Unusual Endocrinopathies in 18qdeletion syndrome: Pseudohypoparathyroidism and Hyper-/Hypo-thyroidism

ABSTRACT Objective The objective of this report is to describe new and unusual endocrinopathies in children with de novo 18q deletion (18q-) syndrome. Methods We describe two patients who have atypical thyroid conditions and one who also developed symptomatic hypocalcemia. Results The first patient developed hyperthyroidism at age 3 years old, with free thyroxine level of 3.9 ng/dl (range 0.8-1.8). Thyroid Peroxidase antibodies were 262 IU/ml (range 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.