Levels of protein in the blood are an indicator of a person's health, and someone with abnormal protein levels may have nutritional problems, or kidney or liver diseases. Protein levels can be influenced by several extraneous factors. A new study published in Nature Communications shows how genetic, clinical, and lifestyle factors affect protein levels in the bloodstream. The findings will provide doctors with biomarkers that may help them identify diseases.

Biomarkers are used to indicate the physiologic state of a specific part of the body. Protein biomarkers have been used extensively to diagnose and detect diseases, target molecular medical interventions, and assess positive or negative responses to medication. For example, testing for levels of a protein known as prostate specific antigen (PSA) can help doctors detect a person's risk of prostate cancer. Biomarkers are specific to their location in the body, where they have designated roles. When diagnosing a disease, tests usually detect abnormal protein levels.

In order to test the efficacy of 92 protein biomarkers, and to determine whether they are influenced by genetic, clinical, or lifestyle factors, researchers at Uppsala University analyzed biomarkers for cancer and inflammation. The study was conducted on about 1,000 healthy individuals, and found that hereditary factors play a significant role in more than 75 percent of the proteins. A detailed genetic analysis showed that there are 16 genes that have a strong effect on protein levels.

"These results are important, as they show which variables are significant for variations in the measurable values," said Stefan Enroth, researcher at the Department of Immunology, Genetics, and Pathology at Uppsala University, in a statement. "If these factors are known, we have a greater possibility of seeing variations and we get clearer breakpoints between elevated values and normal values. By extension this may lead to the possibility of using more biomarkers clinically."

The researchers said that in some healthy individuals, genetics and lifestyle together account for more than 50 percent of variations in protein levels. In other words, the effective use of biomarkers depends on the consideration of both genetic and lifestyle factors.

Source: Enroth, et al. Strong effects of genetic and lifestyle factors on biomarker variation and use of personalized cutoffs. Nature Communications. 2014.