How should endocrine adverse events be monitored and managed in patients receiving nivolumab?

Monitoring and Management of Nivolumab-Induced Endocrinopathies

Baseline thyroid function (TSH and free T4) must be checked before starting nivolumab, then repeated every 4-6 weeks during treatment, with early morning cortisol and ACTH measured monthly for the first 6 months, then every 3 months for 6 months, then every 6 months for 1 year 1.

Baseline Testing Requirements

Before initiating nivolumab, obtain:

• TSH and free T4 (not TSH alone)
• Early morning (8 AM) cortisol and ACTH
• Glucose and HbA1c
• Consider FSH, LH, and sex hormones (testosterone in men, estradiol in women) if combination therapy with ipilimumab is planned 1

Monitoring Schedule During Treatment

Thyroid Function

• Check TSH and free T4 every 4-6 weeks throughout treatment 2, 1
• Do not rely on TSH alone—in hypophysitis, TSH can remain normal while free T4 is low 2
• Median time to thyroid dysfunction is 14.5 weeks (range 1.5-130 weeks) 2

Adrenal Function

• Early morning (8 AM) cortisol and ACTH:
  • Every month for first 6 months
  • Every 3 months for next 6 months
  • Every 6 months for 1 year thereafter 1
• Critical because adrenal insufficiency can be life-threatening and presents with nonspecific symptoms (fatigue, nausea, hyponatremia) 3, 4, 5

Glucose Monitoring

• Baseline metabolic panel before each cycle to track glycemic trends 1
• If new hyperglycemia develops, check blood or urine ketones immediately (risk of diabetic ketoacidosis) 2

Recognition of Endocrinopathies

Primary Hypothyroidism (Most Common)

• Often follows transient thyrotoxicosis phase 2
• Elevated TSH with low free T4
• Incidence: 9-12% with nivolumab monotherapy 6
• Manage with levothyroxine replacement; nivolumab can continue 7

Hypophysitis/Secondary Adrenal Insufficiency (Most Dangerous)

Red flag presentation: Low or normal TSH with low free T4 suggests central hypothyroidism—immediately evaluate for hypophysitis 2, 1

Key diagnostic features:

• Symptoms: Headache (85%), fatigue (66%), nausea, hyponatremia 1, 3, 4
• Labs: Low free T4 with low/normal TSH, low cortisol with low/normal ACTH
• Timing: Median onset 8-9 weeks with ipilimumab combinations; can occur later with nivolumab monotherapy (after 21 cycles reported) 4
• Imaging: MRI may show pituitary enlargement, stalk thickening, but can be completely normal 1, 4

Critical Management Rule for Hypophysitis

Never start thyroid hormone replacement before cortisol replacement when both deficiencies exist—this can precipitate adrenal crisis by increasing cortisol metabolism 2. Always replace hydrocortisone first.

Management Algorithm

For Suspected Hypophysitis

1. Immediate workup (before steroids if possible):

   • 8 AM cortisol and ACTH
   • TSH and free T4
   • FSH, LH, sex hormones
   • MRI sella with pituitary cuts 1

2. Diagnostic criteria:

   • ≥1 pituitary hormone deficiency (TSH or ACTH required) + MRI abnormality, OR
   • ≥2 pituitary hormone deficiencies 1

3. Treatment:

   • Start hydrocortisone replacement immediately (before thyroid hormone)
   • Most patients require lifelong hormone replacement 2, 1
   • Nivolumab can often continue with appropriate replacement 2

For Primary Hypothyroidism

• Start levothyroxine replacement
• Continue nivolumab 2
• Monitor TSH/free T4 every 4-6 weeks until stable

For Thyroiditis with Thyrotoxicosis

• Usually transient; may progress to hypothyroidism 2, 7
• Symptomatic management (beta-blockers if needed)
• Monitor closely for transition to hypothyroid phase

Common Pitfalls to Avoid

1. Checking TSH alone—will miss central hypothyroidism from hypophysitis 2
2. Assuming normal MRI excludes hypophysitis—diagnosis can be made on biochemical grounds alone 1, 4
3. Starting thyroid replacement before cortisol replacement—can trigger adrenal crisis 2
4. Inadequate screening frequency—current real-world practice shows only 0.5% of patients receive appropriate adrenal screening despite 9% incidence of adrenal insufficiency 5
5. Attributing symptoms to cancer or chemotherapy—fatigue, nausea, and hyponatremia warrant endocrine evaluation 3, 4, 5

Special Considerations

• Combination therapy (nivolumab + ipilimumab): Higher risk of hypophysitis (up to 13%) compared to nivolumab monotherapy 1, 6
• Late-onset events: Endocrinopathies can occur months to years after starting therapy 2, 4
• Patient education: Counsel on symptoms of adrenal insufficiency and need for stress-dose steroids during illness/surgery if on replacement 4
• Hospitalization rates: 35-47% of adrenal insufficiency cases are diagnosed during acute care visits, indicating inadequate outpatient screening 5

The FDA label confirms hypothyroidism/thyroiditis occurs in 12% of patients across indications 6, making systematic monitoring essential rather than optional.