increasing the risk of steatosis and liver disease progression, as well as reducing the chances of an effective antiviral treatment. There is evidence that treatments aimed at reducing insulin resistance are also effective in improving liver histology. Although cardiovascular disease remains the major cause of increased morbidity and excess mortality in metabolic disorders, the risk of progressive liver disease should no longer be underestimated, being a threat to millions of people at risk in the present epidemics of obesity and diabetes, and therapeutic strategies need to be tested.

Development of an unbiased method for the estimation of liver steatosis

BACKGROUND

Steatosis significantly contributes to an organ's transplantability. Livers with >30% fat content have a 25% chance of developing primary non-function (PNF). The current practice of evaluating a hematoxylin and eosin (H&E) stained donor biopsy by visual interpretation is subjective. We hypothesized that H&E staining of frozen sections fails to accurately estimate the degree of steatosis present within a given liver biopsy. To address this problem of evaluating steatosis in prospective donor organs, we developed a fast, user friendly computer methodology to objectively assess fat content based on the differential quantification of color pixels in Oil Red O (ORO) stained liver biopsies.

METHODS

The accuracy of human visual estimation of fat content by H&E and ORO stains was compared with computer-based measurements of the same slides from 25 frozen sections of donor biopsies.

RESULTS

Samples with a fat content >20% showed marked variation between human interpretation and computer analysis. There was also a significant difference in the human interpretation of fat based on the method of staining. This difference ranged from 3 to 37% with H&E.

DISCUSSION

Use of ORO resulted in a more consistent estimation of liver steatosis compared with H&E, but human interpretations failed to correlate with computer measurements. Such differences in fat content estimations might result in the rejection of a potentially transplantable organ or the acceptance of a marginal one. Ideally, our protocol can rapidly be applied to clinical practice for accurate and consistent measurement of fat in liver sections for the ultimate purpose of increasing the number of successful transplantable organs.

Metabolic effects of growth hormone therapy in an Alström syndrome patient

AIM

To investigate the metabolic effects of recombinant human growth hormone (rhGH) in an Alström syndrome patient with growth hormone deficiency.

METHODS

A 15-year-old Alström syndrome boy with growth hormone deficiency received rhGH therapy for 1 year. Biochemical parameters, including hepatic enzyme levels, lipid profiles, and insulin sensitivity, were measured. Body composition analysis and computed tomography scans of the liver were performed.

RESULTS

After 1 year of rhGH treatment, body fat mass, fat infiltration in the liver, and serum lipid profiles had all decreased. Insulin sensitivity and acanthosis nigricans improved.

CONCLUSION

rhGH therapy might have beneficial effects on body composition, liver fat content, lipid profiles, and insulin resistance in Alström syndrome patients, with improvement of the glucose homeostasis.

Liver fat is not a marker of metabolic risk in lean premenopausal women

We examined the independent associations among abdominal adipose tissue (AT) depots, liver fat, cardiorespiratory fitness (CRF), and metabolic risk factors in 86 lean premenopausal women. We measured abdominal AT and liver fat by computed tomography (CT), and CRF by a maximal treadmill exercise test. Liver fat was not related to any abdominal AT depot, metabolic risk factor, or CRF (P > .10). Visceral AT mass (kilograms) remained a significant (P < .05) predictor of total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C), TC/high-density lipoprotein cholesterol (HDL-C), and LDL-C/HDL-C after statistical adjustment for CRF. Abdominal subcutaneous AT mass was also a significant (P < .05) correlate of TC/HDL-C and LDL-C/HDL-C after control for CRF. Visceral AT remained a significant predictor (P < .05) of TC and LDL-C after control for abdominal subcutaneous AT. Conversely, subcutaneous AT did not remain a significant correlate after control for visceral AT. However, the deep subcutaneous AT depot remained significantly associated with LDL-C, TC/HDL-C, and LDL-C/HDL-C after control for visceral AT. In contrast, visceral AT remained correlated with triglycerides (TG) alone, after control for the deep subcutaneous AT. These observations suggest that liver fat is not a determinant of metabolic risk in lean women. Conversely, both visceral and the deep subcutaneous depot are determinants of metabolic risk in premenopausal woman despite the absence of obesity.

The clinical features, diagnosis and natural history of nonalcoholic fatty liver disease

Nonalcoholic fatty liver disease (NAFLD) has emerged as the most common chronic liver disease in the United States. The histologic spectrum of NAFLD ranges from steatosis liver alone to nonalcoholic steatohepatitis (NASH), which is the most serious form of NAFLD. NASH is a progressive fibrotic disease, in which cirrhosis and liver-related death occur in up to 20% and 12%, respectively, over a 10-year period. NASH-associated cirrhosis also can develop into subacute liver failure, progress to hepatocellular carcinoma, and reoccur post-transplantation. In contrast, steatosis alone has a more benign clinical course, although progression to cirrhosis has occurred in 3% of these patients. The major risk factors for fibrosis include diabetes or obesity, an aspartate aminotransferase/alanine aminotransferase ratio of greater than 1, age older than 50, and hepatic histology.

