Nonalcoholic fatty liver disease is...

Nonalcoholic fatty liver disease is a universal condition associated with metabolic syndrome It is the greatest in number common cause of elevated liver enzyme in U adults, and is diagnosed after ruling revealed other causes of steatosis (fatty infiltration of liver), particularly infectious hepatitis and alcohol abuse. Liver biopsy may be considered if greater diagnostic and prognostic certainty is desired, particularly in patients with diabetes, patients who are morbidly obese, and in patients with an aspartate transaminase to alanine transaminase ratio greater than single because these patients are at risk of having more advanced disease. Weight los is the primary treatment for obese patients with nonalcoholic fatty liver disease. Medications used to treat insulin resistance, hyperlipidemia, and obesity have been shown to improve transaminase horizontals steatosis, and histologic findings. However, no treatments have been shown to affect patient-oriented outcomes

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Formerly called nonalcoholic steatohepatitis (NASH), nonalcoholic fatty liver disease now have references to a spectrum of diseases of the liver ranging from steatosis (i.e., fatty infiltration of the liver) to NASH (i.e., steatosis with inflammation and hepatocyte necrosis; Figure 1) to cirrhosis. Nonalcoholic fatty liver disease is the greatest in quantity common cause of elevated liver enzyme in adults in the United States (1) and the greatest in number common cause of cryptogenic cirrhosis, which is cirrhosis that cannot be explained from hepatitis, alcohol abuse, toxin prospect autoimmune disease, congenital liver disease, vascular outpouring obstruction, or biliary tract disease. (2) In the United States, estimates of the prevalence of nonalcoholic fatty liver disease range from 16 to 23 percent (3) However, in a new population-based study, 31 percent of the 2287 participants had steatosis diagnosed by dint of nuclear magnetic spectroscopy. (4) Patients who used alcohol were included in these numbers, unless there was no difference in steatosis between patients using alcohol and patients who did not use alcohol. The prevalence of nonalcoholic fatty liver disease becomes greater with increasing material part weight. Two thirds of patients with a material part mass index (BMI) of 30 kg by [m.sup.2] or greater, and more than 90 percent of patients with a BMI greater than 39 kg for [m.sup.2], have steatosis. (1) In the United States, up to 86 million someones who are obese may have steatohepatitis. (1)

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Nonalcoholic fatty liver disease has been associated with metabolic syndrome in observational studies and has been described as the hepatic composing of this syndrome. The greatest in number common risk factors for the growth of steatosis are obesity, diabetes, and hypertriglyceridemia. Other causes include toxins, medications, and inborn errors of metabolism (Table 1) (5)

Diagnosis

Differential Diagnosis

Numerous conditions cause liver enzyme elevation and steatosis. Table 2 lists the more frequent causes of elevated liver enzyme and their corresponding historical, physical, and laboratory findings.

The diagnosis of nonalcoholic fatty liver disease requires exclusion of alcoholic liver disease and viral hepatitis (Figure 2) Although many bodys likely have a combination of alcoholic and nonalcoholic fatty liver disease, the diagnosis of nonalcoholic fatty liver disease requires that daily alcohol intake be les than 20 g by means of day for women and les than 30 g for day for men. This equates to sum of two units standard alcoholic drinks per day for men and 15 standard alcoholic drinks by day for women. A standard drink contains 14 g of alcohol (eg 12 oz of beer, 5 oz of wine, or 15 oz of spirits).

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CLINICAL FINDINGS

most numerous patients with nonalcoholic fatty liver disease are asymptomatic, yet some may complain of fatigue and right upper quadrant abdominal fullnes or pain. Up to 50 percent of patients with this disease have hepatomegaly. (5) Patients with cirrhosis from nonalcoholic fatty liver disease will have findings similar to patients with cirrhosis from other causes.

LABORATORY EVALUATION

Laboratory abnormalities many times are the only sign of nonalcoholic fatty liver disease. The chiefly common abnormal laboratory test originates are elevated alanine transaminase (ALT) and aspartate transaminase (AST), usually undivided to four times the upper limits of normal. (5) However, patients with nonalcoholic fatty liver disease may have normal transaminase of the same heights The ratio of AST/ALT usually is les than 1 (in alcoholic liver disease, this ratio typically will be greater than 2) however may increase as the severity of the liver damage increases. (6) Alkaline phosphatase may be elevated up to twice the upper limit of normal (5); [gamma]-glutamyltransferase (GGT) also may be elevated.

IMAGING STUDIES

Imaging studies assist in the diagnosis of nonalcoholic fatty liver disease by the and of identifying fatty infiltrate in the liver. Ultrasonography of the liver has a sensitivity of 82 to 89 percent and a specificity of 93 percent for identifying fatty liver infiltrate. (78) If the pretest probability is 60 percent 95 percent of patients with an ultrasound positive for steatosis will have a fatty liver, compared with 20 percent of those who have a normal ultrasound.