Pseudohypoparathyroidism in a Chinese girl: A case report

Pseudohypoparathyroidism is a rare genetic disorder characterized by hypocalcemia, hyperphosphatemia, and elevated serum intact parathyroid hormone levels. The taxonomy of pseudohypoparathyroidism is intricate, with heterogeneous clinical presentations and lack of specificity. A school-age Chinese girl was admitted with a 2-day history of fever and a single episode of seizure, with no clinical features of Albright hereditary osteodystrophy. Physical examination revealed positive Chvostek's and Trousseau's signs, with no other significant abnormalities. Laboratory tests revealed hypocalcemia, elevated intact parathyroid hormone levels, and transient hypokalemia (2.8 mmol/L). Whole-exome sequencing showed a 2.1-Kb deletion of exons 4-6 in syntaxin 16 (STX16); however, her parents did not exhibit any such alterations. The patient was finally diagnosed with pseudohypoparathyroidism and administered calcium gluconate perfusion, calcitriol, and elemental calcium. After discharge, her calcitriol and elemental calcium dosages were gradually tapered in the outpatient setting. By the 1-year follow-up, hypocalcemia had been largely corrected; however, her intact parathyroid hormone level remained above the normal reference range. This case of sporadic pseudohypoparathyroidism type Ib with a 2.1-Kb STX16 deletion underscores that pseudohypoparathyroidism can present as fever-induced seizure with transient hypokalemia, highlighting the importance of metabolic and genetic screening in children who experience seizures.