What baseline laboratory tests are required before initiating Mounjaro (tirzepatide) therapy?

Initial Laboratory Testing Before Starting Mounjaro (Tirzepatide)

Before initiating Mounjaro therapy, obtain fasting blood glucose or HbA1c, comprehensive metabolic panel with liver function tests, lipid profile, body mass index, and pregnancy test in women of childbearing potential. 1

Required Baseline Laboratory Tests

Glycemic Assessment

• Fasting blood glucose or HbA1c to establish baseline glycemic status and assess diabetes risk 1
• This provides the critical baseline for monitoring therapeutic response to tirzepatide 1

Metabolic Panel

• Comprehensive metabolic panel including liver function tests (ALT, AST, alkaline phosphatase, bilirubin) to evaluate baseline hepatic function 1
• This is essential as GLP-1/GIP receptor agonists can affect metabolic parameters 1

Lipid Assessment

• Lipid profile (total cholesterol, LDL, HDL, triglycerides) to establish baseline values, as tirzepatide affects lipid metabolism 1

Anthropometric Measurements

• Body mass index (BMI) and waist circumference must be documented at baseline, as weight loss is a primary therapeutic effect 1
• These measurements are critical for tracking the substantial weight reduction seen with tirzepatide (5.4-11.7 kg in clinical trials) 2

Reproductive Health Screening

• Pregnancy test for all women of childbearing potential before initiating therapy 1
• This is mandatory given the lack of safety data in pregnancy 1

Critical Safety Screening (Not Laboratory-Based)

Black Box Warning Assessment

• Screen for personal or family history of medullary thyroid carcinoma or multiple endocrine neoplasia type 2, as tirzepatide carries this black box warning 1
• This is an absolute contraindication to therapy 1

Pancreatitis History

• Carefully evaluate history of pancreatitis, as GLP-1/GIP receptor agonists may increase pancreatitis risk 1

Post-Initiation Monitoring Schedule

First 3 Months (Intensive Phase)

• BMI measurement monthly to detect early weight changes 1
• Blood pressure monitoring at each visit during initial treatment phase 1

After 3 Months (Maintenance Phase)

• BMI measurement quarterly 1
• Blood pressure, fasting glucose, and lipids reassessed at 3 months, then yearly thereafter 1

Common Pitfalls to Avoid

• Failure to obtain baseline values makes it impossible to determine whether metabolic improvements or abnormalities are treatment-emergent versus pre-existing 1
• Inadequate frequency of weight monitoring in the first 3 months when metabolic changes are most pronounced—tirzepatide causes unprecedented weight loss with 20.7-68.4% of patients losing >10% body weight 2
• Not screening for pregnancy before initiation in women of childbearing potential 1
• Missing the thyroid cancer screening, which would expose patients to unnecessary risk given the black box warning 1