What It Is

Total testosterone measures the entire amount of testosterone circulating in your blood, including both the protein-bound fraction (attached to SHBG and albumin) and the small free fraction. It is the primary marker used to diagnose hypogonadism (low T) and to monitor dosing adequacy on TRT. Produced mainly by the Leydig cells in the testes, testosterone drives muscle growth, bone density, red blood cell production, libido, mood, and cognitive function.

Why It's Tested on TRT

Total testosterone is the cornerstone lab for every TRT follow-up. It confirms your dosing protocol is bringing levels into the therapeutic range and helps your provider titrate the dose up or down. Drawing blood at trough (the day of or the day before your next injection) gives the most accurate picture of your lowest circulating level, ensuring you stay above the symptomatic threshold throughout your dosing cycle.

Reference Ranges (Males)

What Abnormal Results Mean on TRT

• Below range (<264 ng/dL): Dose is insufficient, absorption issues, or poor injection technique. Symptoms of low T (fatigue, low libido, brain fog) likely persist.
• Low-normal (264–500 ng/dL): Many men still experience symptoms in this range. A dose increase or protocol change (e.g., more frequent injections) is often warranted.
• Optimal (600–900 ng/dL): Sweet spot for most men — symptom resolution with minimal side-effect risk.
• Supraphysiologic (>1,000 ng/dL): Increased risk of polycythemia, acne, hair loss, mood changes. Dose reduction recommended.

Interventions

What It Is

Prostate-specific antigen (PSA) is a protein produced exclusively by prostate cells. A small amount normally leaks into the bloodstream, and the PSA blood test measures that concentration. Elevated PSA can indicate benign prostatic hyperplasia (BPH), prostatitis (prostate inflammation/infection), or prostate cancer, though it is not cancer-specific on its own.

Why It's Tested on TRT

Testosterone therapy can cause a modest increase in PSA, typically 0.3–0.5 ng/mL in the first 6–12 months, because testosterone stimulates prostate cell growth. Monitoring PSA ensures any clinically significant rise is caught early. A rapid increase (>1.4 ng/mL over 12 months) or crossing the 4.0 ng/mL threshold warrants further evaluation, including possible urology referral. Baseline PSA should be drawn before starting TRT, with follow-up at 3, 6, and 12 months, then annually.

Reference Ranges (Males)

What Abnormal Results Mean on TRT

• < 2.0 ng/mL: Ideal. Low risk. Continue routine monitoring.
• 2.0 – 4.0 ng/mL: Gray zone. Evaluate trend over time. Consider free PSA ratio or PSA density if rising.
• > 4.0 ng/mL: Warrants urology referral, digital rectal exam, and possible prostate MRI or biopsy. TRT may need to be paused pending evaluation.
• Velocity > 0.75 ng/mL/year: Suspicious regardless of absolute value. Urology referral recommended.

Interventions

What It Is

The comprehensive metabolic panel is a group of 14 blood tests that provide a snapshot of your body's chemical balance and metabolism. It evaluates kidney function (BUN, Creatinine, eGFR, BUN/Creatinine Ratio), liver function (ALP, ALT, AST, Total Bilirubin, Albumin, Total Protein), electrolyte balance (Sodium, Potassium, CO2, Chloride), calcium, and fasting blood glucose.

Why It's Tested on TRT

Testosterone is metabolized by the liver, so monitoring liver enzymes (ALT, AST, ALP) ensures hepatic safety. Kidney markers (BUN, creatinine, eGFR) are important because TRT can increase muscle mass, which raises creatinine independently of kidney damage. Glucose monitoring detects insulin resistance changes, as TRT often improves insulin sensitivity. Electrolytes and calcium are checked for overall metabolic stability.

Reference Ranges (Males)

What Abnormal Results Mean on TRT

• Elevated ALT/AST: May indicate liver stress. Injectable cypionate rarely causes significant liver enzyme elevation. Heavy training can also raise AST. If ALT > 3x upper limit, further hepatic workup is needed.
• Elevated creatinine / low eGFR: On TRT, increased muscle mass raises creatinine production, which can lower calculated eGFR without true kidney damage. Dehydration also raises creatinine.
• Elevated fasting glucose: TRT often improves insulin sensitivity over time. Values 100–125 mg/dL indicate prediabetes.
• Low albumin: May suggest chronic inflammation, liver dysfunction, or malnutrition — affects testosterone binding (albumin loosely binds ~50% of total T).

