Which Blood Tests Matter Before Considering Testosterone Therapy?
Men often focus on a single number when assessing testosterone — usually total testosterone. While this is an important marker, it is only one part of a broader clinical picture. Relying on testosterone alone can lead to missed diagnoses, inappropriate treatment, or unnecessary concern.
A proper assessment before considering testosterone therapy should involve a structured set of blood tests that help explain why symptoms are present, not just whether testosterone appears low.
Why Comprehensive Blood Testing Is Essential
Symptoms commonly attributed to low testosterone — fatigue, low libido, poor recovery, mood changes — are non-specific. These symptoms can arise from sleep disorders, nutritional deficiencies, thyroid disease, alcohol use, stress, or metabolic conditions.
Without comprehensive blood testing, testosterone therapy risks becoming a default response rather than a considered medical decision.
Key Blood Tests That Provide Clinical Context
Total testosterone
Total testosterone reflects how much testosterone the body is producing at the time of testing. It is an important screening test, but it should always be interpreted in context.
Levels vary depending on sleep, illness, stress and time of day, which is why repeat morning testing is often required.
SHBG
SHBG influences how much testosterone is available to tissues. Abnormal SHBG levels can explain why symptoms do not align with total testosterone results.
Including SHBG allows testosterone results to be interpreted meaningfully rather than in isolation.
Full blood count
A full blood count provides information about red blood cell levels, oxygen-carrying capacity and baseline haematological status. This is important both before treatment and during ongoing monitoring, as testosterone can influence red blood cell production.
Liver function tests
The liver plays a key role in hormone metabolism and SHBG production. Liver enzymes can be affected by alcohol intake, medications and metabolic health, all of which influence hormone balance.
Thyroid function
Thyroid disorders are a common and frequently overlooked cause of fatigue, weight changes and low energy. Thyroid hormones also affect SHBG production, making thyroid testing essential when assessing hormonal symptoms.
Prolactin
Prolactin is an often-missed but important hormone in men. Elevated prolactin can suppress testosterone signalling and contribute to symptoms such as low libido, erectile dysfunction, fatigue and reduced motivation.
Raised prolactin may be related to medications, stress, pituitary conditions or other medical issues. Identifying this early can prevent unnecessary testosterone treatment and direct appropriate investigation.
Calcium
Calcium is not directly related to testosterone production, but abnormal calcium levels can indicate underlying endocrine or metabolic issues that contribute to fatigue, weakness or poor wellbeing.
Persistently elevated calcium may warrant further assessment for parathyroid disorders or other medical conditions that can affect energy levels and overall health.
Metabolic markers
Markers such as glucose and cholesterol provide insight into metabolic health. Metabolic dysfunction can contribute to low energy, reduced motivation and poor recovery independent of testosterone levels.
Why Testosterone Alone Is Not Enough
Assessing testosterone without considering other blood markers can lead to incomplete conclusions. Men may be started on treatment without addressing sleep apnoea, thyroid disease, prolactin abnormalities, nutritional deficiencies or metabolic issues.
Comprehensive blood testing allows clinicians to determine whether testosterone is the primary contributor to symptoms or part of a broader health picture.
When Blood Tests Support Considering TRT
Testosterone therapy may be appropriate when:
Testosterone levels are consistently low on repeat testing
Symptoms are significant and persistent
Other hormonal and medical causes have been assessed
Blood results support a primary hormonal issue
Even then, treatment decisions should be individualised and carefully monitored.
A Structured Assessment Leads to Better Outcomes
Men benefit most when blood tests are used to guide understanding rather than to justify treatment prematurely. Identifying reversible causes often leads to improvement without long-term therapy, while true deficiencies become clearer when all relevant markers are assessed.
Good hormone care starts with asking the right questions — and ordering the right tests.
Disclaimer
Information in this article is general in nature and does not constitute medical advice. TRT is a medical treatment that requires proper diagnosis, blood testing and doctor supervision. Always consult an Australian-registered medical practitioner before starting or changing any treatment.