There are basically two different types of testosterone in your body that we need to assess to be able to diagnose you with low testosterone properly.
If you have already had some of these tests done by another doctor recently please let us know so we only check what’s needed.
Total vs Free Testosterone
Testosterone in your body is floating around in your blood, either freely or bound to a binding globulin. The majority of your testosterone, or total testosterone, is bound to a globulin, called sex hormone binding globulin (SHBG).
There are other elements in your blood that bind testosterone but none of them as much as SHBG. When SHBG binds testosterone it makes it inactive.
The remaining testosterone, that is not bound to SHBG, is the free testosterone. Free testosterone is the active portion of the total testosterone and in many ways more important than the total testosterone.
Some men, especially older men, have normal levels of total testosterone but low levels of free testosterone. Low free testosterone is low testosterone and can certainly cause symptoms of low testosterone.
Common symptoms of low testosterone include:
- Decreased motivation/drive
- Decreased mental clarity
- Increased body fat
- Decreased libido
We have found the most accurate way to assess free testosterone to be through a calculation. If you know your total testosterone and sex hormone binding globulin you can “plug” your numbers in here: Free Testosterone Calculator
Do your testosterone levels vary?
Testosterone levels can certainly vary from day to day. Also, testosterone levels are generally higher in the morning and then decline throughout the day.
In general, it is best to check your total and free testosterone levels in the morning before 10am on two separate days.
Many insurance companies require testosterone levels be checked in the early morning on two separate days in order to cover testosterone therapy.
SPECIAL Testosterone lab testing included with first visit for new patients.
What types of low testosterone are there?
There are basically two types of low testosterone:
- Primary Hypogonadism
- Secondary Hypogonadism
You can read a pretty good overview of the types of low testosterone and some potential causes here: What’s Causing My Low Testosterone?
Often times it is difficult to identify the specific cause of low testosterone. Some doctors may say your testosterone levels are low due to age but there is really no way to know for sure.
Luteinizing hormone (LH) is produced in the brain and travels through the blood until it reaches the testicles causing the testicles to produce testosterone.
LH can be measured in the blood. In fact, a number of signals are produced in the brain and travel throughout the body. These signals tell different parts of your body to produce hormones.
In some men, LH can be high and this is associated with primary hypogonadism. In primary hypogonadism, there is plenty of LH but the testicles are not responding properly. In some men there can be a failure of the testicles to function, causing almost no testosterone production.
In other cases, LH will be normal or low. Generally, if the testosterone is low and the LH level is normal we consider this inappropriately normal as we would expect a higher signal if the part of the brain that produces the signal was functioning optimally.
When the signal is low or inappropriately normal, this is considered secondary hypogonadism.
Some doctors may diagnose patients with mixed hypogonadism. In mixed hypogonadism there may be a combination of an inadequate signal or decreased signal production and a decrease in the ability of the testicles to produce testosterone.
Beyond Low Testosterone Labs
There are a few conditions that we try to rule out when diagnosing low testosterone:
- Sleep apnea
Most genetic causes of low testosterone are typically quite obvious as symptoms will develop during puberty (ie genitals not developing properly).
Hemochromatosis is a disorder of iron overload. It is usually hereditary but there are also other possible causes. Too much iron in the body can cause several health issues, one of which is low testosterone. It is important to identify the cause of iron overload but it is usually hereditary (inherited) and easily treated.
- How do you check for hemochromatosis?
- Measure iron levels in blood
Hyperprolactinemia is the elevation of a hormone called prolactin in the body. It is produced in the same area of the brain as the signal from the brain to the testicles, LH.
- How do you check for hyperprolactinemia?
- Measure prolactin levels in blood
Diabetes is becoming too common in the United States with about 1 in 3 men either being diabetic or about to become diabetic. Your primary care doctor should be checking you for diabetes every year with your annual exam.
- How do you check for diabetes?
- Hemoglobin A1C is a blood test that assesses your average blood sugar over the past few months and often is not checked with you annual exam.
- Fasting blood sugar levels
A recent study showed that men with low testosterone and untreated sleep apnea did not see a significant increase in their testosterone levels after being treated for sleep apnea.
If we suspect you have sleep apnea we may refer you for a sleep study or advise you discuss a sleep study with your primary care doctor.
If you have severe sleep apnea it is important to get treated for sleep apnea prior to starting testosterone replacement therapy (TRT) as TRT may worsen your sleep apnea.
Sleep apnea is easier today to treat than it was in the past. Most men can do their sleep study at home as well. There are a number of sleep medicine clinics in the Seattle area.
Low thyroid function can case similar symptoms to low testosterone, including fatigue and low mood. A simple blood test for something called thyroid stimulating hormone can help identify an obvious thyroid problem.
Other lab tests
We require that patients have had their PSA checked in the past year prior to start testosterone therapy and the other labs above are recommended as well. Most of our patients have had some of these labs done by their primary care doctor within the past year.
- What other lab tests should you consider prior to starting testosterone therapy?
- Prostate Specific Antigen (PSA) – helps assess prostate health
- AST & ALT – liver function tests
- Complete Blood Count (CBC) – helps check for infection and assess blood thickness
- Estradiol (estrogen) – get a baseline on your conversion of testosterone to estrogen
What if you’re diagnosed with low testosterone?
If you’re found to have low testosterone we will discuss your treatment options. Low testosterone therapy options may include testosterone injections, medications to increase your natural production of testosterone, and medications to reduce the conversion of testosterone to estrogen.
Also, it is always good to take a copy of your lab results to your primary care doctor and we’re happy to fax them a copy at your request.
If it looks like there is something we need to be concerned about we may refer you to a specialist. For example, if you’re snoring a lot and have never had a sleep study we may help you find a sleep study clinic in your area to get checked out.
Most patients doing weekly testosterone injections at home can expect to pay as little as $100 for a 3 month supply of medication.