Factors That Affect How Long Meth Remains Detectable
The time for which meth can be detected in your body depends on the metabolism rate of your body. There are a number of factors that influence on how long meth stays in your system.
These factors include, but are not limited to, the frequency with which you take meth, the kind of test that you use, your previous dosage, and how well your liver and kidneys function.
When meth is consumed, immediately starts metabolizing the drug while it is transported through the bloodstream. The body first changes the meth to amphetamine which provides the feeling of euphoria.
It is then broken down and digested by the kidneys and the liver. However, only half of the amount is metabolized, the rest of the excreted through urinary excretion only a few hours after its consumption.
Source – lifehack.org