Final answer:
Weight gain in a school-age child with primary nephrotic syndrome indicates that the medication prednisone is effective.
Step-by-step explanation:
The nurse will know the medication is effective when the child presents with weight gain.
In primary nephrotic syndrome, the glomerulus is damaged, causing a significant amount of protein to enter the urine. This leads to low serum albumin and high cholesterol. Prednisone, a corticosteroid, is commonly used to treat nephrotic syndrome. One of its side effects is increased appetite and weight gain.
Therefore, when the child undergoing prednisone treatment for primary nephrotic syndrome shows weight gain, the nurse can conclude that the medication is effective.