OBJECTIVES: Thrombocytopenia, or low blood platelet count, is associated with disease progression and treatment for several chronic conditions, including liver disease, cancer, and HIV.  Yet, little information describing the impact of thrombocytopenia on patients is available.  This study compared indicators of health and functional status among individuals with and without thrombocytopenia. METHODS: 1999-2008 National Health and Nutrition Examination Survey (NHANES) data were used to identify individuals aged ≥20 years with normal and low platelets, using a threshold of 150x109/L.  Indicators of health and/or functional status included self-reported general health [1-5 scale, 1=excellent], number of health care visits and overnight hospital stays, days physical health was not good, inactive days due to physical health, and work limitations.  Weighted means and frequencies were summarized and compared using paired t-tests and chi-squared tests, respectively. RESULTS: 22,959/25,772 participants aged ≥20 years had information on platelets.  Of these, 526 (1.9%) had low platelets at the time of examination.  Individuals with thrombocytopenia were older (51.7 vs 37.2 years) and more likely to be male (67.7% vs 48.6%), infected with hepatitis C (7.4% vs 1.4%), and ever diagnosed with cancer (14.2% vs 8.0%) or a liver condition (12.3% vs 3.1%), p<.05 for all.  Fewer participants with thrombocytopenia reported excellent health compared to those with normal platelets (12.5% vs 16.5%, p<.0001).  Participants with thrombocytopenia reported more health care provider visits (2.35 vs 2.02, p<.0001) and were more likely to report an overnight hospital stay (0.19% vs 0.11%, p<.001).  Participants with thrombocytopenia had more inactive days due to physical health and were more likely to face work limitations (p<.01 for all). CONCLUSIONS: Thrombocytopenia is associated with limitations on functional status and increased health care utilization, some of which may be related to patients’ underlying health conditions.  Further study is needed to determine the incremental impact of thrombocytopenia.