What Bloodwork Do I Need Before Starting Testosterone? A Physician’s Guide

Before prescribing testosterone, a responsible physician needs to understand where you are starting. Symptoms alone are not sufficient. Laboratory assessment establishes the biochemical foundation upon which a safe, effective protocol is built.

The following is a guide to the bloodwork a thorough BHRT practice orders before initiating testosterone therapy, and why each marker matters.

The Core Hormonal Panel

Total Testosterone

The primary marker. Total testosterone measures the full amount of testosterone circulating in the blood, both bound and unbound. Reference ranges at most Ontario labs span roughly 8.4 to 28.8 nmol/L, but a level of 10 nmol/L in a 40 year old man, while technically within range, is not optimal.

Context matters more than the reference range. A physician experienced in testosterone optimization interprets your level in relation to your age, symptoms, and clinical picture.

Free Testosterone

Only 2 to 3 percent of total testosterone circulates in its unbound, biologically active form. Free testosterone is the fraction that actually enters cells and exerts its effects on muscle, brain, bone, and metabolic function.

A patient can have a total testosterone level that appears adequate while free testosterone is low, often due to elevated sex hormone binding globulin. Without measuring free testosterone, this common clinical scenario is missed entirely.

Sex Hormone Binding Globulin (SHBG)

SHBG is a protein produced by the liver that binds testosterone, rendering it inactive. Elevated SHBG effectively reduces the testosterone available to tissues, even when total testosterone appears normal.

SHBG rises with age, hyperthyroidism, liver disease, and certain medications. It decreases with obesity, insulin resistance, and hypothyroidism. Understanding SHBG is essential for interpreting total testosterone accurately and for selecting the appropriate delivery method and dosing strategy.

Estradiol (E2)

Testosterone is converted to estradiol via the aromatase enzyme, primarily in adipose tissue. Estradiol is not merely a female hormone. In men, it plays important roles in bone density, cardiovascular health, libido, and cognitive function.

However, estradiol that is disproportionately elevated relative to testosterone can contribute to water retention, mood disturbance, gynecomastia, and blunted response to testosterone therapy. Baseline estradiol establishes the starting ratio and informs whether aromatase activity is likely to be a factor during treatment.

Luteinizing Hormone (LH) and Follicle Stimulating Hormone (FSH)

LH and FSH are pituitary hormones that signal the testes to produce testosterone and sperm. Measuring them helps distinguish between primary hypogonadism (testicular insufficiency, where LH and FSH are elevated as the pituitary compensates) and secondary hypogonadism (pituitary or hypothalamic dysfunction, where LH and FSH are low or inappropriately normal despite low testosterone).

This distinction has implications for treatment approach and for understanding the underlying cause of hormonal decline.

Prolactin

Elevated prolactin can suppress testosterone production and is associated with reduced libido, erectile dysfunction, and fatigue. While uncommon, a pituitary prolactinoma must be ruled out in any man presenting with significantly low testosterone and elevated prolactin. A baseline level protects against missing this diagnosis.

DHEA-S

Dehydroepiandrosterone sulfate is an adrenal androgen precursor. It provides a window into adrenal function and overall androgen reserve. DHEA-S declines with age and chronic stress. In some patients, supporting DHEA alongside testosterone produces a more complete clinical response.

Metabolic and Cardiometabolic Markers

Testosterone does not operate in isolation. Metabolic health profoundly influences hormonal function, and testosterone therapy influences metabolic parameters. A comprehensive baseline captures both directions.

Fasting Glucose and Insulin

Insulin resistance is one of the most common and underdiagnosed contributors to hormonal dysfunction in men. Elevated fasting insulin, even with normal fasting glucose, signals metabolic stress that directly impairs testosterone production and increases aromatase activity in visceral fat. Elevated insulin also acts on the hypothalamus to suppress GnRH (gonadotropin releasing hormone) pulse frequency, reducing the pituitary’s stimulus to testosterone production at its source.

Measuring both glucose and insulin, not glucose alone, reveals the metabolic context in which testosterone therapy will operate. A fasting insulin above 8 to 10 µIU/mL with normal fasting glucose is the classic early signal of metabolic dysfunction. Without this information, you may initiate testosterone therapy into a hostile metabolic environment and see incomplete clinical response.

HbA1c

Glycated hemoglobin reflects average blood glucose over the preceding two to three months. It provides a more stable picture of glucose regulation than a single fasting glucose measurement. However, HbA1c alone can mask significant dysglycemia, particularly in the postprandial period. A normal HbA1c does not rule out underlying metabolic dysfunction, especially early insulin resistance when fasting glucose and fasting insulin reveal patterns that HbA1c alone would miss.

Testosterone therapy has been shown to improve insulin sensitivity in hypogonadal men, and tracking HbA1c over time captures this benefit. But measuring HbA1c in isolation without understanding baseline glucose dynamics and insulin response patterns means missing the opportunity for early metabolic intervention before initiating hormonal therapy.

Lipid Panel

A complete lipid panel, including total cholesterol, LDL, HDL, and triglycerides, establishes cardiovascular baseline. Testosterone therapy can influence lipid profiles, and a pre treatment baseline is essential for monitoring.

HDL, in particular, warrants attention. Supraphysiological testosterone doses can lower HDL, while physiological replacement typically has a neutral or mildly beneficial effect. Knowing the starting point allows the physician to detect any unfavorable trend early.

High Sensitivity C-Reactive Protein (hs-CRP)

A marker of systemic inflammation. Chronic low grade inflammation is associated with metabolic syndrome, cardiovascular risk, and impaired recovery. Baseline hs-CRP provides context for overall metabolic health and helps track the anti-inflammatory effects that optimized testosterone can produce.

