Re: I always hear people on here saying "even at 21 your still to young, your testos
borris said:
And yes these are BROAD AND CREDIBLE facts of how much your natural testosterone drops as you get older. These are in every textbook bio classes get in college, these are on anatomy sites, these FACTS are in every site you go to if you want to learn how much your testosterone drops as you get older. You don't need "lab rats" or "test subjects" to take a simple blood sample and on a national level make a credible average percent of how much people's testosterone drops, lol, people get their testosterone checked ALL THE TIME. Doctors know what the average % of natural testosterone by age is in the back of their head.. These are facts that have been attributed by millions upon millions of men getting their bloodwork done, it's not 50 random male "test subjects" or "lab studies"
It is not as simple as that Borris.
Also note the HUGE reference ranges. A lot of other analytes in the body are held within tight control and have a very small reference range, things like sodium, potassium and calcium.
These reference ranges are still adjusted by each lab to relate to the local population, as things do vary, and it is not just the people.
Testosterone is a notoriously difficult hormone to measure and the current immunoassays, which has allowed for MORE to be tested in a more rapid fashion, and also cheaper, is still not all that great.
A little blurb from a lecture I went to:
ANDROGEN ASSAYS
Wheeler, M.
Department of Chemical Pathology, St Thomas' Hospital, Guy's and St Thomas' NHS Foundation Trust, London, SE1 7EH
In 2003, in an editorial in clinical chemistry, Herold and Fitzgerald suggested that testosterone assays could be considered random number generators.
Admittedly they were considering the use of the assays in the investigation of female pathologies, but are the assays any better at the higher concentration present in men?
Questions that one might ask include:
1. Do testosterone assays have adequate precision and specificity to give the clinician confidence in the results they receive for their patients.
2. How good is the agreement between different assays? If a patient's sample is sent to a laboratory using method A will there be a similar result from another laboratory using method 8.
3. What factors influence the result in terms of a) drugs b) concentration of proteins and other constituents in the sample c) what sample tube is used and d) when the sample is taken.
4. Should we measuring free testosterone as well as, or instead of, testosterone? If so is an androgen index (testosterone/SHBG) as good as free testosterone determined in another way.
This talk will address these questions.
Recent data from an evaluation of automated direct testosterone methods, carried out for the Medical and Health products Regulatory Agency in the UK gives rise to much concern.
In the female testosterone range, not only was there a two-fold difference between some methods but there could also be a two-fold difference in the results by users of the same method.
Even at male testosterone concentrations the precision of some methods was poor with a 3.5 mmol/L difference across the methods.
Results are affected by the concentration of sex hormone binding globulin with the recovery being higher from male serum. We are very much in the era of the black box, the technologist being unable to modify the assay.
It is important that each method is evaluated before it is introduced in the laboratory. Evaluation of an oestradiol method from one manufacture showed that the matrix of the calibrator was totally inappropriate for human serum.
Technologists have been concerned about the possibility that the separating gel present in SST blood tubes might affect results by either absorbing small molecules or contributing interfering substances into the serum. There are few well conducted studies and some reports are conflicting. Recently it has been shown that some Becton Dickinson tubes affect some assays, including a testosterone assay.
The clinician can contribute to the confusion by not appreciating the very significant circadian rhythm of testosterone concentration present in young and older men. So with all these limitations of total testosterone assays, would free testosterone be a more accurate indicator of androgen status.
Our data suggests it is not a good indicator in men with a large overlap between normal men with primary hypogonadism. If free testosterone concentration is determined, Vermeulen suggests that a result that is mathematically calculated from the testosterone and SHBG is better than an androgen index.
Overall data suggests testosterone results should be interpreted with much caution.
Perhaps using the patient as a bioassay in as good as current direct immunoassays. The introduction of methods using tandem mass spectrometry may provide testosterone assays that are specific and free from interference.
However both the instruments and the engineering support has to undergo a lot of improvement before these become suitable for the routine measurement of large numbers of samples.
http://www.andropause.org.uk
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