Final answer:
Post-nephrectomy care should include avoiding strenuous physical activity and paying close attention to diet, specifically by reducing protein, sodium, and nitrogen intake to lessen the burden on the remaining kidney.
Step-by-step explanation:
The nurse will caution the parents of a child who has had a nephrectomy to avoid strenuous physical activity. This is crucial as the remaining kidney needs to adjust to handling the entire body's filtration needs, and strenuous activity could increase the risk of injury to the remaining kidney. Additionally, the parents should also be aware of the need for preventive strategies that include dietary modifications such as a diet low in protein, sodium, and nitrogen intake. Drinking enough water to make 2 to 2.5 liters of urine per day and restricting oxalate-rich foods are also important considerations. These measures help in reducing the excretory load on the kidneys, which is especially important following a nephrectomy.