Endocrine Abstracts

Background: Genetic causes of hypocalcaemia can be overlooked in patients presenting without apparent syndromic features. One such example is DiGeorge syndrome, which is often diagnosed in childhood but rarely in adulthood.

Case presentation: A 21-year-old lady was referred to our endocrinology clinic regarding chronic hypocalcaemia (adjusted calcium 1.98 mmol/l). This was first diagnosed at the age of eight with no clear cause identified. Her past medical history included hypoparathyroidism treated with Adcal D3 and infertility. Besides a short stature, the rest of examination was normal. Initial workup showed low parathyroid hormone (0.6 pmol/l, reference range 1.6-6.9 pmol/l) with normal levels of magnesium, phosphate, alkaline phosphatase, renal and liver function tests. Urinary calcium: creatinine ratio was raised at 0.36 (reference <0.2) and 25-hydroxyvitamin D was 33 nmol/l suggesting insufficiency. Investigations for infertility (pituitary profile and androgens) were normal except suppressed gonadotrohins with raised oestradiol levels and pregnancy was later confirmed on a urinary pregnancy test and a 12-week gestational scan. Unfortunately, 20-23 weeks’ scans demonstrated a congenital heart disease and the couple chose termination of pregnancy declining antenatal cytogenetics. The foetus was noted to have mild hypertelorism, micrognathia, arachnodactyly, hypoplastic thymus, large ventricular septal defect and type 1 truncus arteriosus. Karyotype was normal (46XX) but chromosomal microarray analysis revealed a 22q11.2 microdeletion. Similarly, the mother’s karyotype was normal (46XX) but the same 22q11.2 microdeletion was found and DiGeorge syndrome was diagnosed. The father had normal genetic tests. Subsequent thorough examination of our patient revealed subtle hypertelorism and arachnodactyly with a normal echocardiogram. In following years, she birthed two healthy babies without the 22q11.2 microdeletion. Her calcium levels have been stable on 1-alfacalcidol and Adcal D3.

Conclusions: This rare case reminds clinicians to follow a systematic approach when evaluating hypocalcaemia and consider the possibility of a late diagnosis of congenital hypoparathyroidism even in adulthood.