Blood Protein Levels Shift Significantly from Childhood Through Early Adulthood

Blood protein levels undergo significant changes from childhood through early adulthood, with more than half of the proteins measured showing age-related shifts, according to a longitudinal study published in Nature Communications. The research, which followed 100 individuals from ages 4 to 24 years, found that protein levels are strongly influenced by both age and sex, particularly during puberty and the transition to adulthood.

The study analyzed plasma samples collected at four time points—ages 4, 8, 16, and 24—using Olink Explore HT technology to measure over 5,000 proteins. Of these, 3,509 were suitable for longitudinal analysis, and 54% were found to be associated with age. Researchers observed distinct protein trajectories, including sharp increases during adolescence (ages 8 to 16) followed by declines in early adulthood, as well as more gradual changes across the developmental period.

Age and Sex Drive Major Shifts in Blood Protein Profiles

The most pronounced changes in blood protein levels occurred between the ages of 8 and 16, a period encompassing puberty. During this window, many proteins increased sharply, only to decrease again by early adulthood. Other proteins showed steady increases or decreases from childhood into early adulthood.

Sex-related differences in protein levels were minimal in early childhood but became increasingly pronounced starting at age 16 and continuing through age 24. These differences were especially notable in proteins involved in growth, response to stimuli, and regulation of catabolic processes.

Implications for Pediatric Reference Values and Future Research

The findings challenge the use of adult reference values for interpreting blood protein levels in children, and adolescents. Since more than half of the tracked proteins change with age even during childhood, relying on adult norms could lead to misinterpretation of developmental or clinical data in younger populations.

According to Sophia Björkander, assistant professor and docent at the Department of Clinical Science and Education, Södersjukhuset, Karolinska Institutet, and one of the study’s lead authors, “Our study shows that reference values from adults cannot be used when interpreting protein levels in children and adolescents. Protein levels are strongly age-dependent even early in life.”

The researchers emphasize that this longitudinal protein profiling map serves as a valuable resource for understanding normal physiological development, identifying disease biomarkers, and improving the precision of pediatric diagnostics and treatment strategies.

Key Takeaways

• Over half of the 3,509 blood proteins analyzed change significantly with age from childhood to early adulthood.
• The most significant changes occur between ages 8 and 16, coinciding with puberty.
• Sex differences in protein levels develop into pronounced during adolescence and persist into early adulthood.
• Adult reference values are inadequate for assessing protein levels in children and adolescents.
• This study provides a critical reference for future research in developmental biology, biomarker discovery, and precision medicine.

By mapping how the blood proteome evolves across key developmental stages, this research advances our understanding of human maturation and lays the groundwork for more accurate, age- and sex-specific clinical applications in pediatric and adolescent health.