Interventions

What It Is

The complete blood count with differential evaluates all major blood cell populations: red blood cells (WBC, RBC, Hemoglobin, Hematocrit, MCV, MCH, MCHC, RDW), platelets, and the full white blood cell differential (Neutrophils, Lymphocytes, Monocytes, Eosinophils, Basophils). The differential breaks down which types of white cells are present, giving insight into immune function, inflammation, and infection status.

Why It's Tested on TRT

Testosterone powerfully stimulates erythropoiesis (red blood cell production) by increasing erythropoietin (EPO) from the kidneys. This is why TRT is the number one cause of secondary polycythemia in men. Elevated hematocrit increases blood viscosity, raising the risk of blood clots, stroke, and cardiovascular events. If hematocrit exceeds 54%, intervention is required. The WBC differential also detects infection, inflammation, or immune issues that can affect testosterone metabolism.

Reference Ranges (Males)

What Abnormal Results Mean on TRT

• Elevated hematocrit (> 51%): TRT-induced erythrocytosis. If hematocrit exceeds 54%, thromboembolic risk increases significantly. Therapeutic phlebotomy (blood donation) is first-line treatment.
• Elevated hemoglobin (> 17.7 g/dL): Parallels hematocrit elevation. Often the first marker to trigger intervention on TRT.
• Elevated RDW (> 15.4%): Suggests mixed red cell populations, which can occur when TRT rapidly stimulates new (larger) red blood cells alongside older cells.
• Elevated neutrophils / low lymphocytes: May suggest chronic stress, inflammation, or infection. The neutrophil-to-lymphocyte ratio (NLR) is an independent cardiovascular risk marker.
• Elevated eosinophils: May indicate allergic response, parasitic infection, or autoimmune activity.

Interventions

Full write-ups for these four tests are covered in the Entry Tier above. All remain part of the Baseline panel.

What It Is

Free testosterone is the small fraction of total testosterone (typically 2–3%) that circulates unbound to proteins in the blood. Unlike the majority of testosterone that is bound to sex hormone-binding globulin (SHBG) or albumin, free testosterone is immediately available to enter cells and activate androgen receptors. It is the biologically active form that directly drives muscle growth, libido, energy, mood, and cognitive function.

Why It's Tested on TRT

A man can have a normal total testosterone level but still experience symptoms of low T if his SHBG is elevated, which traps testosterone in its bound form. Free testosterone reveals the true amount of bioavailable hormone reaching your tissues. On TRT, monitoring free T ensures the therapy is delivering adequate active hormone, not just raising total numbers. It is particularly important for men over 40, as SHBG rises approximately 1–2% per year with age.

Reference Ranges (Males)

What Abnormal Results Mean on TRT

• Low free T (< 10 ng/dL) with normal total T: Elevated SHBG is binding most of the testosterone. Common with aging, hyperthyroidism, liver disease, or anticonvulsants. Symptoms of low T persist despite "normal" labs.
• Low free T with low total T: Dose increase warranted. Both forms are insufficient.
• Optimal free T (15–25 ng/dL): Best correlation with symptom resolution and quality of life improvements on TRT.
• Very high free T (> 30 ng/dL): Risk of increased estrogen conversion (aromatization), acne, hair loss, irritability, and polycythemia. Dose reduction may be needed.

Interventions

What It Is

Luteinizing hormone (LH) is a gonadotropin produced by the anterior pituitary gland. In men, LH signals the Leydig cells in the testes to produce testosterone. It is released in a pulsatile pattern, regulated by gonadotropin-releasing hormone (GnRH) from the hypothalamus. LH is a key player in the hypothalamic-pituitary-gonadal (HPG) axis — the hormonal feedback loop that controls testosterone production.

