Age-related changes in laboratory test results. Clinical implications

Area of Science:

• Clinical Laboratory Science
• Geriatric Medicine
• Biostatistics

Background:

• Age-related changes in clinical laboratory assays are significant, particularly in early life, adolescence, old age, and post-menopause.
• Limited data exist for elderly populations despite their substantial healthcare utilization.
• Accurate reference values are crucial for diagnosis and initiating drug therapy, especially when prior results are unavailable.

Purpose of the Study:

• To address the lack of comprehensive data on age-related changes in clinical laboratory values for the elderly.
• To evaluate the utility of conventional adult reference values for the very elderly.
• To explore the application of biological variation data for interpreting serial results in elderly individuals.

Main Methods:

• Analysis of age-related changes in various clinical laboratory quantities.
• Comparison of reference intervals in elderly populations versus younger adults.
• Utilizing databases on biological variation and analytical imprecision to calculate critical differences for serial results.

Main Results:

• Reference intervals for the elderly can be wider than for younger adults, potentially due to the inclusion of unhealthy individuals in reference groups.
• Individual biological variation is significant, meaning serial results may fall within reference limits yet be unusual for the individual.
• Within-subject biological variation in healthy elderly individuals is comparable to that in younger adults.

Conclusions:

• Conventional adult reference values may be appropriate for the very elderly, with caution regarding wider intervals.
• Clinical laboratory tests may have limitations in detecting early or latent disease due to individual variation within reference limits.
• Calculating critical differences based on biological variation is valuable for monitoring therapeutic effects in elderly patients.