Final answer:
Protein restriction in diets for patients with kidney disease is necessary because it decreases the kidneys' filtration workload, potentially preventing further damage and slowing disease progression.
Step-by-step explanation:
Protein is restricted in the diet for patients with diseased kidneys primarily because protein requires more filtration by the kidneys, which can be strenuous for already compromised renal function. This dietary modification aims to reduce the workload on the kidneys and prevent further damage. When diseased kidneys filter blood, damaged glomerular capillaries allow proteins like albumin to leak into the urine, a condition known as proteinuria. Protein in the urine is a sign of disorders like diabetic nephropathy, indicating that the kidneys' filtration system is not working adequately. Controlling dietary protein intake, along with managing blood sugar levels and hypertension, is crucial to slow down the progression of kidney damage. Unchecked, kidney diseases can lead to a decrease in kidney function and potentially permanent kidney failure, necessitating dialysis, the process of filtering blood with a machine. Therefore, for patients with conditions like nephrotic syndrome, pyelonephritis, and renal failure, limiting protein intake can be part of a therapeutic strategy to conserve remaining kidney function and mitigate symptoms.