This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Pathology
PTH does not cause - 
Select and explain. 
A. Maintains serum Ca2+, B. Ca2+ retention, C. Decreased PO43- excretion, D. May cause osteolysis
C: Decreased PO43- excretion
Answer: C: Decreased PO43- excretion 
Explanation: Effect of parathyroid hormone
On calcium

It increases serum calcium level by


Increases resorption of calcium from bone → This is the most prominent action.
Stimulates reabsorption of Ca by kidney
Stimulates renal activation of it. D which increases intestinal absorption of calcium 

On Phosphorus

Decrease the level of PO43- in Serum by decreasing PO43- reabsorption in the kidney.