Category: Thyroid

PEMBROLIZUMAB INDUCED HYPOTHYROIDISM IN A PATIENT WITH PREVIOUS HISTORY OF GRAVES' DISEASE

Monday, Apr 8
1:00 AM – 2:00 AM

Objective :

Immune related thyroiditis is a well-known adverse effect of checkpoint inhibitors like Pembrolizumab. We present a peculiar case of a patient with a past medical history of Grave’s disease presenting with symptomatic hypothyroidism after treatment with Keytruda (Pembrolizumab). 


 


Methods : N/A


Results : N/A


Discussion :

A 70 year old female with past medical history significant for Type 2 Diabetes Mellitus, Graves' disease and Adenocarcinoma of the lung presented with fatigue, lethargy and constipation. 
The patient was diagnosed with Grave’s disease five years ago and had been on Methimazole. Six months before presentation, her thyroid function tests had normalized and Methimazole was discontinued. Four months before presentation, she had been diagnosed with Stage IV adenocarcinoma of lung and during the workup, she had received one dose of carboplatin / Alimta/ Keytruda. On presentation, her vital signs were stable. Physical examination was unremarkable for any enlargement of the thyroid gland. Thyroid Function Tests showed TSH of 35.37 mIU/L and Free T4 of <0.40 ng/dl . Anti TPO Antibodies were elevated at 3014 IU/ml. She was started on 100 mcg of oral Levothyroxine and was discharged home with close outpatient follow up. Within 2 months of treatment with Levothyroxine, the patient's symptoms of fatigue and constipation improved.


Conclusion : Keytruda ( Pembrolizumab ) is a checkpoint inhibitor which blocks the PD1 receptor (Programmed cell death receptor 1) expressed by activated T cells. It has been approved for treatment of Mestastatic Melanoma and Metastatic Non Small Cell Lung Cancer. Immune related Thyroiditis is a common adverse effect of the anti PD1 monoclonal antibodies like Pembrolizumab. The spectrum of thyroid dysfunction can range from overt hypothyroidism to hyperthyroidism and thyroid storm. Thyroid function tests should be frequently monitored for patients on Anti PD1 Antibodies. This case demonstrates that a patient with previous history of Grave’s disease could develop hypothyroidism after being started on Anti PD1 Antibody. The presence of Anti TPO antibodies suggests an autoimmune basis.
With the increasing use of checkpoint inhibitors for treatment of cancer, endocrinologists should be well aware of the potential adverse effects of these drugs and further guidelines should incorporate management of these conditions.

Puneet Dhillon

Resident
Abington Jefferson Health
Willow Grove, Pennsylvania

I'm a second year Internal Medicine Resident at Abington Jefferson Health. I have always been fascinated by Endocrinology.

Harshwant Grover

Resident
Abington Jefferson Health
Willow Grove, Pennsylvania

Second Year Internal Medicine Resident.

Jaspreet Virdi

Attending Physician
Abington Memorial Hospital
Abington, Pennsylvania

Attending Physician