What labs should be drawn on a female patient who has stalled with weight loss on a Glucagon-like peptide-1 (GLP-1) receptor agonist?

Laboratory Evaluation for Female Patients with Weight Loss Stalls on GLP-1 Receptor Agonists

A comprehensive metabolic panel (CMP), estimated glomerular filtration rate (eGFR), lipid profile, and hemoglobin A1C should be drawn for female patients who have stalled with weight loss on GLP-1 receptor agonists. 1

Core Laboratory Tests

Based on the 2024 DCRM 2.0 guidelines, the following laboratory tests are recommended:

• Comprehensive Metabolic Panel (CMP) 1

  • Glucose
  • Electrolytes (sodium, potassium, chloride, carbon dioxide)
  • Kidney function (BUN, creatinine)
  • Liver function (ALP, ALT, AST, bilirubin)
  • Proteins (albumin, total protein)
  • Calcium

• Estimated Glomerular Filtration Rate (eGFR) 1

• Plasma Lipids 1

• Hemoglobin A1C 1

Additional Tests to Consider

For patients experiencing weight loss plateaus specifically, consider adding:

• Thyroid Function Tests (TSH, Free T4)

  • Thyroid dysfunction can impact metabolism and weight management

• Sex Hormone Panel

  • Particularly important for female patients as hormonal imbalances can affect weight regulation 2
  • Consider testing for PCOS markers if clinically indicated (testosterone, DHEA-S, LH/FSH ratio)

• Inflammatory Markers

  • C-reactive protein (CRP)
  • ESR (erythrocyte sedimentation rate)
  • Chronic inflammation may impede weight loss efforts

Monitoring for GLP-1 RA Side Effects

Since GLP-1 RAs can cause specific side effects that might impact weight loss:

• Gallbladder Function Tests

  • GLP-1 RAs have been associated with gallbladder disorders 1
  • Consider ultrasound if symptoms suggest cholelithiasis

• Pancreatic Enzymes

  • Monitor for acute pancreatitis risk 1
  • Amylase and lipase if clinically indicated

Interpreting Results

When evaluating laboratory results:

1. Glycemic Control

   • Assess if A1C has improved or plateaued
   • GLP-1 RAs should improve glycemic control alongside weight loss

2. Metabolic Parameters

   • Evaluate for improvements in lipid profile
   • Check liver function as fatty liver may improve with weight loss

3. Medication Interactions

   • Review if patient is on medications that may promote weight gain (antidepressants, antipsychotics, antiepileptics, β-blockers, corticosteroids) 1
   • These medications may counteract the weight loss effects of GLP-1 RAs

Clinical Pitfalls to Avoid

• Don't overlook body composition changes

  • Weight stalls may reflect lean mass preservation while fat mass continues to decrease 3
  • Consider body composition analysis if available

• Beware of medication adherence issues

  • Missed doses can affect efficacy
  • GLP-1 RAs require consistent administration for optimal effect 1

• Consider GLP-1 RA dose adequacy

  • Some patients may require dose titration to achieve continued weight loss 1
  • Submaximal dosing may lead to weight loss plateaus

• Assess for gastric emptying effects

  • GLP-1 RAs delay gastric emptying, which may affect medication absorption 1
  • This effect can diminish over time (tachyphylaxis) and potentially impact weight loss

By systematically evaluating these laboratory parameters and clinical factors, you can better identify potential causes for weight loss stalls and develop targeted interventions to help your female patient resume her weight loss journey.