Case Study #4
Non-alcoholic fatty liver disease: A weighty issue
Raphael B. Merriman
On completion of this activity, participants should be able to:
the role of liver biopsy in the evaluation of non-alcoholic fatty liver disease (NAFLD)
emerging non-invasive methods of assessing the severity of NAFLD
current therapeutic strategies
the current data for promising pharmacologic agents.
A 38-year-old Caucasian male is referred to the liver clinic with elevated aspartate transaminase (AST) and alanine transaminase (ALT) for the last 3 years. Serologic and biochemical markers for viral hepatitis and autoimmune liver disease and other metabolic liver diseases have been nega-tive. The patient has gained 22 kilograms since the age of 18. He consumes less than ﬁ ve standard drinks per week. His only symptoms were of an occasional right upper quadrant ache.
His past medical history is notable for reﬂ ux esophagitis, hypertension and hyperlipidemia. His family’s history is notable for diabetes, and ischemic heart disease but without liver disease. His medications are pantoprazole and lisinopril. His physical examination is notable for normal vital signs and a body mass index is 34.2. He is obese with mild acanthosis nigricans without cutaneous stigmata of chronic liver diseases. His liver span measures 18 centimeters without splenomegaly. The remainder of his physical examination was normal.
The initial investigations include laboratory data that showed total bilirubin of 0.7 mg/dL, AST of 68 IU/L, ALT of 120, IU/L alkaline phosphates of106 mg/dL, albumin 3.9 mg/dL, international normalized ratio (INR) of 1.1, platelet count 239 x 109/L, and fasting value for glucose of 121 mg/dL,ferritin 296 mg/dL, triglycerides 486 mg/dL, HDL 41 mg/dL, LDL 144 mg/dL. A liver ultrasound showed an enlarged liver, diffuselyheterogeneous, consistent with fatty inﬁ ltration.
1. What is the role of liver biopsy in the assessment of NAFLD?
2. What are the emerging non-invasive methods of assessing NAFLD?
Uniquely for so common a liver disease, in the assessment of NAFLD there is an absence of accurate and precise proven surrogate markers of disease presence or severity. Typically, a liver biopsy is pursued when aminotransaminases are persistently elevated in individuals who do not consume alcohol to excess when other causes of hepatitis have been excluded. Over 80% of these individuals will have NAFLD on biopsy. As a result, in suspected NAFLD, histology assumes a much greater role and importance, conﬁ rming the diagnosis, determining the grade and stage, thereby providing prognostic information.
In the assessment of non-alcoholic steatohepatitis (NASH), several clinical features are useful in predicting more advanced ﬁ brosis and may therefore help identify a sub-group of patients who would derive the most beneﬁ t from histologic assessment.1 These risk factors include age greater than 45, obesity, an AST-to-ALT ratio greater than one and the presence of diabetes.
The NAFLD Activity Score (NAS) is a new histopathologic scoring system for NASH activity developed by the National Institute of Health NASH Clinical Research Network.2 A modiﬁ cation of the Brunt
scoring system3, it combines simplicity and broad applicability and requires only H&E and Trichrome stains. The NAS ranges from 0 to 8 and is the unweighted sum of the scores for steatosis (0 to 3), lobular inﬂ ammation (0 to 3) and
Case Study #4
hepatocyte ballooning (0 to 2). An NAS <2 is not diagnostic of steatohepatitis, an NAS of 3–4 is suspicious or borderline, while an NAS >5 indicates deﬁ nite steatohepatitis. Fibrosis assessment is not included in this score in order to avoid mixing stage with grade in activity assessment. NAS is now being used in clinical trials to objectively measure histologic improvement.
The three components of the NAFLD activities score are steatosis, lobular inﬂ ammation and hepatocyte ballooning, examples of which are presented. Hepatocyte ballooning was included in the NAS as its presence suggests a greater likelihood of progression.
