Abnormal Thyroid Levels in Melanoma: Should You Be Concerned?

In many people with melanoma especially those on immunotherapy abnormal thyroid tests are fairly common and usually manageable. They often reflect inflammation of the thyroid (thyroiditis) that can temporarily cause hyperthyroidism (overactive) and then settle into hypothyroidism (underactive), which is typically treated with daily thyroid hormone. ^{[1] [2]} In some studies, developing thyroid dysfunction during anti–PD‑1 therapy has been linked with better treatment response and longer survival, though this is not always an independent predictor. So while monitoring is important, abnormal thyroid levels are not automatically a bad sign. [PM11] [PM20]

---

Why Thyroid Changes Happen in Melanoma Care

• Immune checkpoint inhibitors (like nivolumab or pembrolizumab) can trigger immune-related thyroiditis. This is one of the most common endocrine side effects of these drugs. ^{[1] [3]}
• Typical pattern: a brief phase of hyperthyroidism from thyroid inflammation, followed by recovery to normal or progression to hypothyroidism requiring replacement therapy. ^{[2] [4]}

---

How Common Is It?

• Thyroid abnormalities occur in a noticeable minority of melanoma patients on immune checkpoint inhibitors, with reported rates ranging from low single digits to over 10–15%, depending on drug and study. ^{[4] [3]}

---

Symptoms to Watch For

• Hypothyroidism (underactive): fatigue, low energy, slow heart rate, weight gain, feeling cold, dry skin, and muscle aches. These symptoms are generally well controlled with levothyroxine (thyroid hormone). ^{[5] [2]}
• Hyperthyroidism (overactive): palpitations, tremor, anxiety, heat intolerance, weight loss; this phase is often transient and managed supportively. ^{[2] [4]}

---

Monitoring and Management

• Regular blood tests (TSH and free T4) are typically checked every 4–6 weeks during immunotherapy and adjusted based on symptoms and levels. Some centers test every cycle early on, then space to every 4–8 weeks after the first few cycles. ^{[6] [6]}
• If hypothyroidism develops, levothyroxine replacement is standard and usually allows treatment to continue. Thyroid recovery can occur, but many people remain on stable replacement without issues. ^[2] [PM7]
• If hyperthyroidism is present, supportive care is used; rare cases of Graves’ disease may need specific therapy and antibody testing. ^{[6] [4]}

---

What Does It Mean for Your Cancer Outcomes?

• Several studies suggest that thyroid dysfunction during anti–PD‑1 therapy correlates with better response and longer overall survival, and clinically significant hypothyroidism requiring treatment has been associated with favorable outcomes. This does not mean thyroid issues cause better outcomes, but they may signal a robust immune effect. [PM11] [PM20]
• Importantly, thyroid adverse events do not appear to worsen overall survival compared with patients without thyroid issues in some cohorts. [PM7]

---

When to Be Concerned

• Seek prompt evaluation if you have severe fatigue, dizziness, fainting, or other signs that could indicate broader endocrine problems (like adrenal insufficiency), as these require urgent care and specific testing. ^{[7] [8]}
• Most thyroid changes are not emergencies and are safely managed with medication and monitoring while cancer treatment continues. ^{[2] [3]}

---

Practical Tips

• Report symptoms early: unusual fatigue, cold intolerance, weight changes, palpitations, or anxiety. Early detection helps tailor therapy. ^{[2] [5]}
• Stay on schedule with labs: consistent TSH and free T4 checks help your team adjust doses promptly. ^{[6] [6]}
• Ask about imaging findings: increased thyroid uptake on PET can be a clue to thyroiditis and has been associated with a higher chance of permanent hypothyroidism in some patients. [PM22]

---

Summary

Abnormal thyroid levels in melanoma especially during immunotherapy are common, typically manageable, and may even be a sign of a favorable immune response. Routine monitoring and timely treatment with thyroid hormone usually keep you feeling well and allow cancer therapy to continue. Stay alert to symptoms, keep your lab schedule, and partner with your oncology and endocrinology teams. ^{[3] [2]} [PM11] [PM20]