title: Delayed-onset hypoparathyroidism in an adolescent with chromosome 22Q11 deletion syndrome.
abstract: OBJECTIVE
  To describe the first case of established chromosome 22q11 deletion syndrome with late onset presentation of hypocalcemia secondary to hypoparathyroidism.
  
  
  METHODS
  We present the history, clinical and laboratory investigations, and management of a 17-year-old adolescent boy who presented with 3 separate seizures secondary to hypocalcemia. This patient had an established diagnosis of chromosome 22q11 deletion syndrome at the time of the seizure presentations, but had previously normal calcium levels.
  
  
  RESULTS
  Hypocalcemia was noted during each seizure, with corrected calcium levels ranging from 6.64 to 7.76 mg/dL (reference range, 8.52 to 10.52 mg/dL). The hypocalcemia was secondary to hypoparathyroidism, with parathyroid hormone levels < 2.75 pg/mL (reference range, 22.9 to 68.75 pg/mL). He was treated with calcitriol, 0.5 μg daily, and calcium carbonate, 2,400 mg daily, leading to normalization of serum calcium and resolution of seizures.
  
  
  CONCLUSIONS
  Chromosome 22q11 deletion syndrome is a relatively common genetic disorder with a wide variety of phenotypic manifestations including cardiac abnormalities, abnormal facies, thymic dysfunction, cleft palate, and hypocalcemia. This case shows that medical practitioners should be aware that hypocalcemia can present after an established diagnosis, which has implications for the management of this disorder.
authors.affiliation: Department of Endocrinology, University of Sydney Nepean Clinical School, Penrith, NSW, Australia. jkam7752@uni.sydney.edu.au
authors.forename: Jaspreet S
authors.initials: JS
authors.lastname: Kambo
authors.forename: Christian M
authors.initials: CM
authors.lastname: Girgis
authors.forename: Bernard L
authors.initials: BL
authors.lastname: Champion
authors.forename: Jack R
authors.initials: JR
authors.lastname: Wall
mesh_terms: D058165:22q11 Deletion Syndrome / Q000175:diagnosis* / Q000235:genetics / Q000378:metabolism; D000293:Adolescent; D006801:Humans; D007011:Hypoparathyroidism / Q000175:diagnosis* / Q000235:genetics / Q000378:metabolism; D008297:Male; D012640:Seizures / Q000175:diagnosis / Q000235:genetics / Q000378:metabolism