How to Start Growth Hormone Peptide Therapy: What Labs to Order First

Before you take your first dose of any growth hormone peptide, you need a specific set of baseline labs. That is not optional. Growth hormone peptide therapy labs determine whether you are a candidate, establish the benchmarks your clinician will track, and reveal any contraindications that could make treatment risky. The core panel includes IGF-1, fasting glucose, fasting insulin, HbA1c, a comprehensive metabolic panel, a full lipid panel, thyroid function, and a complete blood count. This guide walks through every test, explains why it matters, and tells you exactly what your results should look like before therapy begins.

Why Growth Hormone Peptide Therapy Labs Matter Before You Start

Skipping baseline labs is one of the most common mistakes in peptide therapy — and one of the most consequential.

Growth hormone (GH) secretagogues — peptides like CJC-1295, ipamorelin, and tesamorelin — work by stimulating the pituitary gland to release endogenous GH. That GH pulse triggers the liver to produce insulin-like growth factor-1 (IGF-1), which drives most of GH's downstream effects: fat metabolism, lean mass accretion, tissue repair, and sleep quality.1

The problem is this: if your IGF-1 is already at the top of its reference range, adding a GH secretagogue will push it further. Chronically elevated IGF-1 carries real risk — including worsened insulin resistance, fluid retention, and, in some literature, association with cancer promotion in individuals with pre-existing lesions.2

The same applies in reverse. If your fasting insulin is elevated and your HOMA-IR signals pre-diabetic physiology, certain GH peptides may worsen glucose tolerance in the short term before metabolic improvements emerge.3 Your clinician needs to know this before prescribing.

Baseline labs serve three functions:

• Confirm candidacy. Labs identify low GH axis activity that justifies therapy.
• Set benchmarks. They give you and your clinician a "before" to measure against.
• Catch contraindications. They surface liver dysfunction, thyroid pathology, or active malignancy markers that change the clinical picture entirely.

If you have been experiencing symptoms of low growth hormone — persistent fatigue, visceral fat accumulation, poor recovery, or disrupted sleep — these labs will tell you whether the GH axis is the driver.

The Essential Baseline Labs for Growth Hormone Peptide Therapy

Order these tests as a complete panel. Do not cherry-pick. Each biomarker serves a distinct diagnostic function, and your clinician will interpret them in context with each other.

Step 1: IGF-1 (Insulin-Like Growth Factor-1)

This is the single most important test before starting any GH peptide protocol.

IGF-1 is the primary downstream marker of GH secretion. A low-normal or below-range result in an adult with symptoms of GH insufficiency is the clearest clinical signal that GH-stimulating therapy may be appropriate.4

• Why it matters: IGF-1 reflects cumulative GH output over hours and days, making it far more clinically useful than a single GH reading (which fluctuates by the minute).
• What to look for: Reference ranges are age- and sex-adjusted. Adults aged 30–40 typically fall between 88–246 ng/mL; this narrows with age. A result below mid-range in a symptomatic adult supports GH secretagogue candidacy.
• Critical note: If IGF-1 is already in the upper quartile, dose titration must be conservative. Your clinician will set a target ceiling — commonly 250–300 ng/mL — and monitor quarterly.

An IGF-1 test before peptides is the clinical standard. Any protocol that skips this step lacks appropriate oversight.5

Step 2: Fasting Glucose and Fasting Insulin

GH is counter-regulatory to insulin. Short-term GH elevation reduces insulin sensitivity — a known, reversible effect that resolves as the GH axis normalises.3

Before starting therapy, you need to know exactly where your glucose metabolism stands.

• Fasting glucose: Order a standard venous draw after 8–12 hours of fasting. Normal: 70–99 mg/dL. Prediabetic: 100–125 mg/dL. Diabetic: ≥126 mg/dL.
• Fasting insulin: This is frequently omitted by general practitioners and is one of the most valuable metabolic markers available. Normal fasting insulin: 2–10 µIU/mL. Elevated insulin with normal glucose is the earliest sign of insulin resistance — before HbA1c climbs.
• HOMA-IR calculation: Divide (fasting glucose × fasting insulin) by 405. A result above 1.9 indicates early insulin resistance. Above 2.9 is significant. This single number tells your clinician more about your metabolic risk than glucose alone.6

Patients with insulin resistance or prediabetes are not automatically excluded from GH peptide therapy, but their protocol requires closer glucose monitoring and potentially a lower starting dose.

Step 3: HbA1c (Glycated Haemoglobin)

HbA1c reflects your average blood glucose over the preceding 90 days. It provides a longer-term picture than fasting glucose alone.