Hematological Markers

Complete Blood Count (CBC) with Hematocrit

This is a non-negotiable baseline. Testosterone stimulates erythropoiesis, the production of red blood cells. An increase in hemoglobin and hematocrit is an expected and dose dependent effect of testosterone therapy.

Starting testosterone in a patient whose hematocrit is already elevated increases the risk of polycythemia, a condition where blood becomes excessively thick, raising the risk of clotting events. Baseline hematocrit defines the safety margin and informs the monitoring schedule.

Patients with a hematocrit above 52 percent at baseline require careful evaluation before initiating testosterone. Ongoing monitoring, typically every three to six months during the first year, is standard practice.

Ferritin

Iron status influences energy, cognitive function, and erythropoiesis. Low ferritin can independently cause fatigue that mimics or compounds the effects of low testosterone. Identifying iron deficiency before starting treatment prevents misattribution of persistent fatigue to an inadequate testosterone dose.

Liver and Kidney Function

Hepatic Panel (AST, ALT, GGT, Albumin)

The liver metabolizes testosterone and its metabolites. Elevated liver enzymes may indicate underlying hepatic stress that affects hormone metabolism. Baseline liver function also establishes a reference point for monitoring, particularly for patients using oral or sublingual testosterone preparations that undergo first pass hepatic processing.

SHBG is produced by the liver, so hepatic function directly influences the bioavailability of testosterone. Impaired liver function can alter SHBG levels in either direction, complicating dose titration without a clear baseline.

Creatinine and eGFR

Kidney function affects fluid balance, blood pressure, and the clearance of metabolites. A baseline renal panel ensures there are no contraindications and provides a reference for ongoing monitoring.

Thyroid Function

TSH, Free T3, Free T4

Thyroid function and testosterone production are deeply interconnected. Hypothyroidism can elevate SHBG, reduce free testosterone, and produce symptoms, fatigue, weight gain, cognitive fog, that overlap significantly with low testosterone.

Starting testosterone without assessing thyroid function risks treating the wrong condition, or only part of the picture. A complete thyroid panel ensures the clinical approach addresses all contributing factors.

Prostate Health

Prostate Specific Antigen (PSA)

PSA is a baseline screening marker for prostate health in men over 40, or younger men with risk factors. Testosterone does not cause prostate cancer, a position supported by extensive peer reviewed literature, but it is prudent to establish a baseline PSA before initiating therapy.

Ongoing PSA monitoring during testosterone therapy is standard practice. A stable or slowly rising PSA in the context of testosterone optimization is expected. A rapid or disproportionate rise warrants further evaluation.

A digital rectal examination, while outside the scope of bloodwork, is also recommended as part of the pre treatment assessment.

Additional Markers Worth Considering

Depending on the patient’s clinical presentation, a thorough physician may also include the following.

Vitamin D (25-OH)

Vitamin D functions as a hormone and plays a role in testosterone production, immune regulation, and bone health. Deficiency is common in Ontario, particularly through the winter months. Correcting vitamin D deficiency can independently improve testosterone levels and overall well being.

Cortisol (Morning)

Chronic stress depletes cortisol regulation and disrupts the hypothalamic pituitary gonadal axis. A morning cortisol level provides insight into adrenal function and stress physiology. In patients with significant fatigue or a history of prolonged stress, this marker adds valuable context.

Magnesium (RBC)

Red blood cell magnesium is a more accurate measure of tissue magnesium status than serum magnesium. Magnesium is a cofactor in hundreds of enzymatic reactions, including those involved in testosterone synthesis and sleep quality. Deficiency is widespread and easily corrected.

Why Comprehensive Bloodwork Matters

A single testosterone level tells you very little. It does not tell you whether the testosterone is bioavailable. It does not reveal whether insulin resistance is suppressing production. It does not indicate whether the liver is metabolizing hormones efficiently, whether the thyroid is contributing to symptoms, or whether hematocrit is already elevated.

Comprehensive bloodwork transforms a one dimensional number into a three dimensional clinical picture. It allows the physician to design a protocol that is precise, safe, and tailored to the individual. It establishes baselines against which every subsequent lab draw is compared. And it ensures that the decision to start testosterone, and every adjustment thereafter, is grounded in data.

Getting Your Bloodwork in Ontario

Patients across Ontario can complete bloodwork at any LifeLabs or Dynacare location. Many of the markers listed above can be requisitioned through OHIP when there is a documented clinical indication. Additional markers may be ordered through a private requisition, with costs typically ranging from $100 to $400 depending on the scope of the panel.

For patients working with a virtual BHRT physician, the process is straightforward: your requisition is sent electronically, you attend the nearest lab at your convenience, and results are reviewed in detail during your consultation.

The First Step

If you are experiencing symptoms of low testosterone, fatigue, reduced motivation, poor sleep, declining body composition, diminished libido, the first step is not a prescription. It is a thorough laboratory assessment. The bloodwork tells the story. A skilled physician reads it carefully and builds a protocol that respects the complexity of your physiology.

Continue Reading

If you found this useful, these related articles may deepen your understanding:

• How to Read Your Blood Work
• Testosterone Delivery Methods
• Testosterone and Cardiovascular Health: What the Research Actually Shows

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Dr. Handsun Xiao is a McGill trained physician (MD, CCFP) practicing functional medicine and bioidentical hormone therapy in Toronto, with virtual consultations available to patients across Ontario. He holds advanced BHRT certification through WorldLink Medical and IFM AFMCP training. Manus Solis offers physician led BHRT consultations with custom compounding through a dedicated Ontario pharmacy partner. To learn more or book a virtual consultation, visit manussolis.ca.