irAEEndocrine emergencyICD-10 E23.0
ICI-related hypophysitis
Immune-checkpoint inhibitor hypophysitis · ipilimumab hypophysitis · pituitary irAE
ICI-related hypophysitis is a less common but potentially life-threatening endocrine irAE most strongly associated with anti-CTLA-4 (ipilimumab, 10-17% incidence) and combination ICI. It causes pan-hypopituitarism with secondary adrenal insufficiency as the urgent / dangerous component requiring immediate hydrocortisone replacement. Unlike thyroid irAE, hormonal replacement is often permanent. ESMO immune-toxicity guidance and Society for Endocrinology emergency guidance support urgent same-day endocrinology input when adrenal insufficiency is suspected.
CurrentLast reviewed 16 May 2026
Epidemiology
- Incidence:
- Anti-CTLA-4 monotherapy (ipilimumab): 10-17%.
- Combination ICI (ipilimumab + nivolumab): comparable to or higher than ipilimumab monotherapy (commonly ~7-13% with dose-attenuated regimens; higher with ipilimumab 3 mg/kg).
- Anti-PD-1 monotherapy: <1%.
- Onset: typically 8-12 weeks (range 4-72 weeks).
- Male predominance.
- Pituitary enlargement on MRI in >75% (cf "lymphocytic hypophysitis" without ICI).
Clinical features
- Headache — commonly the first symptom.
- Visual disturbance: blurred vision, diplopia, visual-field defect (rare).
- Fatigue, weakness.
- Nausea, vomiting, anorexia.
- Hypotension, especially postural.
- Hyponatraemia.
- Sexual dysfunction: amenorrhoea, erectile dysfunction, loss of libido.
- Cold intolerance, constipation (central hypothyroidism).
- Adrenal crisis:
- Severe hypotension, shock.
- Hypoglycaemia.
- Hyponatraemia, hyperkalaemia uncommon (vs primary adrenal insufficiency).
- Life-threatening; immediate IV hydrocortisone required.
Pituitary axis affected
| Axis affected | Hormones | Clinical effect |
|---|---|---|
| ACTH (most common, ~80%) | Low ACTH → low cortisol | Secondary adrenal insufficiency; emergency. |
| TSH (~50-70%) | Low TSH → low T4 | Central hypothyroidism. |
| FSH / LH (~50-70%) | Low FSH / LH → low oestrogen / testosterone | Central hypogonadism. |
| GH (~50%) | Low GH → low IGF-1 | Less impact in adults. |
| Prolactin | Variable (often low; raised in some) | Galactorrhoea (rare). |
| ADH | Posterior pituitary rarely affected | Diabetes insipidus (rare). |
Workup
- Bloods:
- Cortisol (9am preferred); ACTH; sodium; potassium; glucose.
- TSH, free T4 (free T4 may be low with normal / low TSH in central hypothyroidism).
- FSH, LH, oestradiol / testosterone.
- Prolactin.
- IGF-1.
- U&E, glucose.
- Short Synacthen test — to confirm adrenal insufficiency.
- Pituitary MRI with contrast: enlarged gland with homogeneous enhancement; stalk thickening; later atrophy.
- Visual field testing if MRI shows chiasmal compression.
- Same-day endocrinology consultation for any suspected case.
Management
- Adrenal crisis suspicion / confirmed (emergency):
- IV hydrocortisone 100 mg stat; then 50 mg QDS.
- Fluid resuscitation (saline; glucose if hypoglycaemic).
- Admit; monitor closely.
- Transition to oral hydrocortisone 10 mg morning + 5 mg afternoon + 5 mg evening (or per local protocol) once stable.
- Central hypothyroidism:
- Levothyroxine 1.6 µg/kg/day.
- Always replace cortisol first before T4 to avoid precipitating adrenal crisis.
- Monitor by free T4 (not TSH — unreliable in central hypothyroidism).
- Hypogonadism:
- Sex hormone replacement per endocrinology / sexual-health input; not always lifelong.
- Counsel re fertility, bone health, libido.
- High-dose steroids for irAE itself: prednisolone 1-2 mg/kg/day for symptomatic mass effect (headache, visual disturbance) — short course; tapered over weeks.
- NO benefit of high-dose steroids on long-term pituitary recovery — replacement therapy mainstay.
- Hold ICI for symptomatic / G3 disease; restart usually possible once hormone replacement stable.
- Long-term follow-up:
- Lifelong endocrinology follow-up.
- Steroid emergency card.
- Sick-day rules (double / triple hydrocortisone dose during illness).
- Annual / biannual review of all axes — some recovery may occur (esp. thyroid; rarely adrenal).
References
- Haanen J et al. ESMO Clinical Practice Guideline for immune-related adverse events. Ann Oncol. 2022;33:1217-1238.
- Faje A et al. Hypophysitis secondary to nivolumab and pembrolizumab is a clinical entity distinct from ipilimumab-associated hypophysitis. Eur J Endocrinol. 2019;181:211-219.
- Min L et al. Systemic high-dose corticosteroid treatment does not improve the outcome of ipilimumab-related hypophysitis. Endocr Pract. 2015;21:1057-1064.
- Percik R, Criseno S, Adam S, Young K, Morganstein DL. Diagnostic criteria and proposed management of immune-related endocrinopathies following immune checkpoint inhibitor therapy for cancer. Endocr Connect. 2023;12(5):e220513.
- Higham CE, Olsson-Brown A, Carroll P, Cooksley T, Larkin J, Lorigan P, Morganstein D, Trainer PJ; Society for Endocrinology Clinical Committee. Endocrine emergency guidance: acute management of the endocrine complications of checkpoint inhibitor therapy. Endocr Connect. 2018;7(7):G1-G7.
- Schneider BJ et al. ASCO clinical practice guideline update: management of immune-related adverse events. J Clin Oncol. 2021;39:4073-4126.
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