Hypoproteinemia/metabolism; Liver/metabolism; Serum Albumin/biosynthesis; Adolescent; Amino Acid Metabolism, Inborn Errors/metabolism; Anaphylaxis/metabolism; Anorexia Nervosa/metabolism; Bile Ducts/abnormalities; Child; Child, Preschool; Chromatography, Gel; Colitis, Ulcerative/metabolism; Cystic Fibrosis/metabolism; Female; Glomerulonephritis/metabolism; Humans; Infant; Injections, Intravenous; Intellectual Disability/metabolism; Kinetics; Liver Cirrhosis/metabolism; Liver Cirrhosis, Biliary/metabolism; Liver Diseases/metabolism; Male; Methionine/metabolism; Nephrotic Syndrome/metabolism; Psychomotor Disorders/metabolism; Purpura/metabolism; Radioisotopes; Selenium; Spectrophotometry; Tyrosine/metabolism