Fasting is NOT Required for PSA or hsCRP Blood Tests
You do not need to fast for either PSA or hsCRP blood tests—both can be drawn at any time of day regardless of fasting status.
PSA Testing - No Fasting Needed
The evidence clearly demonstrates that fasting has no clinically meaningful effect on PSA levels:
A prospective study of 80 patients measured PSA at fasting baseline and serially at 1,2, and 6 hours after eating, finding no significant differences at any time point (P > 0.05) 1. Blood samples can be obtained for PSA measurement at any time of day, regardless of fasting status.
A large population study of 157,276 men confirmed these findings using dynamic mathematical modeling, concluding that any statistically detectable relationship between fasting time and PSA has minimal clinical impact on result interpretation 2.
The major guidelines for PSA testing make no mention of fasting requirements. The 2024 EAU guidelines emphasize that PSA should be confirmed "under standardised conditions (ie, no ejaculation, manipulations, or urinary tract infections) in the same laboratory" but do not require fasting 3.
hsCRP Testing - No Fasting Needed
The 2003 CDC/AHA guideline explicitly states that hsCRP should be measured "fasting or nonfasting" 4. The recommendation specifies:
- Two assays, averaged and optimally 2 weeks apart, provide a more stable estimate
- The person should be metabolically stable without obvious inflammatory or infectious conditions
- Fasting status is not a requirement
Important Caveats for Both Tests
For PSA:
- Avoid ejaculation, urinary tract manipulations, or active UTI before testing
- Confirm elevated results after a few weeks in the same laboratory
- DRE and other prostate manipulations should be avoided before testing
For hsCRP:
- If level >10 mg/L, search for obvious infection/inflammation and repeat in 2 weeks
- Patient should be metabolically stable without acute illness
- Two measurements 2 weeks apart provide better risk stratification than a single value