肝功能正常者之非酒精性脂肪肝的相關因子探討

The Correlates of Nonalcoholic Fatty Liver Disease in Subjects with Normal Liver Function

目的：非酒精性脂肪肝（nonalcoholic fatty liver disease, NAFLD）是常見的慢性肝臟疾病。麩丙酮酸轉胺酶（alanine aminotransferase、ALT）上升是NAFLD的臨床表現之一，然而ALT數值容易變動，可能回復到正常，因此臨床醫師常因肝功能正常而忽略了NAFLD的存在。因此本研究的目的為了解肝功能正常者NAFLD的相關因子。方法：本研究以2003年1月至2006年10月間接受健康檢查的成年受檢者，每位受檢者均接受醫師詢問病史與理學檢查，並完成結構式問卷。所有受檢者隔夜空腹至少8小時，接受腹部超音波檢查及抽血檢驗全血球計數、血脂質、尿酸、空腹血糖、糖化血色素、肝腎功能及甲狀腺功能檢查。結果：經排除不符條件者，計有2,668位肝功能正常者為研究對象，其中815位具有NAFLD。結果顯示單變項分析中，有無NAFLD兩組間在年齡、性別、身體質量指數、收縮壓、舒張壓、麩丙酮酸轉胺酶（ALT）、門冬氨酸轉氨酶（aspartate aminotransferase, AST）、空腹血糖、尿酸、血脂質、吸菸及婚姻狀況皆有顯著的差異。多變項分析依男女性別分開進行非酒精性脂肪肝與臨床各變項之複邏輯回歸分析，結果顯示男性的年齡越大、舒張壓越高、ALT/AST比值越大、身體質量指數、空腹血糖、尿酸及三酸甘油酯越高、高密度脂蛋白膽固醇越低與NAFLD有獨立的相關性。女性的身體質量指數、ALT/AST比值、空腹血糖、尿酸、三酸甘油酯及離婚／鰥寡與NAFLD有獨立的正相關。結論：身體質量指數、ALT/AST、空腹血糖、尿酸、及三酸甘油脂為肝功能正常者脂肪肝的重要相關因子。當上述相關因子出現越多或其嚴重程度越高者，其有NAFLD的風險越高。

Objective: Nonalcoholic fatty liver disease (NAFLD) is a common chronic liver disease. Although elevated alanine aminotransferase level is a manifestation of NAFLD, it may fluctuate and return to normal level. Physicians may overlook the presence of NAFLD if the patient has normal liver function test. Therefore, the aim of this study was to evaluate the prevalence and correlates of NAFLD in subjects with normal liver function test. Methods: The subjects were recruited from the health examination center of National Cheng Kung Hospital from 2003 to 2006. Fasting plasma glucose, lipid profile, uric acid, liver and kidney function, thyroid stimulating hormone and abdominal ultrasound examination were performed after at least 8-hour fast. Results: After excluding non-eligible subjects, 2668 subjects with normal aspartate aminotransferase (AST) and ALT level were included for final analysis and 815 subjects (30.5%) had NAFLD. There were significant differences in age, gender, cigarette consumption, marital status, body mass index (BMI), systolic and diastolic blood pressures, fasting plasma glucose, AST, ALT, uric acid, and lipid profile between subjects with and without NAFLD. In male subjects, multivariate analysis showed age, diastolic blood pressure, ALT/AST ratio, BMI, fasting plasma glucose, uric acid, triglyceride and lower high density lipoprotein cholesterol were the positively associated with NAFLD. In female, BMI, ALT/AST ratio, fasting plasma glucose, uric acid, and triglyceride, and divorce/widow were the independently positive correlates of NAFLD. Conclusions: BMI, ALT/AST ratio, fasting plasma glucose, uric acid, and friglycerid were the important associated factors of NAFLD in subjects with normal liver function. The risk of NAFLD increases when the severity and the number of the above associated factors increase.