In vivo MRS measurement of liver lipid levels in mice

A magnetic resonance spectroscopy (MRS) procedure for in vivo measurement of lipid levels in mouse liver is described and validated. The method uses respiratory-gated, localized spectroscopy to collect proton spectra from voxels within the mouse liver. Bayesian probability theory analysis of these spectra allows the relative intensities of the lipid and water resonances within the liver to be accurately measured. All spectral data were corrected for measured spin-spin relaxation. A total of 48 mice were used in this study, including wild-type mice and two different transgenic mouse strains. Different groups of these mice were fed high-fat or low-fat diets or liquid diets with and without the addition of alcohol. Proton spectra were collected at baseline and, subsequently, every 4 weeks for up to 16 weeks. Immediately after the last MRS measurement, mice were killed and their livers analyzed for triglyceride level by conventional wet-chemistry methods. The excellent correlation between in vivo MRS and ex vivo wet-chemistry determinations of liver lipids validates the MRS method. These results clearly demonstrate that in vivo MRS will be an extremely valuable technique for longitudinal studies aimed at providing important insights into the genetic, environmental, and dietary factors affecting fat deposition and accumulation within the mouse liver.

Relationship between serum resistin concentrations and insulin resistance in nonobese, obese, and obese diabetic subjects

Early reports suggested that resistin is associated with obesity and insulin resistance in rodents. However, subsequent studies have not supported these findings. To our knowledge, the present study is the first assessment in human subjects of serum resistin and insulin sensitivity by the insulin clamp technique. Thirty-eight nonobese subjects [age, 23 +/- 4 yr; body mass index (BMI), 25.4 +/- 4.3 kg/m(2)], 12 obese subjects (age, 54 +/- 8 yr; BMI, 33.0 +/- 2.5 kg/m(2)), and 22 obese subjects with type 2 diabetes (age, 59 +/- 7 yr; BMI, 34.0 +/- 2.4 kg/m(2)) were studied. Serum resistin concentrations were not different among nonobese (4.1 +/- 1.7 ng/ml), obese (4.2 +/- 1.6 ng/ml), and obese diabetic subjects (3.7 +/- 1.2 ng/ml), and were not significantly correlated to glucose disposal rate during a hyperinsulinemic glucose clamp across groups. Serum resistin was, however, inversely related to insulin sensitivity in nonobese subjects only (r = -0.35; P = 0.05), although this association was lost after adjusting for percent body fat. Serum resistin was not related to percent fat, BMI, or fat cell size. A strong correlation was observed between serum resistin and resistin mRNA expression from abdominal sc adipose tissue in a separate group of obese subjects (r = 0.62; P < 0.01; n = 56). Although the exact function of resistin is unknown, we demonstrated only a weak relationship between resistin and insulin sensitivity in nonobese subjects, indicating that resistin is unlikely to be a major link between obesity and insulin resistance in humans.

Effects of moderate weight loss and orlistat on insulin resistance, regional adiposity, and fatty acids in type 2 diabetes

OBJECTIVE

Moderate weight loss is recommended for overweight and obese patients with type 2 diabetes, and conjunctive use of weight loss medication has been advocated. The current study examined weight loss-dependent and -independent effects of the intestinal lipase inhibitor orlistat at 6 months of treatment, using behavioral intervention (Int) combined with randomized, double-blinded, placebo (P)-controlled treatment with orlistat (O).

RESEARCH DESIGN AND METHODS

Metabolic control, insulin sensitivity (IS), regional fat distribution, and fat content in liver and muscle were measured in 39 volunteers with type 2 diabetes in whom all antidiabetic medication was withdrawn 1 month preceding randomization. Weight loss was equivalent in the Int+O and Int+P groups, respectively (-10.3 +/- 1.3 vs. -8.9 +/- 1.1%), and there were identical decreases in visceral adipose tissue (VAT), fat mass (FM), thigh adiposity, and hepatic steatosis.

RESULTS

Weight loss resulted in substantial improvement (P < 0.001) in HbA(1c) (-1.6 +/- 0.3 vs. -1.0 +/- 0.4%; NS between groups). IS improved significantly more with orlistat (Delta2.2 +/- 0.4 vs. Delta1.2 +/- 0.4 mg. min(-1). kg(-1) fat-free mass [FFM]; P < 0.05), and plasma free fatty acid (FFA) levels were strongly correlated with IS (r = 0.56; P < 0.001). Orlistat caused greater reductions in fasting plasma FFA (Delta-154 +/- 22 vs. Delta-51 +/- 33 micro mol/l; P < 0.05), insulin-suppressed FFA (Delta-119 +/- 23 vs. Delta-87 +/- 34 micro mol/l; P < 0.05), and fasting plasma glucose (FPG; -62 +/- 9 vs. -32 +/- 8 mg/dl; P = 0.02). Changes in HbA(1c) were correlated with DeltaIS (r = -0.41; P < 0.01) but not with weight loss per se.

CONCLUSIONS

At equivalent weight loss, conjunctive use of orlistat resulted in greater improvement in FFA levels and IS.

Association of nonalcoholic fatty liver disease with insulin resistance: is OGTT indicated in nonalcoholic fatty liver disease?

Nonalcoholic fatty liver disease (NAFLD) is frequently associated with type 2 diabetes mellitus, obesity, and dyslipidemia. We tested the hypothesis that there may be an association between NAFLD and insulin resistance (IR); and its correlation with glucose tolerance status of subjects who aren't known patients with diabetes. One hundred and seventy-six consecutive patients with elevated serum aminotransferase levels and bright liver were evaluated. Sixty-two patients were excluded from the study. Age, gender, height, weight, body mass index, waist circumferences, and family history of diabetes were recorded. Fasting plasma glucose, insulin, lipid profile were measured. A standard oral glucose tolerance test (OGTT) was performed and the index of IR was calculated according to the HOMA method. Patients with a normal glucose tolerance formed group 1 (64 patients) and patients with impaired or diabetic glucose tolerance group 2 (50 patients). Age, female sex, family history of type 2 diabetes, fasting insulin, fasting plasma glucose and HOMA-R index were statistically significantly different between the groups. Although the subjects in the study are not known patients with diabetes, the prevalence of impaired or diabetic glucose tolerance was prominent. In conclusion, performing OGTT in cases with nonalcoholic fatty liver disease may be useful for early screening of diabetes mellitus.

