Labs Before Starting a GLP-1
There is no single official blood panel required before starting a GLP-1 medication such as semaglutide or tirzepatide. The tests most often ordered at a baseline visit are a hemoglobin A1c, a comprehensive metabolic panel (CMP), a lipid panel, and a complete blood count (CBC), sometimes with a thyroid test (TSH). The clinician who prescribes the medication decides which tests are needed.
This page explains what each test measures, why it tends to come up before GLP-1 treatment, and what it costs if you pay cash. It is not a list of tests you should get. Your prescriber knows your history and makes that call.
What blood tests are commonly done before starting a GLP-1?
The drug labels themselves do not spell out a baseline panel. The FDA prescribing information for Wegovy (semaglutide) and Zepbound (tirzepatide) says that in people with diabetes, blood glucose should be monitored before starting and during treatment (Wegovy prescribing information, section 2.1) (Zepbound prescribing information, section 5.7). Both labels also say to monitor kidney function in people who have side effects, like vomiting or diarrhea, that could lead to dehydration (Wegovy prescribing information, section 5.5).
The usual baseline tests come from general medical evaluation guidelines instead:
- The American Diabetes Association lists an A1c, a lipid profile, liver function tests, kidney function (serum creatinine and eGFR, plus a urine albumin test), and a CBC with platelets in its initial evaluation for people with diabetes (ADA Standards of Care 2026, Section 4, Table 4.1).
- A 2023 clinical review on evaluating adults with obesity lists A1c, fasting glucose, a lipid profile, thyroid function tests, liver function tests, and a full blood count (Dobbie et al., 2023).
Most of those markers are covered by five common tests:
Hemoglobin A1c
Shows average blood sugar over the past two to three months. No fasting needed.
Cash price: $29 to $50
Comprehensive metabolic panel (CMP)
Fourteen measurements covering kidney and liver function, glucose, and electrolytes.
Cash price: $36 to $50.10
Lipid panel
Measures LDL, HDL, total cholesterol, and triglycerides. Fasting is often required.
Cash price: $29 to $59.10
TSH (thyroid)
Checks overall thyroid function. It does not screen for the C-cell tumors in the GLP-1 warning.
Cash price: $39 to $78
Complete blood count (CBC)
Counts red cells, white cells, and platelets, and measures hemoglobin.
Cash price: $28 to $44
Who decides which tests I need?
The prescribing clinician. They may order all of these tests, some of them, or different ones, depending on your health history, other medications, and any recent results you already have. Recent results from another doctor may be enough.
If you order tests yourself, bring the results to that clinician. Understanding what a result means for you is their job, not ours.
Why does the thyroid come up with GLP-1 medications?
Semaglutide and tirzepatide labels carry a boxed warning about thyroid C-cell tumors. In rodent studies, these drugs caused C-cell tumors. It is not known whether they cause these tumors, including medullary thyroid carcinoma (MTC), in people. The drugs are not to be used by anyone with a personal or family history of MTC or with Multiple Endocrine Neoplasia syndrome type 2 (MEN 2) (Wegovy prescribing information, boxed warning) (Zepbound prescribing information, boxed warning).
That warning is often confused with a TSH test, but they are different things. A TSH test measures how well the thyroid is working overall. It does not screen for C-cell tumors. The labels say routine monitoring of serum calcitonin or thyroid ultrasound is “of uncertain value” for early detection of MTC in people taking these drugs (Wegovy prescribing information, section 5.1).
TSH appears on many baseline lists because thyroid function tests are a common part of evaluating weight-related health in general (Dobbie et al., 2023). See the TSH page for more.
What about lipase, vitamin B12, or calcitonin?
You may see these tests on some GLP-1 lab lists online. Here is what the sources say:
- Lipase and amylase. In clinical trials, these pancreatic enzymes rose on average in people taking semaglutide or tirzepatide. The labels say the meaning of these increases is unknown when there are no other signs of pancreatitis (Wegovy prescribing information, section 6.1) (Zepbound prescribing information, section 6.1). Neither label lists them as a routine baseline test.
- Vitamin B12. The ADA ties periodic B12 testing to long-term use of metformin, a different diabetes medication, not to GLP-1 medications (ADA Standards of Care 2026, Section 9).
- Calcitonin. See the thyroid section above. The labels describe routine calcitonin monitoring as of uncertain value.
The ADA does advise watching nutrition during intentional weight loss, with attention to protein and micronutrient deficiencies (ADA Standards of Care 2026, Section 8, recommendation 8.14). Which tests, if any, that involves is up to the clinician.
How much does a baseline panel cost without insurance?
