Final answer:
Checking the child's urine for protein is crucial in monitoring treatment efficacy and identifying complications in nephrotic syndrome, where damaged glomeruli cause protein leakage into urine.
Step-by-step explanation:
The reason why it is necessary to check the child's urine for protein is to monitor the effectiveness of the treatment and to identify any potential complications related to nephrotic syndrome. In nephrotic syndrome, the glomeruli are damaged, allowing a significant amount of protein, which should normally be retained in the blood, to leak into the urine, resulting in proteinuria. By regularly testing for protein in the urine, health care providers can track the patient's response to therapy and make adjustments as needed, aiming to reduce the protein levels in the urine and manage the condition effectively. It also helps in screening for the progression of kidney damage and evaluating the need for further treatment adjustments.