P-116: Pediatric stiff person syndrome with graves’ disease, type 1 diabetes mellitus, and a positive celiac serology

Introduction

Stiff person syndrome (SPS) is a rare autoimmune disorder that presents with painful muscle spasms and progressive muscle stiffening. SPS is associated with serum and CSF antibodies to glutamic acid decarboxylase-65 (GAD-65) with previous reports of developing additional autoimmune disorders.

Objectives

To report a case of SPS that developed Graves’ disease, type 1 diabetes mellitus (T1DM), and a positive celiac serology.

Methods

Retrospective case review.

Results

An 18-month-old girl with a past medical history of congenital first-degree AV block and tricuspid regurgitation presented with an inability to bear weight on her right lower extremity. Nine days later, she presented with an inability to sit up unassisted. An MRI of the brain/spine was unremarkable. A CSF test for autoimmune myelopathy confirmed a diagnosis of SPS with elevated anti-GAD-65 antibodies 4.79 nmol/L (reference range <0.02 nmol/L).

Laboratory investigation showed positive anti-TPO, anti-islet cell, and anti-insulin antibodies. Treatment included diazepam, clonazepam, and monthly IVIG infusions. At 26 months, she developed autoimmune hypothyroidism with TSH of 9.54 uIU/mL (0.35-5.50 uIU/mL), FT4 of 0.64 ng/dL (0.80-1.80 ng/dL), and she started levothyroxine. At 3 years old, she had a TSH of 0.01 uIU/mL, T3 of 306 ng/dL (105-269 ng/dL), FT4 of 2.35 ng/dL, and positive TSI antibodies, confirming Graves’ Disease. Levothyroxine was discontinued and methimazole was initiated. At 5 years old, she developed polyuria, polydipsia, and an HbA1c of 12.0%, confirming T1DM. Recently she had a TTG IgA of 42 U/mL (<15.0 U/mL), concerning for celiac disease. She is awaiting confirmatory endoscopic biopsies and remains on monthly IVIG infusions, oral clonazepam, methimazole, and insulin.

Conclusions

To our knowledge, this is the first case of a pediatric patient with SPS that developed Graves’ Disease, T1DM, and a positive celiac serology. Patients with SPS need close monitoring and counseling for risks of developing autoimmune endocrinopathies.