Why It's Tested on TRT

When you take exogenous testosterone, your brain detects the elevated level and suppresses GnRH release, which in turn suppresses LH to near-zero. This is expected and normal on TRT. A suppressed LH confirms your body is absorbing the exogenous testosterone. If LH is NOT suppressed on TRT, it may indicate non-compliance, poor absorption, or a pituitary adenoma. LH is also critical for pre-TRT diagnosis: elevated LH with low testosterone indicates primary hypogonadism (testicular failure), while low LH with low testosterone indicates secondary hypogonadism (pituitary/hypothalamic issue).

Reference Ranges (Males)

What Abnormal Results Mean on TRT

• Suppressed / undetectable (< 0.5 mIU/mL): Expected on exogenous testosterone. No action needed.
• Detectable / normal range while on TRT: Unexpected. Evaluate compliance, injection technique, and absorption.
• Pre-TRT elevated (> 8.6 mIU/mL): Indicates primary hypogonadism — the pituitary is working hard but the testes cannot produce adequate testosterone.
• Pre-TRT low (< 1.7 mIU/mL) with low T: Indicates secondary hypogonadism. Pituitary MRI should be considered.

Interventions

What It Is

Follicle-stimulating hormone (FSH) is the second gonadotropin produced by the anterior pituitary gland. In men, FSH acts on the Sertoli cells in the seminiferous tubules of the testes, driving spermatogenesis (sperm production). While LH controls testosterone production, FSH controls fertility — the two work in tandem within the HPG axis.

Why It's Tested on TRT

Like LH, FSH will be suppressed to near-zero on exogenous testosterone because the pituitary shuts down gonadotropin secretion when it detects adequate circulating testosterone. This suppression is why TRT causes reduced sperm production and potential infertility. Monitoring FSH is critical for men who want to preserve fertility while on TRT, as it quantifies how profoundly spermatogenesis is being suppressed.

Reference Ranges (Males)

What Abnormal Results Mean on TRT

• Suppressed / undetectable (< 0.7 mIU/mL): Expected on TRT. Spermatogenesis is likely impaired. If fertility is not a concern, this is normal and requires no intervention.
• Detectable while on TRT: Suggests compliance or absorption issues. Could also indicate concurrent HCG use is partially maintaining pituitary activity.
• Pre-TRT elevated (> 12.4 mIU/mL): Suggests primary testicular failure.
• Pre-TRT low with low T: Indicates secondary (central) hypogonadism. Consider pituitary workup.

Interventions

What It Is

Estradiol (E2) is the primary estrogen in men, produced mainly through the conversion (aromatization) of testosterone by the enzyme aromatase, primarily in adipose tissue, the liver, and the testes. Despite being classified as a "female hormone," estradiol plays essential roles in male health: bone density, cardiovascular function, libido, mood, cognitive function, and joint health all depend on maintaining adequate estradiol levels.

Why It's Tested on TRT

When testosterone levels rise on TRT, estradiol typically rises proportionally because more testosterone is available for aromatization. Both too much and too little estradiol cause problems. Elevated estradiol causes water retention, gynecomastia (breast tissue development), mood swings, and reduced libido. Low estradiol (often from over-use of aromatase inhibitors) causes joint pain, low libido, depression, brain fog, and accelerated bone loss. Monitoring estradiol allows your provider to keep it in the optimal range for your body composition and symptom profile.

Reference Ranges (Males)

What Abnormal Results Mean on TRT

• Optimal (20–40 pg/mL): Best range for most men on TRT. Libido, mood, bone density, and cardiovascular markers are supported at these levels.
• Elevated (> 40–50 pg/mL): Excess aromatization. Symptoms: water retention, mood swings, nipple sensitivity, reduced libido. Common in men with higher body fat or on higher testosterone doses.
• Very high (> 60 pg/mL): Significant estrogen excess. Aromatase inhibitor therapy or dose reduction indicated.
• Low (< 15 pg/mL): Often from AI over-use. Symptoms: joint aches, low libido, depression, brain fog, bone loss. Reduce or stop AI.

Interventions

Full write-ups for these tests are covered in the Entry Tier and Baseline Tier above. All remain part of the Optimized panel.

