Like any substance, there are a number of factors that could influence how long Mitragynine remain in your system.
Age. Older Kratom users tend to have a longer half-life than the younger users. This is the same with most substances. It is because elderly people have less efficient renal function than the younger adults. Age-related diseases and the use of maintenance medications also play a role. It is safe to assume that if you are older, particularly over the age of 65, Kratom will have longer elimination half-life than it would in younger user.
Genetics. Certain enzymes and genetic markers may play a role in the duration at which Kratom is eliminated from the body.
Body Fat. A person’s percentage of body fat may play a role too. Mitragynine is highly fat-soluble, meaning that if you have a high body fat percentage, you’ll likely retain Kratom metabolites much longer than a person with lower body fat. Those with less fat will be able to remove Kratom quickly since it would not be stored.
Water and food intake. Taking Kratom with a high-fat meal could lead to faster absorption of Mitragynine. This could speed up the duration of the substance to reach peak concentration level. In addition, if you are well-hydrated, it may play a role on how long it will take for the substance to be excreted in the urine.
Other factors or variables that may influence Kratom’s elimination half-life includes your urinary pH, renal function, and metabolic rate. These are not factors that only applies to Kratom. This is the same with any substances.
The duration of its elimination half-life can also vary on the type of Kratom you take and the specific variety of plant that the leaves were harvested. Research suggests that Kratom from Southeast Asia tend to contain higher levels of the alkaloid Mitragynine. On one hand, those that are grown in locations outside Southeast Asia or in greenhouses tend to have modest or insignificant levels of Mitragynine. In some occasions, Mitragynine may not be present at all.
It is assumed that Kratom leaves with higher levels of Mitragynine will have a more potent effect and that Mitragynine, along with its metabolites, will stay in the system for longer periods. Leaves with minimal Mitragynine may contain higher amounts of other alkaloids, however, they are unlikely to be detected on a drug screening.