Metabolizing fat? Only educated people with medical or nutrition knowledge please... no negative comments?

Question

My brother used to be a hippie in high school, but he has pulled a complete 180 since college and is now in law school. He asked me for help for part of his research paper since I am a self proclaimed health nut, but I'm not actually sure how to answer his question. He is writing about drug courts and the testing for marijuana in urinalysis. He has gone through many of the options available that people have used to hide, mask or eliminate the metabolites in the urine, but he posed to me a tricky question. Since THC is stored in fat cells, would it be possible to provide a false negative on a test by either... eating a high fat diet before the test, or by starving oneself? It puzzled me because either seems plausible, by either providing the body with quick fat to metabolize thereby maintaining body fat stores, or by keeping the metabolism slowed. Would body fat excrete the metabolites if the body had an overload of fat to digest? Any articles or journal links appreciated!

Answer 1

According to Tietz  Fundamentals of Clinical Chemistry, "Marijuana is metabolized extensively to a large number of compounds, most of which are inactive. The principal urinary metabolite is 11-nor-(delta9-tetrahydrocannabinol-9-ca... acid (THC-COOH) and its glucuronide conjugate.

(What the glucuronide conjugate means is the portion of the compound that is attached to glucuronic acid, a substance that increases water solubility, and as a result allows it to be excreted in urine.)

"THC is absorbed rapidly through the lungs and reaches peak blood concentration within minutes; thereafter, blood concentration rapidly declines to about 10% of peak levels within 1-2 hours. This rapid decline in THC concentration is a result if ease of distribution to tissues such as brain, fat, and muscle. The rapid tissue distribution phase, a consequence of the lipophilic [(non-polar, water insoluble, and fat-loving)] nature of THC, is followed by a slow redistribution of THC back into the bloodstream and subsequent hepatic [liver] elimination."

The initial screening test for marijuana is most often immunoassay. Immunoassays designed to screen urine samples for marijuana use measure THC-COOH and other THC metabolites...., calibrated with THC-COOH, but because of cross reactivity with many other THC metabolites, quantitive results based on them are 1.5 to 8 times greater than actual concentration of THC-COOH as determined by GC/MS. [That is gas chromatography/mass spectometry, a much more sensitive and accurate detection technique].

"Because o the slow release of THC from tissue storage sites, urine may test positive for THC metabolites (>20ng/mL THC-COOH equivalents) for 2 to 5 days after the last marijuana use by infrequent smokers...

Due to fluctuations in fluid excretion, the concentration of THC metabolites in urine may vary

between positive and negative values when it is measured sequentially after several days of abstinence. In this case, an increase in metabolite concentration could imply falsely the reuse of marijuana.

Therefore to monitor abstinence properly the concentraqtion of THC-COOH should be expressed per mg of creatinine. [Creatinine is a substance produced by creatine breakdown, that is a good indicator of overall kidney output because it is filtered freely at the glomeruli, and it is not reabsorbed in the tubules. All of the clearance tests, are good indicators of kidney function with adequate urine formation.]

That is a good question! By that reasoning anything that prevented the breakdown of fatty tissues where the THC was deposited would result in lower levels of the metabolite in blood and then in urine. Possibly that has something to do with all that discussion of the fluctuating levels of THC in urine.

I don't think eating a lot of fatty foods would be as effective as the administering of insulin since insulin helps glucose enter the cells to be used, but also initiates lipogenesis, or the metabolic cycle during which fat is generated from dietary excesses. I also think that the process of conjugating THC to glucuronic acid (in the liver) has a very large infuence since the THC alone is not very water soluble and therefore cannot enter urine to be excreted until it is made more water soluble.  

I hope I said something that was helpful. parts in [  ] s are my own interpretations and within "   " came straight from my Clinical Chemistry text. Good luck finding out more. It may be helpful to specifically research "Drugs of abuse testing", clinical toxicology, etc.