Monday, September 5, 2011

Testing Testosterone Part 3 Heatlhy Non-Obese Younger Men

Last November & December, I attempted to explain some of the nuances of testing one's testosterone level.  If you run most of your labs through Quest Diagnostics, which uses liquid chromatography tandem mass spectrometry (LC/MS/MS), you're used to seeing a normal reference range for total testosterone of 250-1100ng/dL for your 18-69yo males and 90-890ng/dL for your 70-89yo.

But what's normal?  Do you really want your testosterone level to match that of your overweight deconditioned neighbor?  Besides, what's good enough for your neighbor might not be good enough for you.  Case in point is our school grading system.  For the wanna-be valedictorian shooting for straight A's, even an above average B spells certain doom while that same B grade would be celebrated by those just happy to receive their GED or general education diploma.

Let me give you another example of the absurdity of this normal reference range.  Let's say that your male patient, who's a day short of his 70th birthday, shows up with a testosterone level of 1,000ng/dL which is within the normal reference range.  But then he comes in the very next day on his 70th birthday and again checks his total testosterone level.  The same level/number that was considered normal yesterday is now considered too much even though nothing's changed besides his age.

Therefore, I read with great interest a study published in last month's Journal of Clinical Endocrinology & Metabolism that concluded that the normal range for 456 healthy, non-obese men 19-40yo was 348.3ng/dL to 1,099.3ng/dL (with an average of 724ng/dL).  While the upper limit of normal is essentially spot on in comparison to the official reference range, the lower limit of normal is quite a bit higher (by 100ng/dL).  This could explain why many men who present w/hypogonadal signs & symptoms but a "normal" total testosterone respond so well to a trial of testosterone.  This is akin to the student who doesn't want to settle for a D grade but can't get help from the public school because he hasn't failed yet.

What's this mean for you and me?  Well, let's remember to treat the patient and help him reach his clinical goals.  And assuming that all else is equal, consider a therapeutic & diagnostic trial of testosterone supplementation in those w/signs & symptoms of hypogonadism with a total testosterone of 250-350ng/dL.