As NAFLD is common, more practical, non-invasive methods of assessment are urgently needed that could obviate the need for an invasive and potentially risk-prone biopsy.4 The ideal criteria for such markers would include liver-speciﬁ c measurements independent of metabolic alterations, tests that are easy to perform and minimally inﬂ uenced by urinary and biliary excretions, indices that are reﬂ ective of ﬁ brosis irrespective of causes, and measurements that are sensitive enough to discriminate between stages of ﬁ brosis and correlate with the dynamic changes. One proposed ﬁ brosis marker, the Fibrotest®, is a proprietary algorithm consisting of age, gender, alpha macroglobulin, apolipoprotein A1, haptoglobin, total
bilirubin and gamma GT.5 In one study, if the Fibrotest® score was >0.7, it has a 60% positive predictive value of ≥stage 3 ﬁ brosis; if <0.3, it had a 98% negative predictive value of ≥stage 3 ﬁ brosis. However, one-third of patients had an indeterminate score of 0.3–0.7. Serum markers of ﬁ brosis at their current state of development have limited utility.
Future developments in the non-invasive assessment of NAFLD include hepatic elastography and serum markers of hepatic inﬂ ammation. Hepatic elastography is a non-invasive assessment correlating the degree of liver stiffness to the degree of ﬁ brosis. An ultrasound pulse wave is transmitted through the liver and the wave velocity correlates with liver stiffness. One preliminary study reported by Kelleher showed good correlations between liver stiffness and ﬁ brosis stage. Pathogenic markers of hepatic inﬂ ammation include TNF-α and adiponectin, both of which affect insulin resistance. Cytokeratin 18 fragment level is a marker of apoptosis and a promising indicator of NASH activity.6 It is likely that multiple serum markers in combination will provide optimal correlation, though these remain to be accurately deﬁ ned and proven.
A liver biopsy is performed. This shows grade 2 steatosis, grade 1 ballooning, grade 2 lobular inﬂ ammation (NAS = 5) and stage 2 ﬁ brosis (scale 0–4). The ﬁ ndings are considered consistent with steatohepatitis.
Subsequent management issues
1. What are the therapeutic options for the management of NASH?
NASH is a complex, metabolic disease and many treatment options have been proposed. Controlled trials with relevant histologic endpoints of adequate power and extended follow-up have not been available thus far. Also, studies must include an assessment of the risk-beneﬁ t ratio of long-term therapy. Treatment of associated conditions such as diabetes and hyperlipidemia, though prudent, has not been proven to be necessarily effective.
In 1990, Wanless and colleagues were among the ﬁ rst researchers to highlight the strong association of insulin resistance with NAFLD.7 In one sentinel study, upon analysis of a liver at autopsy from an individual with diabetes who had undergone peritoneal dialysis for diabetic end stage renal disease with insulin added to the diasylate, fat was noted on the surface on the liver. At higher power this was conﬁ rmed and at further magniﬁ cation, a pattern of histology identical to NASH was identiﬁ ed, strongly suggesting that high local levels of insulin were associated with the development of the lesion now known as steatohepatitis. More recently Marchesini and colleagues compared blood glucose, plasma insulin and insulin resistance in subjects with non-alcoholic fatty liver disease and in control subjects.8 Non-alcoholic fatty liver disease was associated with higher levels of blood glucose, plasma insulin and measurements of insulin resistance, even in lean subjects with normal glucose tolerance.
Based upon that proposed pathophysiology, insulin-sensitizing drugs have been proposed in the treatment of NASH. Data from the main treatment trials are summarized.9,10 These studies were frequently non-controlled, inadequately powered and of short duration. Histologic endpoints have
Case Study #4
not always been available. Importantly, while improvements in steatosis and necroinﬂ ammation have somewhat consistently been shown, there has been no convincing, consistent improvement in hepatic ﬁ brosis demonstrated. Importantly, the NIH NASH Clinical Research Network treatment trial in non-diabetics entitled PIVENS, an adequately-powered, histologic–driven 3-arm study using pioglitizone, vitamin E or placebo is anticipated to provide key outcomes data in 2009.
Obesity is strongly associated with NAFLD. These CDC data show the rapidly rising prevalence of obesity among adults. The effect of weight loss as a therapeutic tool for the management of NASH has been incompletely studied. One of the limitations has been the difﬁ culty of sustaining weight loss over an adequate period of time.
