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The Critical Role of Lab Testing in Testosterone Replacement Therapy

which lab values should be monitored when using some testosterone therapy products

Which Lab Values Should be Monitored When Using Some Testosterone Therapy Products?

If you’re a man over 30, you may have noticed some unwelcome changes recently – feeling worn out, loss of muscle tone, diminished sex drive, erectile dysfunction, and just an overall lack of energy and zest for life. This could be due to declining testosterone levels, a condition known as hypogonadism or testosterone deficiency syndrome that affects millions of men as they age.

The good news is, with testosterone replacement therapy (TRT) under careful medical supervision, you may be able to get your groove back in the bedroom, the gym, and everywhere in between. But critical to the success and safety of TRT is close monitoring through laboratory testing before, during, and throughout your treatment regimen.

Understanding the lab tests your physician will order, what they mean, and how they guide your personalized therapy can help you be an informed and empowered patient. Monitoring key health markers ensures you receive the maximum benefits from TRT while avoiding potential adverse reactions or cardiovascular events. Let’s explore the intricacies of lab testing for testosterone replacement and how it can help you reclaim your health, vitality and quality of life.

Why Monitor Lab Values with Testosterone Therapy?

Testosterone levels naturally decline in men by about 1% per year after age 30, leading to age-related low testosterone or androgen deficiency syndromes. But sometimes testosterone drops abnormally low, leading to distressing sexual symptoms like erectile dysfunction and low libido as well as loss of muscle mass, fatigue, depression, and lack of motivation.

The diagnosis of hypogonadism is made based on both lab testing and clinical assessment of symptoms. Once low T is identified, TRT aims to bring testosterone levels back up to optimal levels and alleviate these symptoms through testosterone replacement therapies like testosterone gel, injections, or pellets.

But testosterone therapy involves much more than simply “topping off the tank.” Careful lab monitoring is crucial for several reasons:

Simply put, lab testing allows for a more precise, personalized and safe testosterone replacement regimen. Monitoring key health markers at regular intervals helps ensure you get enough testosterone to relieve symptoms without going overboard and incurring risks. Let’s look at exactly what lab tests your physician will order.

Key Lab Tests to Monitor on Testosterone Replacement Therapy

1. Total Testosterone

Measuring total testosterone levels in the blood is critical both before starting TRT to confirm hypogonadism and repeatedly during treatment to assess the adequacy of testosterone levels.

Normal total testosterone levels generally range from 300 to 1,000 ng/dL for adult males. Your physician will look for a total testosterone below 300 ng/dL on two separate mornings when diagnosing hypogonadism. On TRT, total testosterone should be restored to mid-normal, between 400-700 ng/dL, where most men feel their best.

Levels above or below this target testosterone range may require adjusting the dosage or frequency of your testosterone therapy. Your total testosterone will be checked within one to three months after initiating or changing therapy and every six to twelve months thereafter. Test first thing in the morning when levels peak.

2. Free and Bioavailable Testosterone

About 60% of circulating testosterone is bound to sex hormone binding globulin (SHBG). The remaining 40% is either “free” or loosely bound to albumin as “bioavailable” testosterone. This free and bioavailable portion represents the testosterone immediately available for use by your tissues and correlates better with symptoms.

While regular total testosterone testing is sufficient for most men on TRT, measuring free or bioavailable testosterone can provide additional useful information in certain situations such as:

  • Suspected hypogonadism with normal total testosterone
  • Persistent symptoms despite normal total testosterone on TRT
  • Conditions that alter SHBG levels like obesity, diabetes, or use of some medications

Aim for mid-normal free testosterone levels of 50-130 pg/mL. Optimal bioavailable testosterone is generally 150-350 ng/dL, though assays vary.

3. Complete Blood Count

A complete blood count (CBC) measures your levels of red blood cells, white blood cells, and platelets. Of particular interest when monitoring TRT is your hematocrit and hemoglobin level to gauge red blood cell production.

Testosterone stimulates erythropoiesis, which can elevate hematocrit and hemoglobin. If the levels rise too high on TRT, it puts you at risk for viscosity-related conditions like stroke, heart attack and pulmonary embolism. That’s why it’s critical to check a CBC soon after starting TRT and at regular 3-6 month intervals.

Notify your provider if your hematocrit goes above 54% or hemoglobin rises over 17.5 g/dL. Dose adjustments or temporary discontinuation may be required to restore safe levels and avoid complications like polycythemia.

4. Prostate-Specific Antigen (PSA)

Produced by prostate cells, PSA levels help assess prostate health, enlargement and cancer risk. Testosterone therapy can theoretically increase prostate cancer risk by stimulating prostate growth. Checking a PSA test establishes your baseline levels before starting TRT.

Your physician will monitor your PSA at least annually and likely every 6 months while on testosterone therapy, with ongoing prostate cancer screening for highest safety. Rapid rise, levels over 4 ng/mL or concerning symptoms warrant closer monitoring and discussion of prostate health.

5. Lipid Profile

A lipid panel examines your levels of total cholesterol, LDL “bad” cholesterol, HDL “good” cholesterol and triglycerides. Oral testosterone formulations can adversely impact cholesterol levels and cardiovascular events. Thus, a baseline lipid profile is recommended.

