Although we did not observe frank hypercalciuria or hypermagnesiuria on any of the time points in iKsp‐Pkd1−/− mice, the similar urinary Mg2+ and Ca2+ excretion as control animals implies a renal leak, that is, the inability of the kidneys to increase reabsorption upon reduced serum levels. The gene discussed is PKD1; the disease is Hypercalciuria.