PSA Doubling Time Calculator
Calculate PSA doubling time to assess prostate cancer progression and treatment response
Calculate PSA Doubling Time
Earlier PSA Test
Recent PSA Test
PSA Doubling Time Results
Enter two PSA test results with dates to calculate doubling time
⚠️ Medical Disclaimer: This calculator is for educational purposes only and should not replace professional medical advice. PSA doubling time should be interpreted by a qualified healthcare provider in the context of clinical findings and other diagnostic tests.
Example Calculation
Clinical Scenario
Patient: 68-year-old male post-prostatectomy
First PSA test (Jan 1, 2024): 0.5 ng/mL
Second PSA test (July 1, 2024): 1.0 ng/mL
Time difference: 6 months
Calculation
Doubling Time = (6 months × ln(2)) / ln(1.0/0.5)
Doubling Time = (6 × 0.693) / ln(2)
Doubling Time = 4.16 / 0.693
Doubling Time = 6.0 months
Result: At threshold value - requires close monitoring
PSA Reference Ranges
General Population
- • Normal PSA: < 4.0 ng/mL
- • Borderline: 4.0-10.0 ng/mL
- • Elevated: > 10.0 ng/mL
Post-Prostatectomy
- • Undetectable: < 0.1 ng/mL
- • Biochemical recurrence: > 0.2 ng/mL
Doubling Time Interpretation
< 6 months: Aggressive
6-12 months: Moderate
> 12 months: Slow
Clinical Tips
Use most recent two PSA tests for accuracy
Minimum 3-month interval between tests recommended
Consider clinical context and treatment history
Understanding PSA Doubling Time
What is PSA Doubling Time?
PSA doubling time (PSADT) is the time it takes for prostate-specific antigen levels to double. It's a crucial marker for assessing prostate cancer progression, treatment response, and prognosis.
Clinical Applications
- •Monitoring biochemical recurrence after treatment
- •Guiding treatment decisions and intensity
- •Predicting overall survival and cancer-specific mortality
- •Active surveillance decision-making
Mathematical Formula
PSADT = (t × ln(2)) / ln(PSA₂/PSA₁)
- t: Time between measurements
- PSA₁: Earlier PSA value
- PSA₂: Later PSA value
- ln: Natural logarithm
Additional Metrics
PSA Velocity
Rate of PSA change over time (ng/mL per month or year). Higher velocity indicates more aggressive disease.
PSA Slope
Natural logarithmic representation of PSA growth rate. Steeper slopes indicate faster progression.
Clinical Context and Limitations
Important Considerations
- • Requires at least two PSA measurements
- • More accurate with multiple time points
- • Consider PSA assay variations and lab differences
- • Account for medications affecting PSA levels
Treatment Implications
- • Fast doubling (<6 months): Consider aggressive therapy
- • Slow doubling (>12 months): May allow active surveillance
- • Combine with other prognostic factors
- • Regular monitoring regardless of doubling time