Cardiac surgery unmasks latent hypoparathyroidism in a child with the 22q11.2 deletion syndrome.

The 22q11.2 deletion syndrome is a developmental field defect of the third and fourth pharyngeal pouches characterized by a spectrum of thymic and parathyroid gland abnormalities and conotruncal cardiac defects. Latent hypoparathyroidism, defined as normocalcaemia at rest but reduced ability to secrete parathyroid hormone (PTH) in response to pharmacologically evoked hypocalcaemia, is found in 30-50% of people with this syndrome. Its natural history is unknown. We describe a 1.5 year-old girl with tetralogy of Fallot, normal calcium metabolism and few facial dysmorphic features who developed transient hypoparathyroidism in the postoperative period, which lasted months and waxed and waned during this observation period. The clinical picture led us to the diagnosis of 22q11.2 deletion syndrome.