Fatty liver in type 2 diabetes mellitus: relation to regional adiposity, fatty acids, and insulin resistance

The current study was undertaken to examine metabolic and body composition correlates of fatty liver in type 2 diabetes mellitus (DM). Eighty-three men and women with type 2 DM [mean body mass index (BMI): 34 +/- 0.5 kg/m2] and without clinical or laboratory evidence of liver dysfunction had body composition assessments of fat mass (FM), visceral adipose tissue (VAT), liver and spleen computed tomography (CT) attenuation (ratio of liver to spleen), muscle CT attenuation, and thigh adiposity; these assessments were also performed in 12 lean and 15 obese nondiabetic volunteers. Insulin sensitivity was measured with a euglycemic insulin infusion (40 mU. m-2. min-1) combined with systemic indirect calorimetry to assess glucose and lipid oxidation, and with infusions of [2H2]glucose for assessment of endogenous glucose production. A majority of those with type 2 DM (63%) met CT criteria for fatty liver, compared with 20% of obese and none of the lean nondiabetic volunteers. Fatty liver was most strongly correlated with VAT (r = -0.57, P < 0.0001) and less strongly but significantly associated with BMI (r = -0.42, P < 0.001) and FM (r = -0.37, P < 0.001), but only weakly associated with subcutaneous adiposity (r = -0.29; P < 0.01). Fatty liver was also correlated with subfascial adiposity of skeletal muscle (r = -0.44; P < 0.01). Volunteers with type 2 DM and fatty liver were substantially more insulin resistant those with type 2 DM but without fatty liver (P < 0.001) and had higher levels of plasma free fatty acids (P < 0.01) and more severe dyslipidemia (P < 0.01), a pattern observed in both genders. Plasma levels of cytokines were increased in relation to fatty liver (r = -0.34; P < 0.01). In summary, fatty liver is relatively common in overweight and obese volunteers with type 2 DM and is an aspect of body composition related to severity of insulin resistance, dyslipidemia, and inflammatory markers.

Dual-echo, chemical shift gradient-echo magnetic resonance imaging to quantify hepatic steatosis: Implications for living liver donation

In living liver donation, a fatty liver poses risks for both recipient and donor. Currently, liver biopsy is the standard for assessing the presence and extent of steatosis. The goals of this study were to correlate a steatosis index derived from magnetic resonance imaging (MRI) to the histologic grade on biopsy as well as to determine the topographic distribution of steatosis within the liver. We examined the ability of dual-echo, chemical shift gradient-echo MRI to predict the degree of steatosis on liver biopsy. A total of 22 subjects received both a liver biopsy and detailed MRI evaluation. These individuals included 15 potential living donors and 7 patients with nonalcoholic fatty liver disease. MRI steatosis index was then compared with histologic grade on liver biopsy. The topographic distribution of hepatic steatosis was determined from those subjects in whom MRI detected hepatic steatosis. The steatosis index had a positive correlation with grade of steatosis on liver biopsy (correlation coefficient, 0.84). There was no significant variation in the degree of steatosis among segments. A steatosis index of >0.2 had good positive and negative predictive value for the presence of significant steatosis (>15%) on biopsy. Our quantitative MRI protocol can predict the degree of hepatic steatosis when it is minimal to moderate, and may obviate the need for liver biopsy for the purpose of quantification of steatosis in living donors. Fat saturation added to the MRI protocol may further improve diagnostic accuracy. This technique may be applicable to the larger population with hepatic steatosis.

Visceral fat and liver fat are independent predictors of metabolic risk factors in men

We examined the independent associations among abdominal adipose tissue (AT), liver fat, cardiorespiratory fitness (CRF), and lipid variables in 161 Caucasian men who had a wide variation in adiposity. We measured AT and liver fat by computed tomography and CRF by a maximal exercise test on a treadmill. Visceral AT remained a significant (P <or= 0.05) predictor of plasma triglycerides (TG), high-density-lipoprotein cholesterol (HDL-C), and total cholesterol (TC)/HDL-C ratio (TC/HDL-C) after statistical control for abdominal subcutaneous AT, CRF, and alcohol consumption. Abdominal subcutaneous AT was not a significant (P >or= 0.05) correlate of any lipid variable after control for visceral AT and CRF. Furthermore, subdivision of subcutaneous AT into deep and superficial depots did not alter these observations. Visceral AT was the strongest correlate of liver fat and remained so after control for abdominal subcutaneous AT, CRF, and alcohol consumption (r = -0.34, P < 0.01). In contrast, abdominal subcutaneous AT and CRF were not significant (P > 0.10) correlates of liver fat after control for visceral AT. Visceral AT remained a significant (P < 0.01) correlate of TG, HDL-C, and TC/HDL-C independent of liver fat. However, liver fat was also a significant correlate (P <or= 0.05) of fasting glucose and TG independent of visceral AT. These observations reinforce the importance of visceral obesity in the pathogenesis of dyslipidemia in men, and they suggest that visceral AT and liver fat carry independent health risk.

Non-alcoholic fatty liver syndrome: a hepatic consequence of common metabolic diseases

BACKGROUND AND AIMS

The association of liver steatosis with a number of common metabolic conditions has been suggested. The aim of the present study was to evaluate the clinical features of subjects with different severities of steatosis.

METHODS

The present study was performed in 282 consecutive patients with 'bright liver' at ultrasonography and in 58 subjects without steatosis. They had no history of alcohol abuse and negative tests for the presence of hepatitis B and C virus. Patients underwent clinical examination, anthropometry, laboratory tests and routine liver ultrasonography. Steatosis was graded as absent, mild, moderate and severe.