Monitoring lipid levels every 6-12 months on TRT allows your physician to identify concerning changes and intervene with lifestyle modifications or cholesterol medication if indicated. The goal is to keep your cardiovascular disease risk as low as possible.

6. Liver Function Tests

Testosterone, whether endogenously produced or given therapeutically, is metabolized extensively in the liver. Liver function tests (LFTs) including enzymes like AST and ALT assess potential liver toxicity.

LFTs establish baseline status and subsequently identify elevations signaling possible liver injury. Mild fluctuations are expected, but notify your provider if liver enzymes rise 2-3 times the upper limit of normal. LFT monitoring every 6-12 months is prudent.

7. Estrogen (Estradiol)

Some testosterone converts (“aromatizes”) into estradiol, the primary estrogen. Deficiency in men can cause sexual dysfunction and bone loss; excess increases risk for enlarged prostate and heart disease.

Monitoring estradiol levels can reveal improperly balanced testosterone dosing allowing for adjustments. Target levels are generally 15-40 pg/mL. Estradiol testing also provides additional data regarding hypogonadism.


The pituitary hormones LH and FSH regulate testosterone production. Low levels help distinguish primary hypogonadism (testicular failure) from secondary hypogonadism (pituitary/hypothalamic dysfunction) which guides treatment.

In primary hypogonadism, TRT aims to replace testosterone directly. For secondary hypogonadism, addressing the underlying cause like a pituitary tumor may restore natural production so testing for these forms of hypogonadism is useful.

Additional Tests

Your physician may order other hormone and metabolic tests at their discretion based on your health history, comorbid conditions, risk factors and concerns. These could include prolactin, cortisol, thyroid hormone, HbA1c, vitamin D, and metabolic panels assessing kidney function, electrolytes, and blood sugar control.

When to Conduct Testing for Testosterone Replacement Therapy

Careful timing of lab test orders allows efficient monitoring of your TRT at critical junctures. Prior to starting, baseline tests are needed to confirm low testosterone and establish your status for comparison.

Testosterone, estradiol, CBC, and PSA should be checked no sooner than 6 weeks after starting or changing therapy when levels stabilize. Ongoing testing at regular intervals allows assessment of treatment efficacy and safety:

TestosteroneEvery 3-6 months
Hematocrit/HemoglobinEvery 3-6 months
PSAAnnually or every 6 months
Lipids, LFTsEvery 6-12 months
Metabolic PanelsAnnually

Labs help determine if dose adjustments are working through post-adjustment testing. New or worsening symptoms warrant prompt testing. More frequent monitoring of history of polycythemia, prostate disorders, liver disease, etc.

Interpreting and Responding to Your Test Results

When your lab results come back, your physician will review them with you to assess:

AssessmentAction Step
Are testosterone levels optimal now?If not, dosage adjustments may be advised.
Has hematocrit remained below 54%?High hematocrit may prompt reducing testosterone dosage and rechecking levels.
Has PSA substantially increased?Concerning rises may warrant closer monitoring, prostate exam, or referral to a urologist.
How are cholesterol and triglycerides trending?Worsening lipids may require adding cholesterol medication or lifestyle changes.
Are liver enzymes stable or elevated?High enzymes may reflect need for dose change or workup for other causes.
Are estradiol levels balanced?High or low estradiol can indicate need for dosage tweaking.
Have sexual function, energy, and other hypogonadal symptoms improved?If not, further adjustments may be needed.
Have any new symptoms developed?Certain side effects may be revealed through testing.
Are electrolytes, kidney function, and blood sugar unchanged?Testosterone therapy rarely impacts these, but it’s still prudent to monitor.

Based on results, your physician will collaborate with you to make appropriate treatment modifications to ensure therapy remains safe, effective, and aligned with your health goals.

You play a key role as well through monitoring any new symptoms in between testing. Keep your provider informed if you experience:

  • Breast enlargement, breast tenderness
  • Worsening sleep apnea
  • Fluid retention, swelling of feet/ankles
  • Headaches or migraines
  • Changes in mood, aggression or irritability
  • Yellowing skin/eyes, abdominal pain (liver concerns)

Testing enables early identification of potential adverse reactions or side effects. By being actively engaged and communicating openly with your provider, adjustments can be made to tailor therapy for your unique physiology and sensitivities.

The Road Back to Vitality

Like so many other medical treatments, testosterone replacement therapy does not come in a one-size-fits-all package. Finding the optimal regimen that restores your testosterone while minimizing risks of therapy takes diligence. The payoff? Many men treated report increased energy, libido, erectile function, muscle strength, motivation, and general zest for life.

Working as a team with your healthcare provider, monitoring your lab markers at the start of treatment and at regular intervals throughout TRT allows you to reclaim your health and masculinity. Tiny fine-tuning tweaks add up over months and years for long-term safety and success. You took the first step by having your testosterone checked. Now committed follow-through with blood testing will help you on the road back to becoming your best self again.

Regain Your Vitality with TRT – Start Your Lab Testing Today

If low testosterone may be behind your symptoms, don’t keep struggling in silence. At Physician’s Rejuvenation Centers, our experienced providers specialize in testosterone replacement done right through meticulous lab testing before and during treatment. Contact us to schedule a consultation today and get on the path to feeling like your old self again!