Immune Checkpoint Inhibitors (ICI): Endocrine related side effects

Immune checkpoint inhibitors (ICIs) are a type of treatment used to help our immune system identify and destroy cancer cells. Because of the way that Immune Checkpoint Inhibitors (ICIs) work, they can result in unique side effects called immune-related adverse events (IrAEs). Immune related side effects result from the immune system attacking cells that are not cancer. IrAEs can often resemble autoimmune disorders and can affect any organ in the body. 

What is the endocrine system? 

The endocrine system is a set of organs that helps control the hormones in your body. These hormones are a vital part in regulating many important functions such as metabolism, reproduction, mood, and more. Although endocrine disorders can be an uncommon side effect of immune checkpoint inhibitors, it is still important to be aware of the symptoms so that you can communicate this with your provider.

Below is a table of potential endocrine conditions and their corresponding symptoms.  

Immune related condition 

Area effected  

Symptoms 

Tests to diagnose 

Hypothyroidism (Low thyroid hormone levels)  

Thyroid 

Fatigue 

Weight gain 

Slowed heart rate 

Trouble tolerating cold 

Joint/Muscle pain 

Depression 

Thyroid Stimulating Hormone (TSH) 

Thyroxine (T4)  

Hyperthyroidism (High thyroid hormone levels)  

Thyroid 

Warmth and/or sweating 

Anxiety 

Weight loss 

Tremors 

Increased heart rate or palpitations 

Increased bowel movement frequency 

Shortness of breath 

Goiter 

Thyroid Stimulating Hormone (TSH) 

Thyroxine (T4) 

Hypophysitis 

(Inflammation of the pituitary gland) 

Pituitary Gland 

Fatigue 

Headache  

Cold intolerance 

Excessive thirst 

Excessive urination 

Weight loss 

Electrolyte imbalance 

 

Adrenocorticotropic Hormone (ACTH) 

Thyroid Stimulating Hormone (TSH) 

Follicle Stimulating Hormone (FSH) 

Luteinizing hormone (LH) 

Growth Hormone (GH) 

Prolactin 

Brain MRI (to identify swelling of pituitary gland)  

Adrenal Insufficiency

or

Adrenal Crisis (This is a medical emergency) 

Adrenal Gland 

Dehydration 

Nausea/Vomiting 

Fatigue 

Confusion 

Weakness 

Abdominal pain 

Low blood pressure 

Weight loss 

Complete Metabolic Panel (CMP) 

Serum Cortisol Corticotropin (ACTH)

Aldosterone 

Renin  

Type 1 Diabetes 

Pancreas 

Excessive thirst 

Frequent urination 

Weight loss 

Confusion 

Lethargy 

Rapid breathing 

Nausea/Vomiting 

Abdominal pain 

Blood sugar levels 

Urine tests to check for sugar and protein  

Labs to check electrolytes and kidney function   

How are these side effects managed? 

Treatment of endocrine disorders, such as those described above, can vary depending on the severity of your symptoms and lab results. Potential management options include: 

  • Replacement of the hormone that is low (such as thyroid hormone, insulin, or mineralocorticoids) 

  • Referral to an endocrinologist (a physician who specializes in the endocrine system) to help diagnose and manage these side effects 

  • Delays in treatment  

  • Discontinuation of current treatment regimen   

Always communicate any new or changing symptoms with your provider. If you are seeing a provider outside of your usual care team, be sure to tell them that you are on immunotherapy. It may also be a good idea to keep a list of your current treatment, as well as your oncologist’s name, and contact information either in your wallet or on your phone.