How long does marijuana thc-cooh stay readable in a urin sample?can the ng/ml level drop after 10 days

Depends on usage: Theoretically thc and its metabolites can be detected in a urine sample for up to four weeks after cessation of use. Specificity is set at 50 ng/ml. Anything higher is called positive. Not likely to see a significant drop before that time. Urine drug tests are not usually quantitative for thc, therefore, its reported positive if level is above 50ng/ml.

The problem with THC: This drug attaches to fat cells in your body and only starts to leave your body over time. (and with abstinence) Heavy users can be leaking the drug back into their blood & pee a month after they quit. A single brief cigarette once can leave your system in a week or less.