Abnormal circulating protein concentration Abnormal circulating fetuin A concentration 2020-11-28T22:09:58Z Any deviation from the normal concentration of fetuin A in the blood circulation. Fetuin-A (FetA) is a 64-kDa glycoprotein that is found in relatively high concentrations in human serum. In human adults, FetA is mainly expressed and secreted from the liver and adipose tissue. Epidemiologic research consistently observes elevated circulating FetA in obesity and related complications, such as type 2 diabetes mellitus, the metabolic syndrome, and nonalcoholic fatty liver disease.