Calcium homeostasis and disorders of the calcium-sensing receptor

The identification of the CaR has cast light on many aspects of normal extracellular calcium homeostasis, particularly in relation to the regulation of PTH and calcitonin secretion and renal calcium reabsorption. In addition, loss and gain of function CaR mutations have provided an insight into the pathogenesis of the clinical syndromes of FBHH, NSHPT and ADHH. Careful attention to the urinary calcium excretion, together with other investigations, should enable the physician to distinguish these disorders of calcium sensing from other causes of hypercalcaemia and hypocalcaemia.