This would actually increase serum phosphate levels. However, the patient's PTH is low, which would lead to decreased phosphate reabsorption and hence increased phosphate excretion.

This response would typically be seen with high, not low, PTH levels.

PTH plays a significant role in regulating phosphate reabsorption. With decreased PTH levels, there would be a change in phosphate reabsorption, specifically a decrease.

Parathyroid hormone (PTH) inhibits phosphate reabsorption in the proximal tubule leading to phosphate excretion. Therefore, low PTH levels as seen in this patient would lead to decreased phosphate reabsorption, and hence increased phosphate excretion in the urine via the distal tubules.