What It Is

Sex hormone-binding globulin (SHBG) is a glycoprotein produced by the liver that tightly binds testosterone and estradiol in the bloodstream. Approximately 44% of circulating testosterone is bound to SHBG (unavailable to cells), about 50% is loosely bound to albumin (partially available), and only 2–3% is free (immediately bioactive). SHBG acts as a hormonal reservoir and regulator — high SHBG reduces the amount of testosterone available to tissues, even when total testosterone levels appear normal.

Why It's Tested on TRT

SHBG is the critical missing piece when total testosterone looks good but symptoms of low T persist. Elevated SHBG binds more testosterone, dramatically reducing free and bioavailable T. SHBG rises with age, liver disease, hyperthyroidism, caloric restriction, and certain medications. Conversely, low SHBG (common with obesity, insulin resistance, and hypothyroidism) increases free testosterone but can also accelerate aromatization to estrogen. Measuring SHBG allows precise calculation of bioavailable testosterone and guides dosing strategy.

Reference Ranges (Males)

What Abnormal Results Mean on TRT

• High SHBG (> 57 nmol/L): Testosterone is being trapped. Free T will be low even if total T is in range. Common causes: aging, hyperthyroidism, liver cirrhosis, anticonvulsants, excessive alcohol. Patients feel low-T symptoms despite adequate TRT dose.
• Optimal SHBG (20–40 nmol/L): Good balance of total and free testosterone. TRT dosing is most efficient in this range.
• Low SHBG (< 10 nmol/L): More free testosterone is available, but rapid clearance can cause peaks and troughs. High free T may drive excess aromatization to estradiol, causing gynecomastia, water retention, and mood swings. Common with obesity and insulin resistance.

Interventions

What It Is

Thyroid-stimulating hormone is produced by the anterior pituitary gland and acts as the master regulator of thyroid function. TSH tells the thyroid gland to produce thyroid hormones (T4 and T3), which control metabolism, energy production, body temperature, heart rate, and protein synthesis. TSH operates on a negative feedback loop: when thyroid hormones are low, TSH rises; when thyroid hormones are adequate, TSH decreases.

Why It's Tested on TRT

Thyroid function and testosterone are deeply interconnected. Hypothyroidism increases SHBG, which binds more testosterone and reduces free T — potentially undermining TRT effectiveness. Symptoms of hypothyroidism (fatigue, weight gain, brain fog, depression) overlap significantly with low testosterone symptoms, making it essential to rule out or co-manage thyroid dysfunction. Optimizing thyroid function amplifies the benefits of TRT.

Reference Ranges (Males)

What Abnormal Results Mean on TRT

• Elevated TSH (> 4.5 mIU/L): Indicates hypothyroidism. Causes fatigue, weight gain, constipation, cold intolerance, and elevated SHBG — all of which blunt TRT benefits.
• TSH 2.5–4.5 mIU/L: Subclinical hypothyroidism. Many functional medicine providers treat in this range if symptoms are present.
• Low TSH (< 0.45 mIU/L): Suggests hyperthyroidism or excessive thyroid medication. Can cause anxiety, rapid heart rate, weight loss, and elevated SHBG.
• TSH 1.0–2.5 mIU/L: Optimal range. Best metabolic function and synergy with TRT.

Interventions

What It Is

The lipid panel measures the major fats and fat-like substances in your blood: total cholesterol, LDL ("bad" cholesterol), HDL ("good" cholesterol), triglycerides, and calculated VLDL. Cholesterol is essential for hormone production — all steroid hormones, including testosterone, are synthesized from cholesterol — but imbalanced lipids increase the risk of atherosclerosis, heart attack, and stroke.

Why It's Tested on TRT

Testosterone therapy has a complex relationship with lipid metabolism. TRT generally improves the overall lipid profile by reducing total cholesterol and triglycerides. However, supraphysiologic doses can lower HDL cholesterol. Lipid panels are recommended at baseline, 6 months, and annually on TRT to track cardiovascular risk trends.

