Performance enhancing drugs part 2

Arginine, ornithine, tryptophan and lysine can all increase endogenous production of growth hormone. As a result, athletes may consume these amino acid supplements to enhance performance.

The radioimmuno assay is the correct answer. There are multiple isoforms of human growth factor (hGH); however, rhGH contains only the 22 kDa isoform. Therefore, ratios of hGH can be measured to determine if exogenous is rhGH is being used. Serum level will measure both hGH and rhGH and will be of little use. A whole blood level is not necessary because hGH and rhGH do not distribute to the RBC compartment. Pituitary stimulation assay is not correct.

The mechanism of action of meldonium is that it inhibits carnitine transporter type 2. This has the effect of ultimately the effect improving energy metabolism during hypoxia. The other answers are incorrect.

Currently the standard is to test athlete’s urine with isoelectric focusing. Recombinant EPO and endogenous EPO have different patterns of glyosylation, which results in differing final resting positions when isoelectrically focused. The gel is the subject to an antibody assay that is specific for EPO. Samples with recombinant EPO will have a differing pattern of antibody staining. Blood samples do not need to be assayed to accurately screen for exogenous EPO use. Hematocrit > 50% for men and > 47% for women was used as a screening tool in the past; however, training at altitude can create a significant amount of false positives. There is no recombinant EPO specific rapid POC screen.

Epitestosterone differs from testosterone by the location of a hydroxyl group. It is not a metabolite of testosterone. The serum T/E ratio is about 30/1; however, the urinary T/E ratio is normally 1/30. A cutoff for the urinary T/E ratio of 4/1 has been used to screen for exogenous testosterone use. Although ethanol can increase urinary T/E, it has only been to do so to a T/E of 10/1. Many body builders use clomiphene to block the inhibitory effect of exogenous testosterone of LH and FSH secretion, thereby limiting testicular atrophy. Excessive grapefruit would likely not change the ratio because epitestosterone is not a metabolite of testosterone.