What does testosterone do?
Testosterone (T) is hormone produced in the testes of men and ovaries of women. It’s connected to sexual development, muscle building, fat loss, some aspects of cognition, and hair loss.
- Your total T levels might not indicate the whole story of how testosterone is functioning in your body.
Total T can be broken down into 3 categories:
- Tightly bound T: This is the majority of the T in your body (about 2/3), and its bound to SHBG (sex-hormone binding globulin). Because T is a steroid hormone, it’s cannot easily float around the water-soluble blood environment. Having the T bound to a protein helps its solubility in water. Just because it’s tightly bound, doesn’t mean the cell can’t uptake the entire SHBG-T complex into the cell for use (via endocytosis).
- Loosely bound T: About 1/3 of the T in your body is loosely bound to albumin. If the bond breaks, free T is now floating around.
- Free T: a very small percentage of the total floats around freely. Your body can readily use it, and it’s converted to DHT (dihydrotestosterone) by the enzyme 5-alpha-reductase, which is a very potent androgen.
It’s important to note that not all free T gets converted into DHT, and not all bound T is unusable by the body.
Why should you assess your levels?
It’s important to realize that the types of assessment out there are varied – with accuracy being the most important piece. More than likely, if you get your levels tested randomly, it will be an inaccurate measurement as well as unnecessary. Testosterone levels have a LARGE range of “normal”, and just because it’s in the lower part of the normal range, doesn’t mean you have abnormal levels or should be prescribed testosterone.
- Another important thing to think about is that once exogenous T is introduced to the body, it’s basically doping. Endogenous production of T is completely different, and your unique range of “normal T” will be different than other people, so it’s important not to compare.
As mentioned above, free T might be more available to use, but it doesn’t mean your body will use it.
Some reasons you might want to get your T checked –
- Delayed puberty, depression, erectile dysfunction, excess breast tissue, hair loss, increased body fat, loss of muscle mass, low sperm count, poor bone health, stunted growth, and issues with fertility and/or pituitary gland
- Medical conditions like hypogonadism
- Causes of hypogonadism are age, cancer, HIV, disorders of the testicles, Kallmann syndrome (loss of smell and delayed/absent puberty), hypothalamus-pituitary-axis disorders, infections, and liver/kidney diseases
- Deficiency in enzyme 5-alpha-reductase (the enzyme that produces DHT)
- Taking certain drugs that decrease T levels: **don’t stop treatment without physician approval, but consider having a conversation if you’re concerned**
- Antiandrogens, chemotherapy, chronic anabolic steroid use, glucocorticoids, ketoconazole, LHRH analogs or GnRH agonists, opioids, radiation therapy, SSRI, suramin
***If you have symptoms listed above, or family history concerns, it might be useful to get your T levels checked every 6-12 months.
General specific situations to get your levels checked could be abnormal SHBG concentration, someone being evaluated for hypogonadism and overweight, or in older males.
How are testosterone levels assessed?
T levels vary throughout the day. Also, transiently, exercise causes cortisol to increase and testosterone to decrease. If they are suspected of being low, the best time to measure is from 8 am to 10 am, ideally. If you are taking opioids, glucocorticoids, or have an acute/subacute illness, your T levels will be low automatically and it won’t be an accurate measurement. Most importantly, consult with a physician before you seek out the test on your own.
Testing is extremely varied. Optimally, total testosterone should be measured using an assay certified as reliable and accurate. Additionally, if a measurement was taken in the morning and labeled as low, the test needs to be repeated at least twice more to be an official diagnosis. The test should also be completed in a fasted state.
- Measurement of free T is recommended usually when the total T concentration is lower limit of normal range (300 to 900 ng/dL for most labs, but 264 to 916 ng/dL is also used).
What can be done to prevent decrease of T production or support healthy levels?
Endogenous testosterone levels (the levels that your body makes), function differently than exogenous T introduced. The body will response to the exogenous T more readily, hence why doping restrictions are present. Having a level of T within the normal range will benefit your body health overall, and it’s better to focus on the habits that will support optimal T levels than the actual number of T in ng/dL or how much free/loosely bound T you have.
These are things you can do to support optimal levels of T:
- Vitamin D – check your levels to see if you need to supplement!
- Healthy fats (plant oils) – it’s important to get a minimum of 20% of calories from healthy fat
- Sleep – 8-9 hours is ideal (really, you can’t sustain weight loss or proper recovery with less than 7 hours)
- Magnesium – all we know is that there is an associated increase of testosterone with magnesium supplementation and exercise (3), additionally, magnesium might support SHBG levels –> 320-360 mg per day for men & 400-420 mg per day for women
- Zinc – there is no research that proves zinc supplementation increases T levels, but there have been studies demonstrating a correlation (while correlation does not equal causation, it doesn’t hurt to ensure you’re reaching adequate zinc consumption each day) –> 11 mg per day for men and 8 mg per day for women
- Monitor your weight – a large amount of body fat is correlated to low T, and adipose tissue located viscerally (around the midsection) can function like an endocrine organ, meaning it takes on the role of the pituitary gland
Overall, you can’t compare levels within the large normal range. Metabolically, a low value that is within normal range is still normal, and a high value within normal doesn’t necessarily mean anything different. Situationally, if someone normally has high levels, then they plummet versus someone who has always had moderately low levels within the normal range, it’s still a completely different situation! One test won’t determine true levels of T, and it’s important to address the things above before considering you have abnormal T levels.
| (1) | Testosterone Supplements — Research on Benefits, Side Effects, and Interactions | Examine.com |
| (2) | UpToDate – a subscription that compiles Wolters Kluwer Health Publications to summarize evidence-based clinical recommendations |
| (3) | J Pharm Biomed Anal. 2009 Feb 20;49(2):175-80. doi: 10.1016/j.jpba.2008.10.041. Epub 2008 Nov 5 From <https://pubmed.ncbi.nlm.nih.gov/19095394/> |
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