Biochemical tests of plasma for renal and liver functions were considered normal. Results of microscopic examination of feces was normal except for increased lipid content, and microbiologic test results were also negative. Antibody titers against toxoplasmosis, cytomegalovirus, herpes simplex virus types 1 and 2, and rubella were not suggestive. Serum lipids were found as follows: total cholesterol, 57 mg/dL (1.47 mmol/L); high-density lipoprotein, 31.3 mg/dL; low-density lipoprotein, 7.3 mg/dL; and very low-density lipoprotein, 18.4 mg/dL. Lipoprotein electrophoresis was found in normal limits; consequently, abetalipoproteinemia was not considered. Other disorders that cause malabsorption and failure to thrive, such as cystic fibrosis, were ruled out. Blood and urine amino acid concentrations were normal. Antigliadin immunoglobulin (Ig) A and IgG antibody titers were 58.4 (normal, 0-22) U/mL and 50.5 (normal, 0-27) U/mL, respectively. Endomysium IgA antibody was positive, which was highly suggestive for celiac disease (CD).