An HbA1c above 6.5% does not rule out peptide therapy, but it changes the clinical conversation significantly. Tesamorelin, which is FDA-approved and has a robust safety profile, may be favoured in metabolically compromised patients. Read the full breakdown in the tesamorelin visceral fat review.

Step 4: Comprehensive Metabolic Panel (CMP)

The CMP covers kidney and liver function — two organ systems that are directly involved in both GH metabolism and peptide clearance.

Liver markers to review:

• ALT and AST: Elevated transaminases indicate hepatic stress. GH peptides are metabolised hepatically. Active liver disease or significantly elevated enzymes are a relative contraindication.
• Albumin and total protein: Markers of liver synthetic function and nutritional status.
• Alkaline phosphatase (ALP): Elevations may indicate biliary dysfunction.

Kidney markers:

• Creatinine and BUN: Impaired renal clearance affects how peptides and their metabolites are processed. Chronic kidney disease (CKD stage 3+) changes dosing considerably.
• eGFR: Estimated glomerular filtration rate. Below 60 mL/min/1.73m² warrants specialist input before initiating any peptide protocol.

Electrolytes:

• Sodium, potassium, and bicarbonate. GH can cause water and sodium retention. A baseline reading flags any pre-existing electrolyte imbalance.

Step 5: Full Lipid Panel

GH is a significant regulator of lipid metabolism. GH-deficient adults typically show elevated LDL cholesterol, elevated triglycerides, and reduced HDL — a pattern sometimes called the "GH-deficiency lipid signature."7

Order:

• Total cholesterol
• LDL cholesterol
• HDL cholesterol
• Triglycerides
• Non-HDL cholesterol

Baseline lipids serve two purposes. First, they may confirm suspected GH axis dysfunction. Second, they establish the benchmark against which therapeutic improvements will be measured. If you are also managing metabolic syndrome, your lipid panel is especially critical. Expect improvements in triglycerides and LDL within 12–24 weeks on a GH secretagogue protocol.8

Step 6: Thyroid Panel (TSH, Free T3, Free T4)

GH and thyroid hormones operate in close concert. GH stimulation can accelerate the conversion of inactive T4 to active T3 — sometimes unmasking subclinical hypothyroidism that was previously compensated.9

Order at minimum:

• TSH: The pituitary signal for thyroid hormone production. Elevated TSH indicates underactive thyroid. Normal: 0.4–4.0 mIU/L.
• Free T4: The precursor hormone. Normal: 0.8–1.8 ng/dL.
• Free T3: The metabolically active form. Normal: 2.3–4.1 pg/mL.

Hypothyroidism that goes undetected before starting GH peptide therapy will blunt the treatment response. Fatigue and body composition changes — often attributed to suboptimal GH — may actually be thyroid-driven. Correcting thyroid function first produces dramatically better outcomes.

Step 7: Complete Blood Count (CBC)

A full CBC is standard pre-treatment due diligence.

Check for:

• Haemoglobin and haematocrit: GH influences erythropoiesis. A pre-therapy baseline is essential, particularly in male patients where haematocrit elevation is a known side effect of hormone optimisation protocols.
• White blood cell count: An elevated WBC may indicate an active infection or inflammatory process that should be resolved before beginning therapy.
• Platelets: Standard safety check.

Step 8: Sex Hormones (Testosterone, Estradiol, DHEA-S, LH, FSH)

GH operates within a broader hormonal network. In male patients, low testosterone and low GH often co-occur — both are part of the age-related decline in anabolic signalling. In women, particularly those entering perimenopause, oestrogen decline interacts directly with GH secretion patterns.10

For men:

• Total testosterone, free testosterone, estradiol (E2), LH, FSH, SHBG. If you suspect andropause, Meto's andropause assessment can guide next steps.

For women:

• Estradiol, progesterone, LH, FSH, DHEA-S, testosterone. PMOS (previously PCOS) and perimenopause both alter GH pulsatility. Confirm hormonal status before titrating GH-stimulating peptides.

Step 9: Cortisol (Morning Serum)

Chronic cortisol elevation suppresses GH secretion — directly and significantly. A morning cortisol draw (7–9 AM, before eating) tells your clinician whether HPA axis dysregulation is undermining your GH axis before therapy even begins.

Normal morning cortisol: 6–23 µg/dL. Values persistently above 20 µg/dL alongside low IGF-1 suggest chronic stress physiology as the primary driver — and lifestyle or pharmacological intervention to lower cortisol should precede, or accompany, GH peptide therapy.

How to Read Your Results: A Practical Reference Table

This is a clinical guide, not a diagnostic tool. Your results require interpretation by a qualified clinician in the context of your full symptom history.

