Platelet counts differ by sex, ethnicity, and age in the United States

Ann Epidemiol. 2006 Feb;16(2):123-30. doi: 10.1016/j.annepidem.2005.06.052. Epub 2005 Oct 24.


Purpose: The aim of the study is to show that differences in platelet counts by ethnicity, sex, and age are not explained by environmental factors.

Methods: This is a cross-sectional population-based study of participants in the Third National Health and Nutrition Examination Survey. Our analytic sample included 12,142 participants, of whom 65% were women, 27% were non-Hispanic blacks, and 27% were Mexican Americans. We report weighted geometric mean platelet counts stratified by ethnicity, sex, and age and controlled for indicators of nutritional deficiencies and inflammation.

Results: The lowest mean platelet counts were in whites (260x10(3)/microL; 95% confidence interval [CI], 256-264), and the highest were in non-Hispanic blacks (281x10(3)/microL [95% CI, 276-286]). Older men and women of each ethnicity consistently had lower platelet counts than young adults; 60- to 69-year-olds had mean counts 7x10(3)/microL lower (p<0.001) and 70- to 90-year-olds had counts 18x10(3)/microL lower (p<0.001). Even controlling for iron deficiency, women had higher platelet counts than men (275x10(3)/microL; 95% CI, 271-279) versus 256x10(3)/microL (95% CI, 251-260; p<0.001).

Conclusions: Platelet count differences by sex, ethnicity, and age are not explained by environmental covariates known to influence platelet count.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Adult
  • African Continental Ancestry Group
  • Age Factors
  • Aged
  • Aged, 80 and over
  • Aging / blood
  • Blood Platelets*
  • Cross-Sectional Studies
  • Ethnic Groups*
  • European Continental Ancestry Group
  • Female
  • Humans
  • Inflammation / blood*
  • Inflammation / epidemiology
  • Inflammation / ethnology
  • Male
  • Mexican Americans
  • Middle Aged
  • Nutrition Disorders / blood*
  • Nutrition Disorders / epidemiology
  • Nutrition Disorders / ethnology
  • Nutrition Surveys
  • Platelet Count / methods*
  • Reference Values
  • Sex Characteristics
  • United States / epidemiology