RESULTS

A progressive increase in the prevalence of obesity (P < 0.001), type 2 diabetes (P < 0.001), alanine aminotransferase (ALT) elevation (P < 0.001) and hypertriglyceridemia (P < 0.001), and a decrease of hypercholesterolemia (P < 0.05) was observed from the control group to the groups with mild, moderate and severe steatosis. More than half the subjects with liver steatosis had insulin resistance metabolic syndrome. Obesity, diabetes and hypertriglyceridemia were more common by 5.3-fold, 4.0-fold, and 6.7-fold, respectively, in subjects with severe steatosis, as compared to controls. Prevalence of obesity, diabetes and hyperlipidemia was significantly higher in subjects with fatty liver and ALT elevation.

CONCLUSION

Fatty liver can be considered as the hepatic consequence of common metabolic diseases.

Diagnosis of fatty liver disease: is biopsy necessary?

Non-alcoholic fatty liver disease is increasingly being recognized as an important and common condition, affecting approximately 20% of the general population. Although liver biopsy is currently the gold standard for diagnosis, there is a need for less invasive methods. Imaging by ultrasound, computerized tomography and magnetic resonance are all able to demonstrate fat. In this paper, these three imaging techniques are critically assessed. Ultrasound, although probably not the most reliable imaging method, has many advantages and, when positive, gives a high degree of certainty of the diagnosis depending on the prevalence of fatty liver in the population being studied. Unlike liver biopsy, none of these techniques is able to differentiate simple steatosis from non-alcoholic steatohepatitis.

Fatty liver in familial hypobetalipoproteinemia: triglyceride assembly into VLDL particles is affected by the extent of hepatic steatosis

Familial hypobetalipoproteinemia (FHBL) subjects may develop fatty liver. Liver fat was assessed in 21 FHBL with six different apolipoprotein B (apoB) truncations (apoB-4 to apoB-89) and 14 controls by magnetic resonance spectroscopy (MRS). Liver fat percentages were 16.7 +/- 11.5 and 3.3 +/- 2.9 (mean +/- SD) (P = 0.001). Liver fat percentage was positively correlated with body mass index, waist circumference, and areas under the insulin curves of 2 h glucose tolerance tests, suggesting that obesity may affect the severity of liver fat accumulation in both groups. Despite 5-fold differences in liver fat percentage, mean values for obesity and insulin indexes were similar. Thus, for similar degrees of obesity, FHBL subjects have more hepatic fat. VLDL-triglyceride (TG)-fatty acids arise from plasma and nonplasma sources (liver and splanchnic tissues). To assess the relative contributions of each, [2H2]palmitate was infused over 12 h in 13 FHBL subjects and 11 controls. Isotopic enrichment of plasma free palmitate and VLDL-TG-palmitate was determined by mass spectrometry. Non-plasma sources contributed 51 +/- 15% in FHBL and 37 +/- 13% in controls (P = 0.02). Correlations of liver fat percentage and percent VLDL-TG-palmitate from liver were r = 0.89 (P = 0.0001) for FHBL subjects and r = 0.69 (P = 0.01) for controls. Thus, apoB truncation-producing mutations result in fatty liver and in altered assembly of VLDL-TG.

Evaluation of living liver donors

Preoperative evaluation of donors for living-donor liver transplantation aims to select a suitable donor with optimal graft quality and to ensure donor safety. There are minor variations in the donor selection process among different centers, but the safety of the donor remains central to the entire process. The potential donors are evaluated in a stepwise manner including medical, physical, laboratory, psychosocial, and imaging assessment to disqualify unsuitable donors as early as possible in the evaluation process. The main goal of the imaging study is to provide an accurate picture of liver vascular anatomy and liver volume measurement for surgical guidance or for exclusion of unsuitable donors. All imaging studies can now be obtained using noninvasive modalities, thereby decreasing the risk associated with the donor evaluation process. This article describes the donor selection practice in our center including the details of the imaging evaluation.

Effects of tamoxifen on hepatic fat content and the development of hepatic steatosis in patients with breast cancer: high frequency of involvement and rapid reversal after completion of tamoxifen therapy

OBJECTIVE

A study was conducted on hepatic fat content to investigate the frequency and clinical course of hepatic steatosis induced by tamoxifen.

MATERIALS AND METHODS

Sixty-seven patients with breast cancer treated with adjuvant tamoxifen were included. The patients underwent postoperative annual abdominal CT, both with and without contrast enhancement, for 5 years. We retrospectively reviewed unenhanced CT images and obtained hepatic and splenic CT attenuation values to calculate the liver-spleen ratio. Hepatic steatosis was defined as a liver-spleen ratio of less than 0:9, and its degree was classified as mild (liver-spleen ratio, 0:5-0:9), moderate (0-0:5), or severe (<0). The pattern of steatosis was classified as generalized, lobar, segmental, or focal.

RESULTS

In the study population, hepatic CT values decreased during therapy (p < 0.0001, t test) and increased after therapy (p < 0.0001, paired t test). Twenty-nine patients (43.2%) developed hepatic steatosis within the first 2 years; its degree was mild in 16, moderate in nine, and severe in four. Seventeen patients showed a generalized pattern of steatosis, and the other 12 showed a lobar pattern. Twenty-three of these patients showed an increase in the liver-spleen ratio after therapy to within the normal range, with a mean recovery time of 1.2 years after therapy ended. None progressed to steatohepatitis or cirrhosis.

