Which Labs Are Needed Before My Clinician Visit? | Calibrate

Why Calibrate Requires Pre-Visit Labs

Calibrate's clinicians prescribe GLP-1 receptor agonists, such as semaglutide and tirzepatide, to patients pursuing metabolic health goals. These medications interact directly with glucose regulation, kidney clearance, thyroid tissue, and lipid metabolism, which is why your clinician cannot safely assess your eligibility from a health history questionnaire alone.

A complete pre-visit lab panel gives your clinician a biological baseline. That baseline does three things: it confirms you meet eligibility criteria, it screens for contraindications that could make certain medications unsafe, and it gives both you and your care team a reference point for tracking change over time.

The Legal and Clinical Standard Behind the Requirement

The FDA label for semaglutide 2.4 mg (Wegovy) lists a personal or family history of medullary thyroid carcinoma as a contraindication, and thyroid C-cell tumors were observed in rodent studies at clinically relevant exposures (FDA prescribing information, Wegovy). The prescribing information for tirzepatide (Zepbound) carries an identical boxed warning (FDA prescribing information, Zepbound). Ordering a TSH before each visit does not screen for those tumors directly, but it establishes thyroid function status and helps detect pre-existing thyroid disease that needs monitoring during therapy.

How Results Reach Your Clinician

You order labs at any CLIA-certified draw site, receive a digital copy of your results, and upload the PDF to your Calibrate portal. Your clinician reviews the panel during your video appointment. If results are missing, the appointment is typically rescheduled. Plan to get labs drawn at least 48 to 72 hours before your visit to allow time for processing and upload.

The Full Pre-Visit Lab Panel, Explained Test by Test

The standard Calibrate pre-visit panel includes six categories of markers. Each one answers a specific clinical question.

1. Thyroid-Stimulating Hormone (TSH)

TSH is secreted by the pituitary gland and tells the thyroid to produce thyroxine (T4) and triiodothyronine (T3). A high TSH signals the pituitary is working harder than normal to compensate for an underactive thyroid. A suppressed TSH suggests the thyroid may be overactive or that a patient is on excess thyroid hormone replacement.

The American Thyroid Association defines the laboratory reference interval as approximately 0.4 to 4.0 mIU/L, though individual labs vary slightly (American Thyroid Association guidelines). Uncontrolled hypothyroidism causes weight gain, fatigue, and dyslipidemia that can be misattributed to lifestyle factors. Confirming thyroid function before starting a GLP-1 program prevents that misattribution and ensures any thyroid disorder is treated in parallel.

TSH alone is usually sufficient at baseline. Free T4 may be added if TSH is outside the reference range, per your clinician's judgment.

2. Hemoglobin A1c (HbA1c)

HbA1c reflects average blood glucose over the preceding 8 to 12 weeks by measuring the percentage of hemoglobin molecules that have glucose attached. The American Diabetes Association classifies HbA1c <5.7% as normal, 5.7 to 6.4% as prediabetes, and 6.5% or above as diabetes (ADA Standards of Care 2024).

This single marker directly affects which GLP-1 formulation your clinician may prescribe. Semaglutide 0.5 to 2 mg (Ozempic) is FDA-approved for type 2 diabetes management, while semaglutide 2.4 mg (Wegovy) is approved for chronic weight management in adults with BMI >30 or BMI >27 with at least one weight-related comorbidity. A patient with an HbA1c of 7.2% has diabetes, not simply obesity, and the clinical plan differs accordingly.

In STEP-1 (N=1,961), participants without diabetes who received semaglutide 2.4 mg achieved a mean weight loss of 14.9% at 68 weeks versus 2.4% with placebo (Wilding JPC et al., NEJM 2021). Baseline HbA1c was one of the covariates tracked to ensure uniform reporting across subgroups.

3. Fasting Plasma Glucose

Fasting glucose gives your clinician an immediate snapshot of glucose regulation. HbA1c is the three-month average; fasting glucose is today's reading. The two together confirm or clarify each other. A fasting glucose of 126 mg/dL or above on two separate occasions meets the ADA diagnostic threshold for diabetes (ADA Standards of Care 2024).

Fasting is required. Eating within 9 to 12 hours before the draw will raise your glucose reading artificially and may cause your clinician to order a repeat test, delaying your appointment.

4. Fasting Lipid Panel

The lipid panel measures total cholesterol, LDL cholesterol, HDL cholesterol, triglycerides, and non-HDL cholesterol. Each component carries independent cardiovascular risk information.

Elevated LDL is the primary driver of atherosclerotic cardiovascular disease (ASCVD) risk in most adults. The 2018 ACC/AHA Guideline on the Management of Blood Cholesterol recommends high-intensity statin therapy for patients with LDL >190 mg/dL or established ASCVD, regardless of other risk factors (Grundy SM et al., JACC 2019). If your lipid panel reveals a value in that range, your Calibrate clinician will flag it and may recommend statin evaluation alongside your GLP-1 plan.