Reference Ranges (Males)

What Abnormal Results Mean on TRT

• Elevated LDL (> 130 mg/dL): Increased cardiovascular risk. Not typically worsened by TRT at physiologic doses, but lifestyle, genetics, and diet are primary drivers.
• Low HDL (< 40 mg/dL): Supraphysiologic TRT doses or oral androgens can suppress HDL. This is one reason to keep testosterone within the therapeutic range.
• Elevated triglycerides (> 150 mg/dL): Strongly associated with insulin resistance, metabolic syndrome, and poor diet. TRT often helps lower triglycerides over time.
• Very low total cholesterol (< 150 mg/dL): Can impair steroid hormone synthesis. Adequate cholesterol is needed as a precursor for testosterone production.

Interventions

Full write-ups for these tests are covered in the Entry, Baseline, and Optimized tiers above. All remain part of the Ultimate panel.

What It Is

Prolactin is a hormone produced by the anterior pituitary gland. While primarily known for stimulating milk production in women, prolactin plays an important role in male reproductive health by regulating gonadotropin secretion and testicular function. In men, prolactin helps modulate LH receptor sensitivity in the testes and influences sexual function and mood.

Why It's Tested on TRT

Elevated prolactin (hyperprolactinemia) is a frequently overlooked cause of low testosterone that fails to respond adequately to TRT. High prolactin suppresses GnRH release from the hypothalamus, which in turn suppresses LH and FSH, reducing testosterone production. Symptoms of hyperprolactinemia in men include low libido, erectile dysfunction, gynecomastia, and fatigue — all of which mimic low testosterone. A pituitary adenoma (prolactinoma) is the most common cause of significantly elevated prolactin and requires MRI evaluation.

Reference Ranges (Males)

What Abnormal Results Mean on TRT

• Optimal (< 15 ng/mL): Normal. No prolactin-related suppression of testosterone or gonadotropins.
• Mildly elevated (18–40 ng/mL): Can be caused by stress, vigorous exercise before the draw, certain medications (antipsychotics, antidepressants, metoclopramide), hypothyroidism, or chronic kidney disease. Repeat testing and medication review warranted.
• Moderately elevated (40–100 ng/mL): High suspicion for pituitary adenoma (prolactinoma) or significant medication effect. MRI of the pituitary is recommended.
• Severely elevated (> 100 ng/mL): Strongly suggests a macroprolactinoma. Dopamine agonist therapy (cabergoline) is first-line treatment.

Interventions

What It Is

Insulin-like growth factor 1 (IGF-1) is a peptide hormone produced primarily by the liver in response to growth hormone (GH) stimulation. It mediates many of the anabolic effects attributed to growth hormone, including muscle growth, bone density, tissue repair, collagen synthesis, and cellular regeneration. IGF-1 levels serve as a stable, reliable proxy for growth hormone status because GH itself is released in pulsatile bursts and is difficult to measure accurately with a single blood draw.

Why It's Tested on TRT

Testosterone and growth hormone have a synergistic relationship. TRT can modestly increase IGF-1 levels by stimulating GH release and enhancing hepatic IGF-1 production. Monitoring IGF-1 provides insight into the overall anabolic environment of the body — when both testosterone and IGF-1 are optimized, patients experience the greatest improvements in muscle mass, recovery, body composition, and anti-aging markers. Low IGF-1 despite adequate TRT may indicate GH deficiency, poor sleep, caloric restriction, or liver dysfunction.

Reference Ranges (Males)

What Abnormal Results Mean on TRT

• Low IGF-1 (below age-adjusted range): May indicate growth hormone deficiency, inadequate sleep, caloric restriction, liver disease, or chronic illness. Symptoms include difficulty building muscle, poor recovery, thin skin, increased abdominal fat, and accelerated aging.
• Low-normal IGF-1: Suboptimal anabolic environment. Optimizing sleep, nutrition, and exercise can often raise levels.
• Optimal IGF-1 (upper third of age-adjusted range): Associated with best body composition, recovery, cognitive function, and longevity markers.
• Very high IGF-1 (> 300 ng/mL): If not on GH therapy, warrants evaluation for pituitary adenoma (acromegaly).