CONCLUSION

Tamoxifen had a statistically significant influence on hepatic fat content and was associated with frequent development of hepatic steatosis. Radiologists should be aware of this phenomenon and the possible occurrence of hepatic dysfunction and should differentiate steatosis from metastasis in postoperative patients with breast cancer.

The spectrum of fatty liver in obese children and the relationship of serum aminotransferases to severity of steatosis

OBJECTIVES

Non-alcoholic fatty liver disease is an emerging diagnosis in the pediatric population. Previously, ultrasonography and serum aminotransferases have been used to estimate prevalence of the disorder. A lack of concordance has been noted between these two diagnostic tests. To better understand the spectrum of fatty liver in obese children and the relationship of serum aminotransferases to the severity of steatosis, hepatic MRI was used to quantitate fat content.

METHODS

Twenty-two children, ages 6 to 18 years, with obesity (BMI > 95th percentile for age) and hepatomegaly (liver edge more than 2 cm below the right costal margin) underwent hepatic MRI for fat quantitation. Hepatic MRI was performed using a modification of the Dixon method that used a fast gradient echo sequence rather than traditional spin echo. Scan times were sufficiently brief to allow completion within a single breath hold. Serum aminotransferases were obtained within one month of MRI.

RESULTS

Twenty-one of 22 subjects had an elevated hepatic fat fraction. Seven of 7 subjects with a fat fraction of < or =18% had a normal serum ALT. Twelve of 13 subjects with fat fraction of >18% had an elevated serum ALT. Hepatic fat fraction correlated with serum ALT but did not correlate with age, BMI, or serum AST.

CONCLUSION

The spectrum of fatty liver is larger than detected by screening for abnormal serum aminotransferases alone. Abnormalities in serum ALT occur exclusively in more severe cases of fatty liver.

Nonalcoholic fatty liver disease (NAFLD) in children

Nonalcoholic fatty liver disease (NAFLD) is common in obese children and is a growing problem, given the increase in prevalence of obesity. NAFLD is also associated with diabetes, insulin resistance, hypercholesterolemia, and hypertriglyceridemia. Although mostly benign, some children with NAFLD develop fibrosis and cirrhosis, which necessitates close monitoring. Chronically elevated plasma liver enzyme levels is the most frequent finding. Ultrasound (US) examination allows confirmation of the diagnosis and it is useful for the follow-up. Gradual and sustained weight reduction is a management option that is worth trying initially. Other modalities of management, although interesting, await evidence as well as information on long-term benefits and effects. Sustained increase of transaminases despite weight reduction is a cause for concern and may require a liver biopsy both to assess severity of liver damage and for prognostic purposes.

Measuring body fat distribution and content in humans

PURPOSE OF REVIEW

In this review methods to measure the content and distribution of body fat or adipose tissue in humans are examined. The review particularly emphasizes methods to characterize regional fat distribution and ectopic fat (fat contained within other tissues) including specific applications and implications of region-specific or tissue-specific fat content.

RECENT FINDINGS

Recent novel applications of body composition methods, including in-vivo imaging modalities, magnetic resonance spectroscopy techniques, and direct measurement of extracted tissue have advanced our understanding of many health related issues including obesity, type 2 diabetes mellitus, progressive muscle weakness in aging and lipodystrophy. In particular, the accumulation of lipid within muscle and liver has received increased attention because of its association with metabolic dysregulation or impaired muscle function.

SUMMARY

Methods to quantify total body fat content in humans have provided considerable insight into obesity and related disorders, the aging process and its associated changes in function, and response to intervention. However, these methods have typically not been able to identify fat contained within specific regions of the body or within specific tissue. Direct quantification of fat distribution and fat within tissue in humans have been accomplished through in-vivo imaging techniques as well as invasive histological and biochemical approaches, and have advanced our understanding of many structure-function relationships. Further queries about human health and disease will undoubtedly lead to refinement of these methods and innovation of new body composition methodologies.

Effects of dietary medium-chain triacylglycerols on serum lipoproteins and biochemical parameters in healthy men

The objective of this study was to investigate effects of dietary medium-chain triacylglycerols (MCTs) on serum lipid levels, liver function, and hepatic fat accumulations in healthy men. Eleven subjects consumed 2200-2600 kcal daily, of which 70-80 g was fat; the fat included 40 g of MCTs or else 40 g of long-chain triacylglycerols (blended vegetable oil). The diet was followed for 4 weeks in this controlled double-blind study. At the end of the experiment, significant differences were not found in the concentrations of serum total cholesterol, very low density lipoprotein cholesterol, low density lipoprotein cholesterol, and high density lipoprotein cholesterol between the groups. Serum triglycerol levels were not significantly different in the groups. Adverse effects from ingestion of MCTs on liver functions, the liver-to-spleen ratio on computed tomography (an index of fatty liver), or results of blood tests were not seen. The results suggest that the long-term effects of dietary MCTs on serum cholesterol were similar to those of unsaturated fatty acids found abundantly in vegetable oil, and that consumption of MCTs in the amount of 40 g/day for a month does not cause liver fat accumulation or liver dysfunction.

Expanding the natural history of nonalcoholic steatohepatitis: from cryptogenic cirrhosis to hepatocellular carcinoma

BACKGROUND & AIMS

Nonalcoholic steatohepatitis (NASH) may progress to cirrhosis; whether NASH plays also a role in the development of hepatocellular carcinoma (HCC) is unknown.

METHODS

Among 641 cirrhosis-associated HCCs, we retrospectively identified 44 patients with cryptogenic cirrhosis (CC). Of these, 23 were actively followed up and were compared in a case-control study with viral- and alcohol-associated HCC. Family and personal history of diabetes, hypertension, coronary heart disease, dyslipidemia, obesity, and biochemical data were compared between groups. Iron status and presence of mutations in the HFE gene of familiar hemochromatosis were also determined.

