Sonographic measurement of the thickness of subcutaneous tissues in nonalcoholic fatty liver disease versus other chronic liver diseases

PURPOSE: To measure an average subcutaneous tissue thickness in nonalcoholic fatty liver disease (NAFLD) and other liver diseases using bedside sonography and make comparisons of thickness between groups. The study also addressed whether a cut-off subcutaneous tissue thickness exists below which NAFLD is unlikely. METHODS: Sonograph was performed on 113 consecutive patients with chronic liver disease. Diagnosis was derived from serological data combined with liver biopsy in all cases. Distance was measured between the skin and the liver surface and was labeled the subcutaneous tissue thickness. RESULTS: Of the 113 patients, 16 were diagnosed with NAFLD, 56 were diagnosed with chronic hepatitis C, 17 were diagnosed with autoimmune liver disease, and 24 had miscellaneous diagnoses (hepatitis B, hemochromatosis, granulomatous hepatitis, and cryptogenic hepatitis). The subcutaneous tissue thickness was 25.6 mm +/- 5.6 mm in NAFLD versus 19.5 mm +/- 5.2 in the non-NAFLD patients (p < 0.001). The subcutaneous tissue thickness of the HCV group was 20.2 mm +/- 4.8, and although it was not different than all other patients, it was different from the NAFLD patients (p < 0.01). Fifteen out of sixteen of the NAFLD patients had a greater than average subcutaneous tissue thickness (20 mm). CONCLUSIONS: A sonographically measured subcutaneous tissue thickness of less than 20 mm makes the diagnosis of NAFLD unlikely.