Lab Work Before Peptides: What We Order and Why

Before starting any peptide protocol, we order a baseline panel of laboratory tests. The specific panel varies based on what the patient is starting and what they have brought to us, but a foundational set of tests applies to almost every new patient. This is not a marketing exercise or an attempt to generate revenue — it is the basic medical workup that responsible peptide prescribing requires.

This article walks through what we typically order, what each test tells us, and how the results affect prescribing decisions. The goal is to demystify the process and help patients understand why baseline labs matter before peptide therapy begins.

The foundational panel

Almost every new patient at The Tide has the following labs drawn at baseline:

Comprehensive Metabolic Panel (CMP). This 14-test panel includes electrolytes (sodium, potassium, chloride, bicarbonate), kidney function markers (BUN, creatinine, eGFR), liver function tests (AST, ALT, alkaline phosphatase, total protein, albumin, total bilirubin), and glucose. The CMP provides a basic picture of organ function and identifies any acute issues that would affect peptide prescribing.

Hemoglobin A1c. A measure of average blood glucose over the previous 90 days. Essential for evaluating metabolic status and identifying prediabetes or undiagnosed diabetes. Critical baseline before any GLP-1 medication.

Lipid panel. Total cholesterol, LDL cholesterol, HDL cholesterol, and triglycerides. Important for cardiovascular risk assessment and for tracking metabolic improvements during therapy.

Complete Blood Count (CBC). Red blood cells, white blood cells, platelets, and related indices. Identifies anemia, infection patterns, or platelet abnormalities that would affect care.

TSH (thyroid stimulating hormone). The screening test for thyroid function. Many patients with metabolic concerns or fatigue have unrecognized thyroid dysfunction that should be addressed before attributing symptoms to other causes.

Vitamin D (25-hydroxy). Vitamin D deficiency is extraordinarily common, affects multiple systems relevant to peptide therapy, and is easily correctable.

This foundational panel costs relatively little and provides the basic context for any peptide therapy decision.

Additional labs based on clinical scenario

Specific peptide protocols and patient scenarios call for additional baseline labs:

For GLP-1 medication candidates: we add fasting insulin (helpful for evaluating insulin resistance), and we screen for personal or family history of medullary thyroid cancer or MEN-2 syndrome (these are contraindications to GLP-1 medications).

For GH-axis protocol candidates: we add IGF-1, which is the primary marker we use to evaluate GH-axis function. Optionally, IGFBP-3 provides additional context. We document the IGF-1 level relative to age-appropriate reference range.

For male patients with hormonal concerns: we add total and free testosterone (drawn between 7-10 AM for accurate values), estradiol (using a sensitive assay appropriate for men), prolactin, LH, FSH, and PSA (in age-appropriate patients).

For female patients with hormonal concerns: we add estradiol, progesterone (timing-dependent based on menstrual status), DHEA-S, prolactin, LH, and FSH.

For recovery and tendon protocol candidates: we may add C-reactive protein, ESR, and other inflammatory markers, particularly if there is a history of chronic inflammation or autoimmune patterns.

For immune-focused protocol candidates: we add quantitative immunoglobulins, lymphocyte subsets, and other immune markers based on the specific clinical concern.

For longevity-focused patients: we may add hsCRP, homocysteine, ApoB, lipoprotein(a), and other markers that provide additional information about cardiovascular and metabolic aging.

Why this matters before peptides

Several reasons make baseline labs essential rather than optional:

Identifying contraindications. Some peptide therapies are contraindicated in specific lab scenarios. GLP-1 medications should not be started in patients with personal or family history of medullary thyroid cancer. GH-axis protocols are problematic in patients with active diabetic retinopathy, severely uncontrolled diabetes, or significantly elevated cancer risk markers. Discovering these contraindications after starting therapy is much worse than discovering them before.

Ruling out competing diagnoses. Patients often arrive attributing symptoms to one cause when the actual cause is something different. Fatigue attributed to “low GH” may turn out to be undiagnosed thyroid disease, anemia, or sleep apnea. Weight gain attributed to “metabolism” may have a thyroid or endocrine basis. Identifying the actual cause and treating it directly is better than starting peptide therapy on top of an unaddressed underlying issue.

Establishing comparison values. Future labs are most useful when compared against baseline. Without baseline values, we cannot tell whether a finding at follow-up represents a change from baseline or has been present all along.