RESULTS

Family history was not different in relation to etiology. The prevalence of obesity and diabetes was significantly higher in patients with CC. Although liver function was similar, CC patients had higher glucose, cholesterol, and triglyceride plasma levels, increased parameters of insulin resistance, and lower aminotransferase levels. Iron status and prevalence of mutations in the HFE gene did not differ. Logistic regression analysis identified in sequence hypertriglyceridemia, diabetes, and normal aminotransferases as independent factors associated with HCC arising in CC.

CONCLUSIONS

Features suggestive of NASH are more frequently observed in HCC arising in patients with CC than in age- and sex-matched HCC patients of well-defined viral or alcoholic etiology. HCC may represent a late complication of NASH-related cirrhosis.

Current practice regarding the use of fatty livers: a trans-Atlantic survey

A strong association exists between the presence of steatosis in a donor liver for transplantation and the development of primary nonfunction in the recipient. Despite this, appraisal of the donor remains one of the least scientific aspects of the transplantation process, and many centers base their practice on subjective opinion, rather than objective data. We conducted this survey to illuminate controversial issues and highlight the variation of opinion and practice policies both between and within the United Kingdom and the United States. A simple, anonymous, one-page, 10-question survey with tick-box answers was sent to every practicing liver transplant surgeon in the United Kingdom. The same form was sent by E-mail to liver transplant surgeons in the United States with a current E-mail address listed in the American Society of Transplant Surgeons registry. In the United Kingdom, 16 of 19 surgeons polled responded (84.2%) and thus were considered representative. From the United States, there were 78 respondents from 52 centers, representing all 11 United Network for Organ Sharing regions. We found that current practice policies differ not only between nations, but also among centers in each country. US surgeons generally follow a more conservative approach, with greater emphasis on histological assessment. Dichotomous opinions exist on the significance of microvesicular steatosis in both countries. Most evident from this survey is that more research in the field is required to help answer these questions and allow for the safe use of all viable livers.

Hepatic steatosis and its relationship to transplantation

Fatty infiltration of the liver is common in the brain-dead donor population and has a strong correlation with primary nonfunction after cold preservation, a condition that is catastrophic to liver transplant recipients. This literature review examines factors associated with the development, diagnosis, quantification, and clinical management of this difficult condition.

Correlation of abdominal fat accumulation and liver steatosis: importance of ultrasonographic and anthropometric measurements

PURPOSE

This study has two objectives: (1) using ultrasound (US) as a tool for measuring subcutaneous (S) and intra-abdominal; preperitoneal (P) and visceral (V) fat thickness. (2) Assessing the relationship between selected anthropometrical variables and US-measured S, P and V fat also evaluating the contribution of abdominal fat accumulation in development of liver steatosis.

METHODS AND MATERIALS

Sixty-eight obese patients (aged 43.9+/-9.3 years) and 40 non-obese subjects (aged 34.03+/-9.0 years) were recruited to this study. Height, weight (W), waist (WC) and hip circumferences were measured. Body mass index (BMI) and waist to hip ratio (WHR) were calculated. A linear-array probe (7.5 MHz) was used to measure S and P. A convex-array probe (3.5 MHz) was used for measuring V and assessing liver fatty infiltration.

RESULTS

In 45 (66%) patients, there were diffuse liver fatty changes. Liver steatosis showed significant correlation with V (r=0.57), P (r=0.38) and S (r=0.37). It also correlated with W (r=0.52), BMI (r=0.6), WC (r=0.45) (P<0.0001). V positively correlated with BMI (r=0.62), W (r=0.55), WC (r=0.52) and WHR (r=0.33). P correlated with WC (r=0.29), WHR (r=0.36) and W (r=0.34), but not with BMI, height and age. A significant correlation was found between S and BMI (r=0.73), W (r=0.65), and WC (r=0.57) (P<0.0001).

CONCLUSION

Obese patients showed thicker S, P, and V. Liver steatosis correlates significantly with both anthropometrical data; BMI, WHR, WC, and W, and with abdominal V, P, and S fat. V fat can be used as a good predictor for the possibility of different metabolic disorders and liver disturbances as steastosis.

Nonalcoholic fatty liver disease: a feature of the metabolic syndrome

Insulin sensitivity (euglycemic clamp, insulin infusion rate: 40 mU. m(-2). min(-1)) was studied in 30 subjects with biopsy-proven nonalcoholic fatty liver disease (NAFLD), normal glucose tolerance, and a BMI <30 kg/m(2). Of those 30 subjects, 9 had pure fatty liver and 21 had evidence of steatohepatitis. In addition, 10 patients with type 2 diabetes under good metabolic control and 10 healthy subjects were studied. Most NAFLD patients had central fat accumulation, increased triglycerides and uric acid, and low HDL cholesterol, irrespective of BMI. Glucose disposal during the clamp was reduced by nearly 50% in NAFLD patients, as well as in patients with normal body weight, to an extent similar to that of the type 2 diabetic patients. Basal free fatty acids were increased, whereas insulin-mediated suppression of lipolysis was less effective (-69% in NAFLD vs. -84% in control subjects; P = 0.003). Postabsorptive hepatic glucose production (HGP), measured by [6,6-(2)H(2)]glucose, was normal. In response to insulin infusion, HGP decreased by only 63% of basal in NAFLD vs. 84% in control subjects (P = 0.002). Compared with type 2 diabetic patients, NAFLD patients were characterized by lower basal HGP, but with similarly reduced insulin-mediated suppression of HGP. There was laboratory evidence of iron overload in many NAFLD patients, but clinical, histological, and biochemical data (including insulin sensitivity) were not correlated with iron status. Four subjects were heterozygous for mutation His63Asp of the HFE gene of familiar hemochromatosis. We concluded that NAFLD, in the presence of normoglycemia and normal or moderately increased body weight, is characterized by clinical and laboratory data similar to those found in diabetes and obesity. NAFLD may be considered an additional feature of the metabolic syndrome, with specific hepatic insulin resistance.

