Reference Intervals for Platelet Counts in the Elderly: Results from the Prospective SENIORLAB Study

Area of Science:

• Gerontology
• Hematology
• Clinical Chemistry

Background:

• Current interpretation of elderly platelet counts often relies on age- and sex-independent reference limits (RLs).
• This approach may lead to inaccurate assessments in older populations.

Purpose of the Study:

• To define and validate age- and sex-specific reference intervals (RIs) for platelet counts in individuals aged 60 years and older.
• To compare the diagnostic utility of these new RIs against traditional, non-specific RLs.

Main Methods:

• Prospective cohort study (SENIORLAB) of healthy Swiss individuals aged 60+.
• Exclusion of participants with factors affecting platelet counts.
• Validation using indirect statistical methods and a large population-based dataset from Liechtenstein.

Main Results:

• Defined age-specific 95% RIs for males (e.g., 150-300 × 10^9/L for 60-69 years) and a consolidated age-independent RI for females (165-355 × 10^9/L).
• Validated RIs using data from over 51,000 patients.
• Demonstrated that age- and sex-independent RIs result in imbalanced abnormal platelet count frequencies between sexes, which is corrected by specific RIs.

Conclusions:

• Females generally exhibit higher platelet counts than males.
• The lower limit of normal for platelet counts decreases with age in males.
• Recommends abandoning sex- and age-independent RLs for platelet count interpretation in the elderly.