Unusual Endocrinopathies in 18q Deletion Syndrome: Pseudoparathyroidism and Hyper-/Hypo-Thyroidism

Anne Marie D Kaulfers; Whei Ying Lim; Samar K Bhowmick

doi:10.1016/j.aace.2020.12.012

Unusual Endocrinopathies in 18q Deletion Syndrome: Pseudoparathyroidism and Hyper-/Hypo-Thyroidism

AACE Clin Case Rep. 2020 Dec 24;7(3):192-194. doi: 10.1016/j.aace.2020.12.012. eCollection 2021 May-Jun.

Authors

Anne Marie D Kaulfers¹, Whei Ying Lim¹, Samar K Bhowmick¹

Affiliation

¹ Department of Pediatric Endocrinology, University of South Alabama, Mobile, Alabama.

Abstract

Objective: To describe new and unusual endocrinopathies in children with de novo 18q deletion (18q-) syndrome.

Methods: We describe 2 patients who have atypical thyroid conditions and 1 who also developed symptomatic hypocalcemia.

Results: The first patient developed hyperthyroidism at the age of 3 years, with a free thyroxine level of 3.9 (range, 0.8-1.8) ng/dL. Thyroid peroxidase antibodies were 262 (range, 0-32) IU/mL, and thyroid-stimulating immunoglobulin antibodies were 384% (range, 0-139%). On low-dose methimazole treatment, she developed hypothyroidism. Thyroid-stimulating hormone (TSH) level was 163 (range, 0.4-4.5) mIU/mL. Moreover, she later developed growth hormone deficiency. The second patient developed hypothyroidism at the age of 4 years, with a TSH level of 46 mIU/mL. However, TSH remained elevated at levels of 10 to 24 mIU/mL for 3 years, despite appropriate treatment, suggesting TSH resistance. She then developed hypocalcemic seizures and was diagnosed with pseudohypoparathyroidism. Her total calcium level was 6.6 (range, 8.5-10.5) mg/dL and parathyroid hormone level was 432 (range, 15-65) pg/dL.

Conclusion: The first patient had a mixed picture of autoimmune hypothyroidism and hyperthyroidism, requiring a combination of methimazole and levothyroxine to achieve a euthyroid state. For the second patient, the mild TSH resistance was possibly the early suggestion of a parathyroid hormone resistant state. Although growth hormone deficiency and hypothyroidism are common in patients with 18q- syndrome, the occurrence of hyperthyroidism due to Graves' disease with the coexistence of Hashimoto's hypothyroidism is rare. Pseudohypoparathyroidism has not yet been reported in patients with 18q- syndrome.

Keywords: 18q-, 18q deletion; MTZ, methimazole; PHP, pseudohypoparathyroidism; PTH, parathyroid hormone; TPO, thyroid peroxidase; TSH, thyroid-stimulating hormone; TSI, thyroid-stimulating immunoglobulin; genetics; growth disorder; parathyroid diseases; pediatrics; thyroid diseases.

Publication types

Case Reports