Assessment of donor fatty livers for liver transplantation

AIM

The effect of fatty liver on graft survival, especially with reference to macrovesicular and microvesicular steatosis, is still uncertain. This preliminarily study was designed to create a noninvasive method for the quantification of the hepatic fat content in vivo and to establish provisional criteria for the assessment of fatty donor livers before liver transplantation among transplant surgeons, radiologists, and pathologists.

METHODS AND MATERIALS

Different degrees of rat fatty liver model were established by feeding rats a diet deficient in choline and methionine for different periods of time. Computed tomography (CT) with test tubes containing variable percentages of fat equivalent substance were used to assess the severity of fatty change of the rat liver. This was then correlated with the histological classification, level of hepatic enzymes, and graft survival.

RESULTS

Linear correlation between the fat volume fraction added to the test tubes and CT density were found. The process of producing a fatty liver via diet alteration peaked at week 3. At this time hepatic enzymes, radiological fat content, and posttransplantation survival were worse (P=0.013), compared with other time points. Radiological assessment of fatty liver correlated well with survival and serum glutamic oxaloacetic transaminase and glutamic pyruvate transaminase levels.

CONCLUSION

Severe microvesicular steatosis does not influence recipient survival, however, macrovesicular steatosis affects graft survival. Caliber CT is a practical and simple method that allows an accurate noninvasive quantitative assessment of hepatic fatty infiltration. It has potential to be a useful parameter for the assessment of donor livers for clinical liver transplantation.

Body mass index as a predictor of hepatic steatosis in living liver donors

Evaluation of the living donor for liver transplantation is a complex process involving such invasive studies as liver biopsy and angiography. It is important to establish the likelihood and extent of hepatic steatosis in living donors by clinical, imaging, and biochemical parameters to avoid performing a liver biopsy, if possible. In this study, the predictive value of body mass index (BMI), liver chemistry tests, and imaging studies was compared with liver histological examination in 33 potential living donors. Patients were grouped and compared based on their BMI (<25, 25 to 28, >28). No patient with a BMI less than 25 had hepatic steatosis. Of patients with a BMI of 25 to 28, steatosis was found on biopsy in 3 of 9 patients. Thirteen of 17 patients (76%) with a BMI greater than 28 had hepatic steatosis on liver biopsy. There was a significant correlation between BMI and overall grade of steatosis (R = 0.49). All subjects with steatosis detected on magnetic resonance imaging (MRI) or computed tomography (CT) had steatosis on biopsy, and all but 2 such patients had greater than 10% steatosis on biopsy. Conversely, 30% of patients in the MRI group and 24% of patients in the CT group failed to show hepatic steatosis when it was present on biopsy. Thus, it appears that liver biopsy could be avoided in subjects with a normal BMI and absence of risk factors. Individuals with a high BMI should undergo liver biopsy because biochemical and imaging data are currently inadequate to determine the extent of steatosis. Future studies should aim at improving the sensitivity of imaging techniques in the diagnosis of steatosis.

Spleen enlargement in patients with nonalcoholic fatty liver: correlation between degree of fatty infiltration in liver and size of spleen

Our purpose was to determine if there is an association between nonalcoholic fatty liver and spleen enlargement. Spleen volume was measured by computed tomography (CT) in 32 patients with nonalcoholic fatty liver (23 men and 9 women; age, 41.6+/-12.1, range, 22-69 years) and 34 patients with normal liver (19 men and 15 women; age, 51.1+/-16.2, range, 14-86 years). The values were compared with the patient's demographic data, the liver-to-spleen (L/S) ratio of CT Hounsefield unit measurements, and the results of liver function tests. Diagnosis of fatty liver was made if the L/S ratio was less than 1.0. The mean spleen volume was 73.0+/-24.4 cm3 (range, 21.1-106.1) in normal subjects and 141.2+/-54.1 cm3 (range, 44.1-267.3) in patients with fatty liver (P<0.0001). Multivariate linear regression analysis identified that only the L/S ratio (P<0.0001) and age (P<0.01) were significantly correlated with spleen volume. Using forward selection stepwise regression, the L/S ratio entered first (beta = -0.634) and age second (beta = -0.293). In conclusion, spleen enlargement was commonly seen in patients with nonalcoholic fatty liver, and the recognition of this association may halt further attempts to evaluate the cause of spleen enlargement.

Prevalence of and risk factors for hepatic steatosis in Northern Italy

BACKGROUND

Although hepatic steatosis is seen with increasing frequency in clinical practice, its prevalence and risk factors are unknown.

OBJECTIVE

To investigate the prevalence of and risk factors for hepatic steatosis, such as alcohol consumption and obesity.

DESIGN

Cross-sectional, observational study.

SETTING

Participants in the Dionysos Study.

PATIENTS

257 participants assigned to one of four categories (67 controls, 66 obese persons, 69 heavy drinkers, and 55 obese heavy drinkers).

MEASUREMENTS

Ethanol intake, assessed by a validated questionnaire and expressed as daily (g/d) and lifetime (kg) consumption, and body mass, expressed as body mass index. Biochemical tests of liver and metabolic function and hepatic ultrasonography were done.

