Background: Hypoparathyroidism is usually characterized by hypocalcaemia and a low or inappropriately normal level of parathyroid hormone. Hypoparathyroidism can be due to several underlying pathologies. Anterior neck surgery is the most common cause of acquired hypoparathyroidism, followed by other acquired causes such as autoimmunity, infiltration or radiation. Congenital or familial hypoparathyroidism may be caused by a number of established genetic defects. This case report describes a case of familial hypoparathyroidism with an autosomal dominant pattern of inheritance in a patient who has congenital bone abnormalities and was previously thought to have autoimmune hypoparathyroidism.
Case: A 43 year old female attends clinic for monitoring of hypoparathyroidism. Autoimmune hypoparathyroidism is listed as the cause across several health services over a period of 15 years including 2 pregnancies. At diagnosis corrected calcium was low at 2.02 mmol/L (reference range 2.1-2.6 mmol/L), phosphate elevated at 1.84 mmol/L (reference range 0.8-1.4 mmol/L) and PTH inappropriately low-normal at 1.6 pmol/L (reference range 1.6-6.9 pmol/L). Her medical history includes congenital absence of thumbs bilaterally, left ulnar hemimelia, seronegative rheumatoid arthritis and a pacemaker for tachy-brady syndrome. She is a non-smoker, drinks alcohol rarely and has two biologic children. Her medications are calcitriol 0.25mcg daily, calcium carbonate 1200mg daily, salazopyrin and sotalol, aiming for a serum calcium in the low-normal range. Following a detailed history, the patient revealed her sister has hypoparathyroidism and her deceased father had hypocalcaemia but declined PTH testing. On review of her children’s biochemistry, it was found one had neonatal biochemistry (ionized calcium and PTH) consistent with hypoparathyroidism. The patient was referred to a genetics clinic and genetic testing is being performed.
Conclusion: We report the first case of hypoparathyroidism associated with congenital absence of ulna and thumbs, the underlying cause remains to be elucidated.