Interventions

What It Is

Hemoglobin A1c (HbA1c or A1C) measures the percentage of hemoglobin molecules in your red blood cells that have glucose attached to them. Because red blood cells live approximately 90 days, A1C reflects your average blood glucose level over the past 2–3 months — making it far more informative than a single fasting glucose reading. It is the gold standard test for diagnosing and monitoring diabetes and prediabetes.

Why It's Tested on TRT

Testosterone and metabolic health are closely linked. Men with low testosterone have higher rates of insulin resistance, metabolic syndrome, and type 2 diabetes. TRT has been shown to improve insulin sensitivity and lower A1C in hypogonadal men with metabolic dysfunction — making it a meaningful marker for tracking the metabolic benefits of testosterone therapy over time. Uncontrolled blood sugar also accelerates SHBG changes, impairs testosterone production, and increases cardiovascular risk, all of which are relevant to TRT outcomes.

Reference Ranges

What Abnormal Results Mean on TRT

• A1C < 5.4%: Optimal. Excellent metabolic control and low diabetes risk. TRT is well-positioned to support body composition and energy goals.
• A1C 5.4–5.7%: Normal but trending. Lifestyle optimization recommended to prevent progression.
• A1C 5.7–6.4% (prediabetes): Significant metabolic dysfunction. TRT may help, but dietary and lifestyle intervention is essential. Consider GLP-1 therapy.
• A1C ≥ 6.5% (diabetes): Active diabetes management required before TRT goals can be fully optimized. Elevated glucose impairs testosterone signaling and accelerates cardiovascular risk.

Interventions

What It Is

Cortisol AM measures blood cortisol at its natural daily peak — between 7 and 9 AM. Cortisol is the body's primary stress hormone, produced by the adrenal cortex under the direction of ACTH (adrenocorticotropic hormone) from the pituitary gland. It follows a circadian rhythm: highest in the morning to mobilize energy for the day, lowest at night to allow recovery. Cortisol regulates blood sugar, immune function, blood pressure, inflammation, and the stress response.

Why It's Tested on TRT

Cortisol and testosterone are inversely related — chronically elevated cortisol directly suppresses the HPG axis, reducing GnRH, LH, and ultimately testosterone production. Men under chronic stress often see blunted TRT results because cortisol counteracts testosterone's anabolic signaling at the receptor level. Conversely, very low cortisol may indicate adrenal insufficiency (Addison's disease) or HPA axis dysfunction, which can cause profound fatigue that mimics or compounds low testosterone. Measuring Cortisol AM standardizes the timing so results are clinically meaningful.

Reference Ranges

What Abnormal Results Mean on TRT

• Optimal AM cortisol (12–20 mcg/dL): Healthy HPA axis. Morning cortisol peak is intact and adrenal function is adequate.
• Low AM cortisol (< 6 mcg/dL): May indicate adrenal insufficiency or HPA axis suppression (from chronic steroid use, long-term stress, or illness). Symptoms: profound fatigue, salt cravings, dizziness, hypoglycemia. Endocrinology referral for stimulation testing (ACTH stim test) is recommended.
• Chronically high AM cortisol (> 20 mcg/dL): Suggests chronic physiological stress, Cushing’s syndrome, or HPA hyperactivation. Elevated cortisol suppresses testosterone, impairs sleep, promotes abdominal fat storage, and increases insulin resistance.
• Blunted diurnal rhythm (high AM + high PM): Associated with burnout, PTSD, metabolic syndrome, and sleep disorders. Consider 4-point salivary cortisol testing for a complete daily curve.

Interventions

What It Is

C-reactive protein (CRP) is an acute-phase protein produced by the liver in response to inflammation anywhere in the body. High-sensitivity CRP (hs-CRP) is a more precise version of the standard CRP test, capable of detecting low-grade systemic inflammation that falls below the threshold of standard CRP assays. While standard CRP is used to identify active infections or acute inflammatory conditions, hs-CRP is used for cardiovascular risk stratification and to detect the subclinical, chronic, low-grade inflammation that underlies metabolic syndrome, atherosclerosis, insulin resistance, and hormonal dysfunction.