Triglycerides above 500 mg/dL raise the risk of pancreatitis. Because GLP-1 receptor agonists also carry a class warning about pancreatitis (though causality in humans remains unresolved), a severely elevated triglyceride level at baseline changes the risk-benefit discussion your clinician has with you before prescribing.

HDL below 40 mg/dL in men or below 50 mg/dL in women is considered low per ATP III criteria and contributes to overall ASCVD risk scoring. Your clinician uses the full panel together, not any single number in isolation.

5. Comprehensive Metabolic Panel (CMP)

The CMP is a 14-marker blood test that covers two organ systems your clinician must assess before prescribing a GLP-1 receptor agonist.

Kidney function markers. Serum creatinine, blood urea nitrogen (BUN), and the calculated estimated glomerular filtration rate (eGFR) tell your clinician how well your kidneys filter waste. Semaglutide does not require renal dose adjustment, but kidney disease affects overall cardiovascular risk and can influence how aggressively your clinician treats other metabolic factors. An eGFR below 30 mL/min/1.73m² would prompt a more detailed nephrology conversation before starting any new medication.

Liver function markers. Alanine aminotransferase (ALT) and aspartate aminotransferase (AST) are enzymes released when liver cells are damaged. Non-alcoholic fatty liver disease (NAFLD) affects a significant proportion of patients seeking weight management care. In a 2023 phase 3 trial (SURMOUNT-1, N=2,539), tirzepatide 15 mg produced 20.9% mean body weight reduction at 72 weeks, with concurrent improvements in liver enzyme levels (Jastreboff AM et al., NEJM 2022). Knowing your baseline ALT and AST lets your clinician track whether those values improve during treatment, as expected, or worsen unexpectedly.

Electrolytes and glucose. The CMP also includes sodium, potassium, chloride, carbon dioxide (bicarbonate), and fasting glucose (overlapping with the standalone glucose order). These confirm acid-base balance and electrolyte status that can be disrupted by significant caloric restriction during the program.

6. Complete Blood Count (CBC)

The CBC measures red blood cells, white blood cells, and platelets. It screens for anemia, infection, and clotting disorders.

Anemia is especially relevant here. Iron-deficiency anemia and hypothyroidism share overlapping symptoms, including fatigue and cold intolerance. A low hemoglobin or hematocrit at baseline explains symptoms that might otherwise be misattributed to caloric restriction once the program begins. Your clinician can then recommend iron supplementation or further workup rather than adjusting your GLP-1 dose unnecessarily.

White blood cell count helps screen for active infection or immune dysregulation. Clinicians prefer to start a new metabolic medication regimen when the patient is at stable baseline health rather than during an acute illness.

How to Prepare for Your Lab Draw

Getting accurate results requires straightforward preparation. These points apply to the full panel.

Fasting Protocol

Fast for 9 to 12 hours before your blood draw. Water and plain black coffee (no cream or sugar) are generally acceptable for the glucose and lipid portions, but confirm with your draw site. Many patients schedule early-morning appointments to make fasting easier.

Medication Timing

Do not stop any prescribed medication before your labs unless your Calibrate clinician has explicitly told you to. Thyroid hormone replacement (levothyroxine), statins, and antidiabetic agents should be taken as usual. Biotin supplements above 5 mg/day can interfere with immunoassay-based thyroid tests and may cause falsely low TSH readings. The FDA issued a safety communication on this topic in 2019 (FDA Safety Communication, 2019). Stop high-dose biotin at least 48 hours before your thyroid labs.

Timing Relative to Your Appointment

Order labs at least 5 to 7 business days before your appointment if you are using a standard commercial lab. Results from Quest or LabCorp typically return within 1 to 3 business days, but delays occur. Upload your PDF as soon as results arrive so the clinical team can flag any values that need same-day follow-up before you even enter the video call.

What Happens if a Lab Value Is Outside the Normal Range

Out-of-range values do not automatically disqualify you from the program. They change the conversation.

A Calibrate clinician uses the following decision logic when reviewing your panel before your visit:

• TSH above 4.0 mIU/L: Order free T4, refer to or coordinate with a thyroid specialist, and discuss whether starting levothyraxine first is appropriate before adding a GLP-1 agent.
• HbA1c 6.5% or above: Confirm diabetes diagnosis, consider whether an FDA-approved diabetes indication (semaglutide 0.5 to 2 mg, tirzepatide 5 to 15 mg) is more appropriate than the weight-management indication.
• LDL above 190 mg/dL: Flag for statin evaluation, document ASCVD risk score using the Pooled Cohort Equations, and potentially co-manage with your primary care physician.
• ALT or AST more than 3 times the upper limit of normal: Pause GLP-1 initiation, order hepatitis B and C serology, and pursue further hepatology evaluation.
• eGFR below 30 mL/min/1.73m²: Nephrology referral before initiating new metabolic therapy; SGLT-2 co-prescription is contraindicated at that eGFR level.
• Hemoglobin below 10 g/dL: Investigate underlying cause (iron, B12, folate deficiency) before starting the program.

