Calcium is essential to life and calcium levels need to be tightly regulated in the body within a very narrow range. The calcium-sensing receptor (CaSR) in the parathyroid glands plays a crucial role in this by sensing when levels are low or high and stimulating or suppressing the production of parathyroid hormone (PTH).
Mutations in the CaSR lead to hypocalcaemic disorders such as ADH1, and hypercalcaemic disorders such as FHH1. CaSR mutations cause rare endocrine disorders affecting newborns, children & adults.

‘I remember thinking, ‘Oh it’s only low calcium,’ and we were given tablets and told he would live a normal life on this medication.