However, bariatric surgery in morbidly obese patients often does result in sustained massive weight loss providing an opportunity to study the effect of such weight loss on NASH. Dixon and colleagues studied the effects of laparoscopic adjustable gastric banding and weight loss on NASH histology in obese patients leading to a mean 52% excess weight loss (34 kg) achieved over 2 years.11 A repeat-interval liver biopsy almost 2 years later showed signiﬁ cant improvements in lobular inﬂ ammation, steatosis and indices of the metabolic syndrome. Importantly, the number of patients with a ﬁ brosis score of >2, decreased from 18 prior to surgery to 3 two years later and the number fulﬁ lling a diagnosis of NASH declined from 23 to 4.
In summary, a liver biopsy is the only current means of deﬁ nitively conﬁ rming the diagnosis of NASH, providing unique prognostic information. The NAFLD activity score is a recently derived and validated histological scoring system for the objective assessment of NAFLD activity. There is yet no proven pharmacologic treatment for NASH. Insulin sensitizers appear promising – deﬁ nitive results are eagerly anticipated. In obese patients with NASH who have undergone bariatric surgery, sustained weight loss may be associated with substantial histologic improvement.
Repeat fasting glucose measurement on two occasions conﬁ rmed a new diagnosis of diabetes mellitus. A graded, prescribed exercise program in combination with caloric restriction was initiated, resulting in more than 9 kg weight loss over 26 weeks and weight loss was maintained for the next 8 months. Both AST and ALT fell into the normal range with normalization of glucose (and lipid) measurements without pharmacologic intervention. A repeat liver biopsy 14 months after the initial biopsy (at the time of the laparoscopic cholecystectomy) showed improved histologic ﬁ ndings
1. Angulo P, Keach JC, Batts KP, and Lindor KD. Independent predictors of liver ﬁ brosis in patients with non-alcoholic steatohepatitis. Hepatology
2. Kleiner DE, Brunt EM, Van Natta M, et al
. Non-alcoholic Steatohepatitis Clinical Research Network. Design and validation of a histological
scoring system for non-alcoholic fatty liver disease. Hepatology
2005; 41(6): 1313.
3. Brunt EM, Janney CG, Di Biscegli AM, et al
. Non-alcoholic steatohepatitis: A proposal for grading and staging the histological lesions.
Am J Gastroenterol
1999; 94(9): 2467.
4. Kelleher TB & Afdhal N. Non-invasive assessment of liver ﬁ brosis. Clin Liver Dis
2005; 9(4): 667.
5. Ratziu V, Massard J, Charlotte F, et al
. Diagnostic value of biochemical markers (FibroTest-FibroSURE) for the prediction of liver ﬁ brosis in
patients with non-alcoholic fatty liver disease. BMC Gastroenterol
2006; 6: 6.
6. Wieckowska A, Zein NN, Yerian LM, et al. In vivo
assessment of liver cell apoptosis as a novel biomarker of disease severity in non-alcoholic
fatty liver disease. Hepatology
2006 Jul; 44(1): 27.
7. Wanless IR & Lentz JS. Fatty liver hepatitis (steatohepatitis) and obesity: An autopsy study with analysis of risk factors. Hepatology
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8. Marchesini G, Brizi M, Morselli-Labate AM, et al
. Association of non-alcoholic fatty liver disease with insulin resistance. Am J Med
1999; 107(5): 450.
9. Kadayifci A, Merriman RB, Bass NM. Medical treatment of non-alcoholic steatohepatitis. Clin Liver Dis
2007; 11(1): 119.
10. Belfort R, Harrison SA, Brown K, et al
. A placebo-controlled trial of pioglitazone in subjects with non-alcoholic steatohepatitis. N Engl J Med
11. Dixon JB, Bhathal PS, Hughes NR, O’Brien PE. Non-alcoholic fatty liver disease: Improvement in liver histological analysis with weight loss.
2004; 39(6): 1647.
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The Geography of Poverty and Wealth by Jeffrey D. Sachs, Andrew D. Mellinger, and John L. Gallup, Scientific American, March 2001, pp.71-74. Why are some countries stupendously rich and others horrendously poor? Social theorists have been captivated by this question since the late 18th century, when Scottish economist Adam Smith addressed the issue in his magisterial work The Wealth of Natio