Why It's Tested on TRT

Chronic low-grade inflammation directly suppresses testosterone production by impairing Leydig cell function and disrupting the HPG axis at the hypothalamic level. Elevated hs-CRP is also an independent cardiovascular risk factor, which matters on TRT because testosterone therapy modestly raises hematocrit and can affect lipid profiles. Monitoring hs-CRP helps identify patients whose TRT results are being blunted by a high inflammatory burden — and flags cardiovascular risk that needs to be addressed alongside hormone optimization. Successful TRT combined with improved body composition and lifestyle often lowers hs-CRP over time.

Reference Ranges

What Abnormal Results Mean on TRT

• hs-CRP < 0.5 mg/L (optimal): Minimal systemic inflammation. Hormonal optimization, cardiovascular protection, and body composition goals are all well-positioned.
• hs-CRP 1–3 mg/L (average risk): Subclinical inflammation present. Diet, sleep, exercise, and visceral fat reduction are the primary levers. TRT outcomes may be partially blunted.
• hs-CRP > 3 mg/L (high risk): Significant inflammatory load. Evaluate for metabolic syndrome, sleep apnea, dietary contributors, or occult infection/autoimmune process. Prioritize anti-inflammatory intervention.
• hs-CRP > 10 mg/L: Suggests acute infection, acute injury, or flare of an inflammatory disease. Repeat after resolution before using for cardiovascular risk assessment.

Interventions

What It Is

Iron Studies is a panel of three related tests that together give a complete picture of iron metabolism: Serum Iron measures the amount of iron currently circulating in the blood bound to transferrin. TIBC (Total Iron Binding Capacity) reflects the maximum amount of iron that transferrin in the blood could carry — a functional measure of transferrin availability. Ferritin is an intracellular protein that stores iron; the serum ferritin level is the most sensitive and specific marker for total body iron stores and is the first value to drop in iron depletion, even before anemia develops.

Why It's Tested on TRT

TRT stimulates erythropoiesis (red blood cell production) through increased EPO signaling, which significantly increases iron demand. Men on TRT who require therapeutic phlebotomy to manage polycythemia (elevated hematocrit) are especially at risk for iron depletion — repeated blood donation depletes stored iron faster than diet can replenish it. Depleted ferritin causes fatigue, poor recovery, brain fog, and impaired athletic performance that can be easily mistaken for undertreated hypogonadism. Conversely, iron overload (hemochromatosis, excess supplementation) causes liver damage, joint disease, and heart failure. Iron Studies allows accurate targeting of phlebotomy frequency and iron supplementation decisions without guessing.

Reference Ranges (Males)

What Abnormal Results Mean on TRT

• Low ferritin (< 30 ng/mL): Iron-depleted stores. Even without anemia, low ferritin causes fatigue, exercise intolerance, hair thinning, and reduced VO2 max. Common after repeated therapeutic phlebotomy. Iron supplementation and reduced phlebotomy frequency are indicated.
• Low serum iron + high TIBC: Classic iron deficiency pattern. The body upregulates transferrin production (raises TIBC) in an attempt to scavenge more iron from circulation. Indicates depletion outpacing intake.
• Optimal ferritin (50–150 ng/mL): Iron stores are adequate to support erythropoiesis without approaching overload territory.
• High ferritin (> 300 ng/mL): May reflect iron overload, chronic inflammation, liver disease, or metabolic syndrome. Elevated ferritin from hemochromatosis causes organ damage over time. Evaluate with transferrin saturation; if > 45%, hereditary hemochromatosis testing (HFE gene) is warranted.
• High serum iron + low TIBC + high ferritin: Pattern consistent with iron overload. Therapeutic phlebotomy is the treatment, but the root cause must be distinguished in the TRT context.

Interventions

What It Is

A Kidney Profile goes beyond the renal markers already included in the CMP (BUN, Creatinine, eGFR) to provide a more complete picture of glomerular and tubular function. Key add-on markers include: Cystatin C, a protein filtered freely by the glomerulus and unaffected by muscle mass — making it a superior GFR estimator in muscular men where creatinine-based eGFR systematically overestimates kidney function. Urine Microalbumin (or Urine Albumin-to-Creatinine Ratio, ACR) detects early tubular and glomerular damage before serum creatinine rises. BUN/Creatinine Ratio helps distinguish pre-renal (dehydration, poor perfusion) from intrinsic renal causes of elevated creatinine.

