What laboratory tests should be monitored for a patient starting or already on semaglutide (GLP-1 receptor agonist), considering their individual medical history and current health status?

Laboratory Monitoring for Semaglutide Therapy

Pre-Treatment Baseline Laboratory Assessment

Before initiating semaglutide, obtain baseline metabolic parameters including HbA1c, fasting glucose, comprehensive metabolic panel with renal function (eGFR), and lipid panel to establish cardiovascular risk and monitor improvement. 1

Essential Pre-Treatment Labs:

• HbA1c and fasting glucose to establish baseline glycemic control 2
• Comprehensive metabolic panel including serum creatinine and eGFR to assess renal function 1
• Lipid panel (total cholesterol, LDL, HDL, triglycerides) to assess baseline cardiovascular risk 2
• Liver function tests (ALT, AST) as baseline, particularly if metabolic dysfunction-associated steatotic liver disease is suspected 1, 3
• Thyroid function screening is not routinely required unless clinically indicated, though semaglutide is contraindicated with personal or family history of medullary thyroid cancer 1, 2

Ongoing Monitoring During Treatment

Glycemic Monitoring Schedule

Assess glycemic status (HbA1c or continuous glucose monitoring metrics) at least quarterly during the first year and as needed when therapy changes, then at least twice yearly once stable glycemic control is achieved. 1

• HbA1c every 3 months after initiating or escalating doses until glycemic targets are achieved 1, 2
• Self-monitoring of blood glucose should be performed closely during the first 3-4 weeks, particularly if taking concomitant insulin or sulfonylureas due to hypoglycemia risk 1, 4
• Once at maintenance dose and stable, HbA1c every 3-6 months is appropriate 1, 2

Renal Function Monitoring

Monitor eGFR when initiating or escalating doses, or in patients with adverse gastrointestinal reactions, as severe GI effects can lead to volume depletion and acute kidney injury. 1

• No dose adjustment is required for semaglutide across all stages of chronic kidney disease, including eGFR <30 mL/min/1.73 m² 1
• Renal function should be checked in the first several weeks of therapy, particularly in patients with baseline renal impairment 1
• Monitor for volume depletion signs, especially in elderly patients or those on diuretics 1

Metabolic and Cardiovascular Parameters

Monitor weight, blood pressure, and lipid profiles every 3-4 months during dose titration, then at least quarterly after reaching maintenance dose. 2

• Body weight every 4 weeks during titration phase 2, 5
• Blood pressure monitoring as weight loss may necessitate antihypertensive medication adjustment 2
• Lipid panel reassessment at 3-6 months to evaluate improvements in total cholesterol, triglycerides, and LDL 2, 3
• Serum uric acid may decrease with treatment 3

Liver Function Monitoring

For patients with suspected or known metabolic dysfunction-associated steatotic liver disease, monitor liver enzymes (ALT, AST) at baseline and periodically during treatment. 1, 3

• Semaglutide may improve liver function parameters in patients with MASLD 1, 3
• No routine liver function monitoring is required in patients without liver disease 1

Special Monitoring Situations

Patients on Concomitant Insulin or Sulfonylureas

Monitor blood glucose more closely during dose adjustment to prevent hypoglycemia, particularly if treated with insulin or sulfonylureas, as these medications increase hypoglycemia risk when combined with semaglutide. 1, 4, 5

• Consider reducing basal insulin by 20% when initiating semaglutide 1, 2
• Reduce or discontinue sulfonylureas to prevent hypoglycemia 1, 2

Patients with Cardiovascular Disease

For patients with established cardiovascular disease, semaglutide provides proven cardiovascular benefit beyond glycemic control, making regular cardiovascular risk factor monitoring essential. 1, 2

• Monitor cardiovascular risk factors including blood pressure, lipids, and inflammatory markers 2
• No specific cardiac biomarker monitoring is routinely required 1

Safety Monitoring

Gastrointestinal Symptoms

Evaluate gastrointestinal symptoms at each visit during dose escalation, as nausea, vomiting, and diarrhea are common but typically mild-to-moderate and transient. 1, 4, 2

• Monitor for signs of pancreatitis (persistent severe abdominal pain) and discontinue if suspected 1, 2
• Monitor for gallbladder disease symptoms (right upper quadrant pain, jaundice) 1, 2

Nutritional Status

Monitor nutritional status and signs of malnutrition, particularly in patients experiencing significant gastrointestinal side effects or rapid weight loss. 2

Common Pitfalls to Avoid

• Do not delay follow-up beyond 3-6 months in the maintenance phase, as this may miss treatment failure or adverse effects 2
• Do not ignore volume depletion signs in elderly patients or those on diuretics, as GI effects can lead to dehydration 1
• Do not overlook hypoglycemia risk when semaglutide is combined with insulin or sulfonylureas—proactive dose reduction of these agents is essential 1, 4
• Do not wait for symptoms to check renal function in patients with baseline impairment or severe GI effects 1