In conclusion, on the basis of the data from hypercalciuric patients and from MCD4 cells, we provide evidence that, during acute vasopressin action, luminal CaR activation in the collecting duct attenuates AQP2 mediated water reabsorption and urinary concentration in humans, which may reduce the risk of calcium salt precipitation and nephrolithiasis. The gene discussed is CASR; the disease is nephrolithiasis.