Optimizing the foundation. Many patients have correctable issues that affect peptide therapy outcomes — vitamin D deficiency, suboptimal thyroid function, iron deficiency, insulin resistance — that should be addressed alongside or before starting peptides. Identifying these requires lab work.

Documenting clinical legitimacy. Responsible peptide prescribing involves documented medical decision-making based on objective data. The baseline panel documents the medical context for the prescription, which matters for both patient care quality and regulatory legitimacy.

What we do with the results

The baseline lab review is its own clinical visit. We walk through each result with the patient, explain what each test is measuring, identify abnormal results, discuss what additional workup may be warranted, and adjust the planned peptide protocol based on findings.

Common scenarios we encounter:

Patient with elevated HbA1c but no prior diabetes diagnosis. We discuss the prediabetes or diabetes finding, recommend appropriate primary care follow-up if needed, and consider whether GLP-1 therapy should target the metabolic dysfunction or whether other approaches should be primary.

Patient with low IGF-1 and significant fatigue. Before attributing the fatigue to GH-axis decline, we work through other potential causes — sleep, thyroid, iron status, mood, current medications. If GH-axis decline appears to be a meaningful contributor and other causes have been addressed, we proceed with appropriate GH peptide support.

Patient with elevated PSA at baseline. A PSA above the age-appropriate normal range warrants urology evaluation before starting any GH-axis or testosterone-related therapy. We refer for evaluation and defer prescribing until the urology workup is complete.

Patient with low vitamin D and other suboptimal markers. We address the vitamin D deficiency and discuss the foundational interventions that might improve the other markers before adding peptide therapy on top.

Patient with significantly abnormal CBC. Anemia, unexplained leukocytosis, or significant platelet abnormalities warrant primary care or hematology workup before starting any peptide therapy.

Follow-up labs

Initial follow-up labs typically occur at 90 days for most peptide protocols. The specific panel depends on the therapy:

For GLP-1 patients: CMP, HbA1c, lipid panel, weight, and patient-reported tolerability. We expect modest improvements in metabolic markers and stable or improved liver function.

For GH-axis patients: IGF-1 (the primary monitoring lab), CMP, fasting glucose, and patient-reported outcomes. We adjust dosing based on IGF-1 trajectory.

For male hormone optimization: total and free testosterone, estradiol, hematocrit (which can rise on testosterone therapy and requires monitoring), PSA, lipid panel.

For recovery and immune protocols: targeted labs based on the specific clinical scenario and what changes we expect.

Subsequent labs follow at 6 months and then annually for stable patients on long-term protocols, with earlier follow-up if clinical scenarios change.

What patients should bring

If you have recent labs, bring them. Labs from the past 6 months are usually sufficient if reasonably comprehensive. We try to avoid redundant testing — you should not need to repeat labs that have been done recently and are still clinically valid.

Bring information about current medications, supplements, and any prior peptide use. Some medications affect lab interpretation (for example, certain medications affect testosterone or thyroid measurements), and prior peptide use affects how we interpret current values.

Bring information about prior diagnoses, family history (particularly for cancer history relevant to peptide prescribing), and any specific concerns you want addressed. The lab panel can be customized based on your specific situation.

The cost question

Lab costs vary by location and insurance status. The foundational panel can typically be completed for $150-300 if not covered by insurance, depending on which specific tests are included. We work with patients on cost considerations and can prioritize testing if needed.

Some patients ask whether they can skip the baseline labs to save money. Our position is that this is not a savings — it is a deferral of cost combined with substantially worse clinical care. Starting peptide therapy without appropriate baseline workup means we cannot identify contraindications, cannot rule out competing diagnoses, cannot establish comparison values, and cannot make informed dosing decisions. The downstream costs of poor prescribing decisions usually exceed the upfront cost of appropriate workup.

Bottom line

Baseline labs are not optional or padding. They are the foundation of responsible peptide prescribing. The specific panel varies based on the planned therapy and patient situation, but the principle is consistent: we make prescribing decisions based on objective data, not on patient self-report alone.

If a clinic offers peptide therapy without baseline lab work, that is a serious quality concern. If a clinic orders labs but does not review them carefully with you and explain the results, that is a smaller but still meaningful concern. The lab review and the clinical conversation around it are part of what you should expect from quality peptide care.