Sore throat, fever, or signs of infection — possible agranulocytosis; hold and report immediately.
Before you read
Test yourself first: 3 questions
Question 1 of 3
A client on the antithyroid drug propylthiouracil (PTU) should report which sign of a serious adverse effect?
Answer: B. PTU (and methimazole) can cause agranulocytosis — report sore throat, fever, or signs of infection promptly. It can also be hepatotoxic.
Question 2 of 3
A client takes propylthiouracil (PTU) for hyperthyroidism. Which symptom should the nurse teach the client to report immediately?
Answer: A. PTU and methimazole can cause agranulocytosis. The client must report a sore throat, fever, or other signs of infection at once, because these may signal a dangerously low white-cell count. Weight gain, dry skin, and drowsiness are not the priority warning signs for this drug.
Question 3 of 3
A client is prescribed propylthiouracil (PTU) for hyperthyroidism. Which finding should the nurse instruct the client to report immediately?
Answer: B. PTU and methimazole can cause agranulocytosis, a serious drop in white blood cells. The client should immediately report signs of infection such as sore throat, fever, and chills, which may indicate this adverse effect. Mild fatigue, occasional headache, and a slight increase in appetite are not emergencies.
Keep the streak going with more questions like these, each with a full rationale.
What is methimazole?
It works by blocking the synthesis of new thyroid hormone but does not block T4-to-T3 conversion. Like PTU, its serious risks are agranulocytosis and hepatotoxicity, and it is avoided in the first trimester of pregnancy due to teratogenicity.
Key points to remember
- First-line antithyroid drug for nonpregnant hyperthyroid patients; more potent and longer-acting than PTU (often once daily).
- Inhibits new thyroid hormone synthesis but does not block peripheral T4-to-T3 conversion (unlike PTU).
- Avoided in the first trimester of pregnancy because of teratogenic risk (aplasia cutis, fetal anomalies).
- Agranulocytosis is a serious adverse effect; report sore throat and fever promptly.
- Therapeutic effect is delayed several weeks because stored hormone must be depleted first.
Nursing priorities
- Monitor CBC for agranulocytosis and assess for fever, sore throat, or infection.
- Monitor liver function and assess for jaundice or right upper quadrant pain.
- Assess for signs of hypothyroidism (fatigue, weight gain, cold intolerance) indicating overtreatment.
- Administer at the same time daily and teach the importance of adherence.
Labs & values
Patient teaching
- Report any sore throat, fever, or signs of infection right away.
- Report yellow skin or eyes, dark urine, or right-upper belly pain.
- Take once daily at the same time and do not stop without provider direction.
- Expect it to take a few weeks to feel the full effect.
- Notify the provider if pregnancy occurs or is planned.
Red flags: report now
- Sore throat, fever, or signs of infection — possible agranulocytosis; hold and report immediately.
- Jaundice, dark urine, or RUQ pain — possible hepatotoxicity; report now.
- Never give during the first trimester of pregnancy due to teratogenic risk.
References
Clinical references for this topic