What Happens After Baseline Labs: Monitoring During Therapy

Baseline labs for GH peptides are the start, not the finish. Once therapy begins, your biomarkers change — and they need to be tracked.

Standard monitoring protocol:

1. IGF-1 at 6–8 weeks. This is the primary titration marker. If IGF-1 has not moved into the lower-to-mid therapeutic range, dose or timing adjustments are warranted.
2. Fasting glucose and insulin at 8–12 weeks. Confirm that GH-mediated insulin resistance has not worsened glucose control.
3. Full panel at 12 weeks. Lipids, liver enzymes, thyroid, CBC — compare directly to baseline.
4. Ongoing IGF-1 every 3–6 months. Maintenance monitoring to confirm sustained therapeutic IGF-1 and avoid supraphysiological elevation.

Want to see what these biomarker trajectories look like in practice? The 12-week GH peptide therapy results case study documents week-by-week IGF-1, HOMA-IR, triglycerides, and fasting insulin changes in a real metabolic patient.

Growth Hormone Peptide Therapy Labs: How to Order Yours

Most primary care physicians do not routinely order this panel together. You may need to advocate for specific tests — or use a platform that has already built it into the clinical workflow.

Option 1: Request from your primary care provider. Ask specifically for: IGF-1, fasting glucose, fasting insulin, HbA1c, CMP, lipid panel, TSH/Free T3/Free T4, CBC, sex hormone panel, and morning cortisol. Bring this list. Not all providers will be familiar with the peptide therapy context, so be explicit about your goal.

Option 2: Order through Meto's diagnostic panel. Meto offers structured metabolic and hormonal lab panels reviewed by clinicians who understand how to interpret results in the context of peptide therapy candidacy. You get a personalised report, clinician review, and clear next-step recommendations — without navigating the ordering process yourself.

Order your IGF-1 and metabolic baseline through Meto →

Before choosing a provider for ongoing peptide therapy, review the 2026 peptide therapy provider comparison to understand what clinical oversight standards a legitimate clinic must meet.

Conclusion

The difference between peptide therapy that works and peptide therapy that wastes your time — or causes harm — often comes down to what happened before the first injection. Growth hormone peptide therapy labs are not bureaucratic box-ticking. They are the clinical foundation that makes everything downstream more accurate, more effective, and safer.

Order your full panel. Review results with a clinician who understands the GH axis. Establish your baseline. Then start therapy with a protocol built on data, not guesswork.

If you are unsure where to begin, Meto's metabolic baseline panel covers the core biomarkers and connects you with a clinician who can interpret your results in the context of peptide therapy.

Frequently Asked Questions

What is the most important lab to get before starting growth hormone peptide therapy?

IGF-1 is the single most critical test. It is the primary downstream marker of GH activity and tells your clinician whether your GH axis is underperforming, within range, or already elevated. Without an IGF-1 baseline, there is no way to dose a GH secretagogue safely or track whether it is working.

Can I start GH peptide therapy if I have insulin resistance?

Yes, but with appropriate precautions. Insulin resistance is not an automatic disqualification. However, it requires a lower starting dose, closer glucose monitoring, and more frequent follow-up labs — particularly fasting insulin and HOMA-IR. Some clinicians will also adjust the peptide selection, favouring protocols with a more favourable short-term metabolic profile.

How long before starting peptide therapy should I get my baseline labs?

Ideally within 4–6 weeks of starting therapy. Lab values can shift with changes in diet, stress, sleep, or illness. A baseline drawn more than 8–12 weeks before therapy begins may not accurately reflect your metabolic state at the time you start treatment.

Do I need to fast before my baseline labs?

Yes, for most of the panel. Fasting glucose, fasting insulin, triglycerides, and the full lipid panel all require a minimum 8–12 hour overnight fast. TSH, IGF-1, and CBC do not strictly require fasting, but drawing everything in a single morning fasted appointment simplifies logistics and prevents having to repeat the draw.

Will my IGF-1 results be covered by insurance?

Coverage varies. IGF-1 testing is typically reimbursed when ordered in the context of a documented clinical indication — such as symptoms consistent with GH insufficiency or growth disorders. Ordering it as part of a wellness or optimisation protocol may not be covered. Meto's lab panels offer transparent self-pay pricing when insurance does not apply.

How often should I recheck labs after starting GH peptide therapy?

At minimum: IGF-1 at 6–8 weeks, a metabolic panel at 12 weeks, and a full repeat of the baseline panel at 6 months. Your clinician may accelerate this schedule if your initial IGF-1 response is strong, if glucose markers shift, or if you are on a stacked protocol with multiple peptides.