Endocrine Abstracts

A 32-year-old male of Lithuanian background presented to ED after a tonic-clonic seizure at work. There were no obvious precipitating factors, though he had started night shifts 6 months prior. Examination was significant for severe dental hypoplasia and abnormal facies. Biochemistry showed primary hypoparathyroidism: adjusted calcium mmol/L 1.47 (low), phosphate 1.30 mmol/L (high), magnesium 0.84 mmol/l, fT4 16.2 pmol/l, TSH 5.66 mU/L (high), PTH 1.4 pmol/l (low), vitamin D 22 nmol/L(low) Intracranial imaging showed grade I Chiari malformation (not felt to have contributed to seizures) Further history revealed recurrent childhood infections requiring hospitalisation, but no previous diagnosis of hypocalcaemia. He reported intermittent leg cramping in the weeks before presentation, but no paraesthesia. He was treated with IV calcium gluconate followed by oral calcium carbonate, high-dose cholecalciferol and alfacalcidol Bloods were sent for chromosomal analysis which revealed breakpoints within 22q11.2, with heterozygous deletion of approximately 2.2Mb of the DiGeorge/Velo-Cardio-Facial Syndrome Critical Region.

Learning points: 1. Patients with hypocalcaemia and dysmorphic features should have a chromosomal microarray analysis requested rather than the R153 hypoparathyroid gene panel, which only screens for single gene mutations; otherwise this diagnosis would have been missed.

2. This is a rare late presentation of DiGeorge’ syndrome, most affected individuals will either develop hypocalcaemia during the neonatal period or be diagnosed during childhood due to developmental delay; late presentation of hypocalcaemia is unusual due to presumed compensatory hyperplasia of existing parathyroid tissue. Hypocalcaemia can be precipitated in adults during periods of stress.

3. The estimated prevalence of DiGeorge is 1/3000 – 1/6000 live births, but the number may be higher due to the condition’s variability, and lack of neonatal screening.

4. The diagnosis should be made due to the necessity of screening for other syndromic sequalae which will be discussed.