Ordering all five tests separately from the online providers we checked cost $164 to $267 in total, including any required fees. Prices were last checked September 23, 2026.
| Test | Walk-In Lab | Personalabs | HealthLabs.com | Private MD Labs | Quest (questhealth.com) |
|---|---|---|---|---|---|
| Hemoglobin A1c | $35 | $50 | $29 | $31 | $39 |
| Comprehensive metabolic panel (CMP) | $30 | $44 | $39 | $39 | $44.10 |
| Lipid panel | $33 | $51 | $29 | $51 | $53.10 |
| TSH | $35 | $78 | $39 | $43 | $49 |
| CBC with differential and platelets | $27 | $44 | $28 | $31 | $26.10 |
| Required fee | $6* | None listed | None listed | None listed | $6* |
| All five, ordered separately | $166 | $267 | $164 | $195 | $217.30 |
Prices last checked September 23, 2026 on each company's own website. Prices change often, and sales come and go, so confirm the price at checkout. Totals add one required fee per order. *Quest showed its fee beside each test; we did not confirm whether it is charged once per order. Not checked: Labcorp OnDemand (site unavailable on the check date).
Walk-In Lab also sells a “GLP-1 Basic Blood Test Panel” for $165 plus a $6 physician fee. Its product page lists a CMP, CBC, lipid panel, A1c, TSH, and insulin (Walk-In Lab). See the cost guide for fees and what is included.
Do I need to fast before these tests?
It depends on the test. An A1c does not need fasting. A cholesterol test may need a 9 to 12 hour fast (MedlinePlus), and a CMP may need a fast of several hours (MedlinePlus). When tests are drawn together, the strictest instruction usually applies to the whole visit. Follow what the ordering provider tells you.
Where can I order these tests?
Your own doctor can order them, and so can online lab testing companies that let you buy tests directly. With the online option, a physician working with the company reviews the order, and you get your blood drawn at a Quest or Labcorp location. How ordering labs without a doctor works.
Compare the providers side by side.
Frequently asked questions
- Is bloodwork required before starting a GLP-1 medication?
- The FDA prescribing information for semaglutide (Wegovy) and tirzepatide (Zepbound) does not list a required baseline blood panel. It does say that people with diabetes should have their blood glucose monitored before and during treatment. In practice, the prescribing clinician decides which tests to order.
- Do I need to fast before GLP-1 baseline labs?
- An A1c does not require fasting. A lipid panel and a comprehensive metabolic panel may require fasting, often for 9 to 12 hours for cholesterol testing, according to MedlinePlus. Follow the instructions from whoever orders the tests.
- Does a TSH test check for the thyroid cancer risk in the GLP-1 warning?
- No. The boxed warning is about thyroid C-cell tumors, including medullary thyroid carcinoma. TSH measures overall thyroid function, not C-cell tumors. The prescribing information says routine calcitonin testing or thyroid ultrasound is of uncertain value for early detection of these tumors.
- How much does a full baseline panel cost without insurance?
- Ordering an A1c, CMP, lipid panel, TSH, and CBC separately cost between about $164 and $267 across the online providers we checked, including required fees. Prices change, so check the dated table on this page.
Sources
- WEGOVY (semaglutide) injection and tablets, Prescribing Information (revised 06/2026). Novo Nordisk / U.S. FDA. Checked September 23, 2026.
- ZEPBOUND (tirzepatide) injection, Prescribing Information (revised 08/2026). Eli Lilly / U.S. FDA. Checked September 23, 2026.
- 4. Comprehensive Medical Evaluation and Assessment of Comorbidities: Standards of Care in Diabetes 2026 (Table 4.1). American Diabetes Association, Diabetes Care 2026;49(Suppl 1):S61 to S88. Checked September 23, 2026.
- 8. Obesity and Weight Management for the Prevention and Treatment of Diabetes: Standards of Care in Diabetes 2026. American Diabetes Association, Diabetes Care 2026;49(Suppl 1). Checked September 23, 2026.
- 9. Pharmacologic Approaches to Glycemic Treatment: Standards of Care in Diabetes 2026. American Diabetes Association, Diabetes Care 2026;49(Suppl 1). Checked September 23, 2026.
- Clinical evaluation of patients living with obesity (Dobbie LJ, Coelho C, Crane J, McGowan B). Internal and Emergency Medicine, 2023. Checked September 23, 2026.
- Cholesterol Levels. MedlinePlus, U.S. National Library of Medicine. Checked September 23, 2026.
- Comprehensive Metabolic Panel (CMP). MedlinePlus, U.S. National Library of Medicine. Checked September 23, 2026.
- GLP-1 Basic Blood Test Panel. Walk-In Lab. Checked September 23, 2026.