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: Physiology
Secondary hyperparathyroidism due to Vit D deficiency shows : 
Select and explain. 
A. Hypocalcemia, B. Hypercalcemia, C. Hypophosphatemia, D. Hyperphosphatemia
C: Hypophosphatemia
Answer: C: Hypophosphatemia 
Explanation: C i.e. Hypophosphatemia PTH increases phosphate excretion in urineQ. This phosphaturic action is due to decreased reapsorption of phosphate in distal tubules. Secondary Hyperparathyroidism d/t -Vit D deficiency - This results from decreased serum Ca2+. - The released parathyroid hormone directs its activity to increase serum Ca2+ at the cost of of loss of phosphate from the body - hypophosphatemiaQ. - PTH mobilizes both Ca2+ & phosphate from the bone to increased level of both in blood initially, while it reabsorbs the filtered Ca2+ from renal tubules, it fails to reabsorb phosphate which is lost in urine.