• Assess patient for signs and symptoms of acromegaly (ring size, soft-tissue swelling, arthralgia, headache, perspiration, fatigue) periodically during therapy.
• Monitor patient for signs and symptoms or hepatitis or other liver injury (jaundice, hyperbilirubinemia, fatigue, nausea, vomiting, right upper quadrant pain, ascites, unexplained edema, easy bruising). If these occur, immediately perform a comprehensive hepatic work-up; may require discontinuation.
• Monitor for signs and symptoms of systemic hypersensitivity reactions (anaphylactic reactions, laryngospasm, angioedema, generalized skin reactions, rash, erythema, pruritus, urticaria) during therapy. Symptoms may not occur after re-challenge.

Lab Test Considerations:

• Monitor serum IGF-1 levels 4–6 wk after therapy is initiated or any dose adjustments are made and at least every 6 mo after IGF-1 levels have normalized. Levels should be maintained within the age-adjusted normal range.
  • Monitor serum glucose carefully in patients with insulin-dependent diabetes; may increase glucose tolerance causing hypoglycemia, requiring decrease in dose of antidiabetic medications.
  • Measure liver tests (serum ALT, AST, total bilirubin and alkaline phosphatase levels) at baseline. If normal: Monitor liver tests monthly during first 6 mo of treatment, quarterly for next 6 mo, and biannually for the next year. If liver tests are elevated, but ≤3 times the upper limit of normal: Monitor liver tests monthly for at least 1 year after initiation of therapy and biannually for the next year. If >3 times the upper limit of normal: Do not treat with pegvisomant until a comprehensive work-up establishes the cause of liver dysfunction. If pegvisomant is used, monitor liver tests very closely.
  • If patient develops liver test elevations or other signs or symptoms of liver dysfunction during therapy, monitor as follows: If ≥3 but <5 times the upper limit of normal, without signs or symptoms of hepatitis or other liver injury, or ↑ in serum total bilirubin: May continue therapy, but monitor liver tests weekly and perform a comprehensive work-up to determine if alternative cause of liver dysfunction is present. If liver tests are >5 times the upper limit of normal or AST and ALT are >3 times the upper limit of normal associated with any ↑ in total bilirubin: Discontinue pegvisomant immediately, perform a comprehensive work-up, including serial liver tests. If liver tests normalize, therapy may be cautiously reinstated with frequent monitoring of liver tests.
  • Do not use serum GH levels to adjust dose. Pegvisomant interferes with the measurement of serum GH concentrations by commercially available assays and may cause an increase in levels.