Parathormone raises blood Ca⁺⁺ levels by 

(a) promoting bone resorption

(b) promoting reabsorption of calcium in renal tubules

(c) increasing calcium absorption in GI tract

Parathyroid hormone (PTH) increases the Ca²⁺ levels in the blood. 

PTH acts on bones and stimulates the process of bone resorption (dissolution/ demineralisation). 

PTH also stimulates reabsorption of Ca²⁺ by the renal tubules and increases Ca²⁺ absorption from the digested food. 

It is, thus, clear that PTH is a hypercalcemic hormone, i.e., it increases the blood Ca²⁺ levels.