Sore throat, fever, or mouth ulcers — possible agranulocytosis; hold dose 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 propylthiouracil (ptu)?
Because of liver toxicity risk, it is reserved for the first trimester of pregnancy and thyroid storm rather than first-line maintenance. Its life-threatening adverse effects are agranulocytosis and hepatotoxicity.
Key points to remember
- Inhibits thyroid hormone synthesis and blocks peripheral conversion of T4 to T3, making it useful in thyroid storm.
- Preferred antithyroid drug in the first trimester of pregnancy because methimazole has higher teratogenic risk early on.
- Agranulocytosis (dangerously low white cells) is a serious adverse effect; sore throat and fever are early warning signs.
- Hepatotoxicity, including liver failure, is a boxed-warning risk, more so than with methimazole.
- Therapeutic effect is delayed several weeks because it blocks new hormone production, not stored hormone.
Nursing priorities
- Monitor CBC for agranulocytosis and assess for sore throat, fever, or signs of infection.
- Monitor liver function tests and assess for jaundice, dark urine, or right upper quadrant pain.
- Assess thyroid status (heart rate, weight, temperature, energy) for response and signs of hypothyroidism from overtreatment.
- Administer consistently at the same times each day to maintain stable hormone suppression.
Labs & values
Patient teaching
- Report sore throat, fever, chills, or signs of infection immediately.
- Report yellowing of skin or eyes, dark urine, or upper-right belly pain.
- Take the medication at the same times every day and do not stop abruptly.
- Understand it may take several weeks to feel better as hormone levels fall.
- Avoid foods high in iodine (kelp, seafood) unless directed.
Red flags: report now
- Sore throat, fever, or mouth ulcers — possible agranulocytosis; hold dose and report immediately.
- Jaundice, dark urine, or right upper quadrant pain — possible hepatotoxicity; report now.
- Never give to a nursing or first-trimester patient without confirming it is the intended antithyroid choice.
References
Clinical references for this topic
