Men's Hormone Panel: What to Test Before Starting TRT or Peptide Therapy

Baseline labs before testosterone or peptide therapy do three jobs. They confirm the diagnosis, they establish a comparison point for monitoring, and — most importantly — they surface findings that change or contraindicate the plan. That third job is the one skipped by direct-to-consumer programs that test total testosterone and little else.

This is an educational overview of what a thorough panel includes. Which tests are appropriate for a given patient is a clinical decision.

The Hormonal Core

Total Testosterone

Drawn in the morning, generally before 10 a.m., and confirmed on a second occasion. This is the anchor, but on its own it is not interpretable.

SHBG and Free Testosterone

Sex hormone-binding globulin determines how much of the total is biologically available. SHBG rises with age and with hyperthyroidism; it falls with obesity, insulin resistance, and hypothyroidism.

The practical consequence: an obese man with low SHBG may have a low-normal total testosterone but adequate free testosterone, while an older lean man with high SHBG may have a normal total and genuinely low free levels. Ordering total testosterone without SHBG produces a number you cannot act on confidently.

LH and FSH

These separate the two forms of hypogonadism, and the distinction drives everything downstream:

• Primary (testicular failure) — low testosterone with elevated LH and FSH. The pituitary is signaling correctly; the testes are not responding.
• Secondary (pituitary/hypothalamic) — low testosterone with low or inappropriately normal LH and FSH. The signal itself is inadequate.

Secondary hypogonadism opens the door to treatments that restore the signal rather than replace the hormone — which is the relevant path for men concerned about fertility.

Estradiol

Testosterone aromatizes to estradiol, and men need estradiol for bone density, libido, and cardiovascular health. Both extremes cause problems. A sensitive (LC-MS/MS) assay is preferred in men, since standard immunoassays are poorly calibrated at male concentrations.

Prolactin

Elevated prolactin suppresses the HPG axis and can indicate a pituitary adenoma. A significantly elevated prolactin changes the workup immediately and warrants imaging — it is a low-cost test with a high-consequence finding.

Safety Markers That Change the Plan

Hematocrit and CBC

Testosterone stimulates erythropoiesis. Rising hematocrit is the most common dose-limiting effect of therapy, and a high baseline is a reason for caution before starting. This is monitored throughout treatment, not just at baseline.

PSA

Baseline PSA is standard before testosterone therapy in men over 40. Therapy is not currently believed to cause prostate cancer, but it can accelerate an existing occult cancer, so establishing a baseline and monitoring is the accepted approach.

Lipids and Metabolic Panel

Fasting glucose, HbA1c, fasting insulin, and a lipid panel. Insulin resistance and low testosterone travel together and reinforce one another; identifying the metabolic picture often reveals a driver worth treating directly.

Comprehensive Metabolic Panel

Liver and kidney function, relevant both as a baseline and because some delivery routes and adjunct medications warrant hepatic monitoring.

Screening the Confounders

Thyroid

TSH with free T4, and free T3 where indicated. Thyroid dysfunction mimics hypogonadism symptom for symptom and alters SHBG, which distorts testosterone interpretation.

Ferritin and Iron Studies

Iron deficiency causes fatigue and reduced exercise tolerance at a normal hemoglobin, and it is not rare in men — where, unlike in menstruating women, it warrants investigation of the cause rather than simple replacement.

Vitamin D

Commonly low, plausibly relevant to testosterone and musculoskeletal health, and cheap to correct.

Sleep Study

Not a blood test, but arguably the highest-yield item in this article for a fatigued man with low testosterone. Obstructive sleep apnea is common, frequently undiagnosed, lowers testosterone directly, and can be worsened by testosterone therapy. Our overview of low testosterone symptoms covers why this confounder matters so much.

Semen Analysis

For any man who may want children, this belongs in the baseline. Once exogenous testosterone has suppressed spermatogenesis, you no longer have a pre-treatment comparison.

Quick Reference

Before Peptide Therapy Specifically

For growth hormone secretagogues, providers commonly add IGF-1 as the practical readout of GH axis activity, along with fasting glucose and HbA1c, since GH axis stimulation can affect insulin sensitivity. Our peptide therapy overview covers the wider category.

Related reading: Newtropin's men's hormone optimization program

Frequently Asked Questions

What labs do I need before starting TRT?

At minimum: morning total testosterone confirmed twice, SHBG or free testosterone, LH, FSH, sensitive estradiol, prolactin, CBC with hematocrit, PSA if over 40, a comprehensive metabolic panel, lipids, HbA1c, and thyroid studies. A semen analysis is added for men who may want children.

Why does SHBG matter?

SHBG determines how much testosterone is biologically available. It shifts with age, obesity, thyroid status, and insulin resistance, so the same total testosterone can mean very different things in two men. Without it, the total is hard to act on.

What is the difference between primary and secondary hypogonadism?

Primary is testicular failure — low testosterone with elevated LH and FSH. Secondary is inadequate pituitary or hypothalamic signaling — low testosterone with low or normal LH and FSH. Secondary hypogonadism can sometimes be treated by restoring the signal, which preserves fertility.

How often should labs be repeated on therapy?

Protocols vary, but a common pattern is recheck at six to twelve weeks after starting or after a dose change, then periodically once stable. Hematocrit, PSA, and estradiol are the markers most commonly tracked long-term.

Do I need a sleep study?

If you have fatigue with low testosterone, snoring, witnessed apneas, or daytime sleepiness, it is one of the higher-yield tests available. Sleep apnea both lowers testosterone and can be worsened by testosterone therapy.

Can I use a direct-to-consumer testing kit?

They can be a starting point, but most test a narrow panel and few include SHBG, LH, FSH, sensitive estradiol, and prolactin. A result from one is a reason to see a provider, not a basis for starting therapy.