Secondary hyperparathyroidism due to Vit D deficiency shows :

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.