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THC/Creatinine Ratio Formula:
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The THC/Creatinine ratio is a calculation used to normalize THC levels in urine tests by accounting for urine concentration. This helps provide a more accurate assessment of THC exposure regardless of hydration status.
The calculator uses the simple ratio formula:
Where:
Explanation: The ratio accounts for urine dilution by normalizing THC levels against creatinine, which is excreted at a relatively constant rate.
Details: This ratio is particularly important in drug testing to distinguish between dilute urine samples and actual low THC levels. It provides a more reliable indicator of recent cannabis use than THC concentration alone.
Tips: Enter THC concentration in ng/mL and creatinine concentration in mg/dL. Both values must be greater than zero for accurate calculation.
Q1: Why use THC/creatinine ratio instead of just THC concentration?
A: The ratio accounts for urine dilution, providing a more accurate assessment of THC exposure that isn't affected by hydration status.
Q2: What is a typical cutoff value for positive tests?
A: Cutoff values vary by testing program, but common thresholds range from 15-50 ng/mg THC/creatinine ratio for workplace drug testing.
Q3: How does creatinine correction improve accuracy?
A: Creatinine is excreted at a relatively constant rate, so normalizing THC levels against creatinine compensates for variations in urine concentration.
Q4: Are there limitations to this ratio?
A: The ratio may be less accurate in individuals with kidney dysfunction or unusually high/low muscle mass, as these affect creatinine production.
Q5: Can this ratio determine time since last use?
A: While higher ratios generally indicate more recent use, many factors influence THC metabolism, making precise timing difficult from a single measurement.