Why It's Tested on TRT

TRT increases muscle mass, which in turn raises serum creatinine and can make standard eGFR look falsely low in well-muscled men. Cystatin C provides a muscle-mass-independent GFR estimate, preventing unnecessary concern or protocol changes based on an artifactually elevated creatinine. Beyond muscle artifact, some anabolic and accessory compounds used alongside TRT (NSAIDs, oral compounds, certain peptides) are nephrotoxic. Hypertension — a known side effect of erythrocytosis from TRT — is a leading cause of chronic kidney disease, making early microalbumin detection valuable for men on long-term TRT with elevated hematocrit or blood pressure.

Reference Ranges

What Abnormal Results Mean on TRT

• Elevated creatinine with normal Cystatin C: Likely muscle mass artifact in a well-muscled man on TRT. True GFR is likely normal. No clinical action needed; use Cystatin C-based eGFR going forward.
• Elevated creatinine AND elevated Cystatin C: True reduction in GFR. Evaluate for hypertension, dehydration, nephrotoxic medications, or intrinsic renal disease. Nephrology referral if eGFR < 60.
• Microalbumin ACR 30–300 mg/g (microalbuminuria): Early-stage glomerular damage. Tighten blood pressure control (<130/80), optimize glycemic control, reduce NSAID use.
• BUN/Creatinine ratio > 20: Suggests pre-renal azotemia (dehydration, reduced renal perfusion). Increase fluid intake; assess blood pressure and cardiac output.

Interventions

What It Is

A comprehensive Hepatic Function Panel expands on the liver markers included in the CMP (AST, ALT, ALP, Bilirubin, Albumin) by adding GGT (Gamma-Glutamyl Transferase) — a highly sensitive marker for hepatocellular injury, alcohol use, and oxidative stress that is not included in standard CMPs. Together, these six markers identify hepatocellular injury (AST/ALT), cholestatic disease (ALP/GGT/Bilirubin), and synthetic function (Albumin). The pattern of elevation across these markers allows differentiation between hepatocellular damage, cholestasis, alcohol use, and fatty liver disease.

Why It's Tested on TRT

The liver is the primary site of sex hormone metabolism and SHBG production, making hepatic health central to TRT outcomes. Oral or sublingual testosterone formulations, 17α-alkylated compounds (Oxandrolone, Stanozolol), and certain peptides undergo significant first-pass hepatic metabolism and can elevate liver enzymes. Even injectable testosterone at high doses can modestly affect liver markers over time. GGT is particularly useful in TRT patients because it rises early with any hepatic oxidative stress and is a sensitive marker for fatty liver disease — which is common in the metabolic syndrome population that often seeks TRT. Albumin reflects the liver's synthetic capacity and is also a marker of nutritional adequacy; low albumin on TRT may indicate protein insufficiency that limits muscle-building response.

Reference Ranges

What Abnormal Results Mean on TRT

• Isolated AST elevation (normal ALT): Consider muscle source — heavy resistance training raises AST from skeletal muscle breakdown. Draw at least 48 hours after last intense workout.
• AST + ALT elevated (> 2× ULN): Hepatocellular injury pattern. Evaluate for NAFLD, alcohol, hepatotoxic medications, or viral hepatitis. If on an oral/17-aa compound, discontinue immediately.
• Elevated GGT with normal AST/ALT: Early NAFLD, alcohol use, or oxidative stress. Highly actionable with dietary and lifestyle changes before frank hepatitis develops.
• ALP elevated + GGT elevated: Cholestatic pattern. Evaluate for bile duct obstruction, primary biliary cholangitis, or drug-induced cholestasis.
• Low albumin (< 3.8 g/dL): Impaired hepatic synthetic function or protein malnutrition. TRT anabolic response will be blunted; protein intake and liver health must be addressed.

Interventions