The goal is not to exclude patients but to ensure the program is safe and structured correctly from the first prescription.

Repeat Labs During the Program

Pre-visit labs are not a one-time event. Calibrate typically schedules repeat metabolic panels at 3-month intervals to track program response and monitor for any medication-related changes.

What Gets Tracked Over Time

HbA1c and fasting glucose confirm glycemic response to both the medication and dietary changes. Lipid panels track LDL and triglyceride changes, since GLP-1 receptor agonists have shown modest LDL reductions and more pronounced triglyceride reductions in clinical data. In the LEADER trial (N=9,340), liraglutide reduced triglycerides and produced small but consistent improvements in LDL versus placebo over 3.8 years (Marso SP et al., NEJM 2016).

TSH is typically rechecked at 6 months if the baseline was normal, or sooner if symptoms of thyroid dysfunction emerge (unexplained weight plateau, new palpitations, cold intolerance, or heat intolerance).

How to Interpret Improving vs. Worsening Values

A drop in HbA1c from 6.1% to 5.7% after 12 weeks is a measurable clinical response, not just a number. It indicates the medication, dietary changes, or both are improving glucose regulation at a cellular level. Your clinician documents these changes and uses them to adjust dose titration plans. Dose escalation from semaglutide 1.7 mg to 2.4 mg weekly, for example, may be more aggressive if early metabolic markers are improving rapidly and side effects remain manageable.

An unexpected rise in ALT or AST after starting the medication prompts a dose hold and repeat testing. These situations are uncommon in clinical practice but are precisely why baseline values matter. Without a pre-visit lab, your clinician cannot distinguish a new drug effect from a pre-existing liver condition.

Thyroid Health as a Specific Focus Before GLP-1 Therapy

Thyroid status deserves particular attention in any weight management program. Subclinical hypothyroidism, defined as a TSH between 4.0 and 10.0 mIU/L with normal free T4, is present in approximately 4 to 8% of the general population and up to 15 to 18% of older women (Garber JR et al., Thyroid 2012). Many patients seeking weight management care have never had their thyroid tested.

The American Thyroid Association's 2012 guideline states: "We recommend treating hypothyroidism in all patients with serum TSH greater than 10 mIU/L." For TSH values between 4.0 and 10 mIU/L, treatment decisions depend on symptoms, antibody status, and cardiovascular risk (Garber JR et al., Thyroid 2012).

Why Untreated Hypothyroidism Reduces GLP-1 Effectiveness

An underactive thyroid slows basal metabolic rate, impairs lipid clearance, and causes fluid retention, all of which counteract the caloric-deficit mechanisms that GLP-1 receptor agonists rely on. A patient with an undetected TSH of 8.5 mIU/L starting semaglutide may see blunted weight loss, not because the medication is failing but because a competing metabolic disease is untreated. Identifying and correcting this before the first prescription prevents both therapeutic frustration and unnecessary dose escalation.

Thyroid Antibodies and Autoimmune Risk

If your TSH is elevated at baseline, your Calibrate clinician may also order thyroid peroxidase antibodies (TPO-Ab) and thyroglobulin antibodies (TG-Ab). Positive antibodies in the setting of a high TSH confirm Hashimoto thyroiditis, the most common cause of hypothyroidism in the United States. This diagnosis does not prevent GLP-1 prescribing but does require parallel thyroid management, usually levothyraxine titrated to bring TSH below 2.5 mIU/L before initiating metabolic therapy.

Interpreting Your Results Before Your Appointment

Your lab report will arrive as a PDF with each value listed alongside a lab-specific reference range. Do not compare your result to a reference range from a different lab system, since instruments and calibrators vary by facility.

Focus on flagged values, marked "H" (high) or "L" (low) on most reports. Write down specific questions for your clinician: not "my cholesterol looks bad" but "my LDL is 172 mg/dL and my 10-year ASCVD risk was estimated at 9.4% on the AHA calculator, so should I be on a statin before starting semaglutide?"

That level of specificity moves the appointment from a generic intake conversation to a productive clinical dialogue.

Bring or upload the complete lab report, not just the one-page summary some portals generate. Your clinician needs the individual component values with reference ranges, not a traffic-light summary.

Commonly Asked Questions About Calibrate Pre-Visit Labs