RESULTS

The prevalence of steatosis was increased in heavy drinkers (46.4% [95% CI, 34% to 59%]) and obese persons (75.8% [CI, 63% to 85%]) compared with controls (16.4% [CI, 8% to 25%]). Steatosis was found in 94.5% (CI, 85% to 99%) of obese heavy drinkers. Compared with controls, the risk for steatosis was higher by 2.8-fold (CI, 1.4-fold to 7.1-fold) in heavy drinkers, 4.6-fold (CI, 2.5-fold to 11.0-fold) in obese persons, and 5.8-fold (CI, 3.2-fold to 12.3-fold) in persons who were obese and drank heavily. In heavy drinkers, obesity increased the risk for steatosis by twofold (CI, 1.5-fold to 3.0-fold) (P < 0.001), but heavy drinking was associated with only a 1.3-fold (CI, 1.02-fold to 1.6-fold) increase in risk in obese persons (P = 0.0053). Elevated alanine aminotransferase and triglyceride levels are the most reliable markers of steatosis.

CONCLUSIONS

Steatosis is frequently encountered in healthy persons and is almost always present in obese persons who drink more than 60 g of alcohol per day. Steatosis is more strongly associated with obesity than with heavy drinking, suggesting a greater role of overweight than alcohol consumption in accumulation of fat in the liver.

Spleen enlargement in patients with nonalcoholic fatty liver: correlation between degree of fatty infiltration in liver and size of spleen

Our purpose was to determine if there is an association between nonalcoholic fatty liver and spleen enlargement. Spleen volume was measured by computed tomography (CT) in 32 patients with nonalcoholic fatty liver (23 men and 9 women; age, 41.6+/-12.1, range, 22-69 years) and 34 patients with normal liver (19 men and 15 women; age, 51.1+/-16.2, range, 14-86 years). The values were compared with the patient's demographic data, the liver-to-spleen (L/S) ratio of CT Hounsefield unit measurements, and the results of liver function tests. Diagnosis of fatty liver was made if the L/S ratio was less than 1.0. The mean spleen volume was 73.0+/-24.4 cm3 (range, 21.1-106.1) in normal subjects and 141.2+/-54.1 cm3 (range, 44.1-267.3) in patients with fatty liver (P<0.0001). Multivariate linear regression analysis identified that only the L/S ratio (P<0.0001) and age (P<0.01) were significantly correlated with spleen volume. Using forward selection stepwise regression, the L/S ratio entered first (beta = -0.634) and age second (beta = -0.293). In conclusion, spleen enlargement was commonly seen in patients with nonalcoholic fatty liver, and the recognition of this association may halt further attempts to evaluate the cause of spleen enlargement.

Association of nonalcoholic fatty liver disease with insulin resistance

BACKGROUND AND PURPOSE

Nonalcoholic fatty liver disease is frequently associated with type 2 diabetes mellitus, obesity, and dyslipidemia, but some patients have normal glucose tolerance or normal weight. We tested the hypothesis that there is an association between nonalcoholic fatty liver disease and insulin resistance that is independent of diabetes and obesity.

SUBJECTS AND METHODS

We measured anthropometric and metabolic variables in 46 patients with chronically elevated serum aminotransferase levels, "bright liver" on ultrasound scan, and normal glucose tolerance. Indexes of insulin resistance and secretion were determined using the homeostasis model assessment method. They were compared with 92 normal subjects who were matched for age and sex.

RESULTS

Patients with nonalcoholic fatty liver disease were characterized by fasting and glucose-induced hyperinsulinemia, insulin resistance, postload hypoglycemia, and hypertriglyceridemia. Insulin resistance [odds ratio (OR) = 15 per percent increase, 95% confidence interval (CI): 3.0 to 70], fasting triglyceride level (OR = 3.1 per mmol/liter increase, 95% CI: 1.1 to 8.9), 180-minute blood glucose level (OR = 4.3 per mmol/ liter decrease, 95% CI: 1.6 to 12), and average insulin concentration in response to oral glucose (OR = 3.0 per 100 pmol/liter increase, 95% CI: 1.5 to 6.2) were independently associated with nonalcoholic fatty liver disease. The exclusion of overweight and obese subjects did not change the results.

CONCLUSION

Nonalcoholic fatty liver disease is associated with insulin resistance and hyperinsulinemia even in lean subjects with normal glucose tolerance. Genetic factors that reduce insulin sensitivity and increase serum triglyceride levels may be responsible for its development.

Ultrasound backscatter and attenuation in human liver with diffuse disease

Ultrasound backscatter and attenuation in the liver were measured in patients with diffuse liver disease and in 35 volunteers who had no history of liver ailments. Measurements were done using radiofrequency (RF) echo signals derived from a clinical scanner; a reference phantom was scanned to account for effects of gain, transmit-receive frequency response and transducer beam patterns on echo data. The mean backscatter coefficient at 3 MHz in livers of 7 patients with fatty infiltration was 6.8 x 10(-3) cm(-1)sr(-1) compared to a mean of 0.5 x 10(-3) cm(-1)sr(-1) in healthy patients. Mean attenuation at 3 MHz was 2.54 dB/cm in fatty livers compared to 1.66 dB/cm in healthy patients. A total of 7 patients with end-stage liver disease (cirrhosis) had attenuation values similar to those in the healthy group, and their mean liver backscatter was somewhat greater than the mean backscatter for healthy livers. Quantitating both backscatter and attenuation should be considered for detecting fatty infiltration; additional processing methods are needed to differentiate cirrhotic changes on the basis of acoustic signals.