Calicitonin causes hypocalcemia by

Refer KDT 6/e p 330 Calcitonin inhibits bone resorption by direct action on osteoclasts Calcitonin recetpors are present on osteoclasts It also inhibits proximal tubular calcium and and phosphate reabsorption by direct action on kidney However hypocalcemia which occurs overrides the direct action by decreasing the total Ca2+ filtered at the Glomerulus