Is serum prostate-specific antigen level affected by fasting and nonfasting?

Abstract Objectives To determine whether the level of serum prostate-specific antigen (PSA) varies with fasting and nonfasting. Methods The study involved 80 male patients with normal digital rectal examination who were hospitalized for benign urologic problems. The patients with active urinary tract infection, urologic cancer, urethral catheterization, diabetes mellitus, or acute or chronic renal failure and those who had undergone urologic manipulations within the past 45 days were excluded from the study. All the patients were asked to fast between 12:00 am and 8:00 am . The next morning, 10-mL venous blood samples were obtained at 8:00 am . Then each patient was provided with breakfast, which was followed by additional serial venous serum sampling during the first and second hour. The patients ate lunch at 12:00 pm . The final venous serum sampling was conducted at 2:00 pm . The serum PSA levels were determined for all the serum samples. Results The mean patient age was 62.42 ± 8.75 years (range 46 to 82). The mean serum total PSA value at fasting and the first, second, and sixth hour was 2.78 ± 2.19, 2.7 ± 2.0, 2.7 ± 2.1, and 2.78 ± 2.10 ng/mL, respectively. In the comparisons of the fasting values and first, second, and sixth hour values and the values at each hour with those at the other hours, no significant differences were observed ( P >0.05). Conclusions According to our results, blood samples can be obtained for serum PSA measurement at any time of the day, regardless of whether the patient has fasted or not.