C-reactive protein (CRP) is a very strong acute phase protein. During the acute phase of disease the CRP concentration can increase up to a thousand-fold. However, a higher CRP concentration is also observed during chronic stages of disease, for example in subjects with chronic bronchitis, periodontal disease or subjects with increased titers of Helicobacter pylori or Chlamydia pneumoniae. The concentration of CRP is also reported to be associated with age, sex, race, smoking, obesity, consumption of coffee and alcohol, stress, physical training, lipid levels, and blood pressure. Statins decrease the CRP concentration whereas estrogen increases it. With regard to most other drugs no consistent relationship has been reported.