Given the following data from a patient - urine output 1.5 L/day; plasma creatinine 1.0 mg/dL; urinary creatinine 1.2 mg/mL; plasma phosphate 0.002 mEq/mL; urinary phosphate 0.05 mEq/mL - what can you reliably conclude about the renal handling of phosphate?
A) There is net secretion of phosphate.
B) There is net reabsorption of phosphate.
C) Phosphate is neither secreted nor reabsorbed.
D) Phosphate is fractionally filtered.
E) The extraction ratio of phosphate is greater than 1.

Question

Quizplus · Accepted Answer

The renal handling of phosphate primarily involves its reabsorption from the filtrate back into the bloodstream. Given the data, with a higher concentration of phosphate in the urine compared to plasma, it indicates that although phosphate is filtered, a significant portion is reabsorbed, as the body typically conserves phosphate due to its importance in various physiological processes. The fact that there is still phosphate present in the urine does not indicate net secretion or that it is neither secreted nor reabsorbed; rather, it shows that while phosphate is filtered, the majority is reabsorbed, which is a characteristic behavior of renal phosphate handling.

Given the Following Data from a Patient - Urine Output