What is the major problem at the cellular level in cystic fibrosis?

A. Stones that are too small to pass typically do not require surgical removal. Smaller stones are usually managed conservatively with hydration and pain management.

B. Mild, intermittent pain for 1 day does not usually indicate the need for surgery. Conservative management is often appropriate for such cases.

C. Obstruction of urine flow is a primary indication for surgical removal of renal stones. If a stone is blocking the urinary tract, it can cause severe pain, infection, or kidney damage, making surgical intervention necessary.

D. A small stone without evidence of size increase may not require surgery unless it is causing symptoms or complications. Most small stones pass naturally over time.

A. The presence of epithelial cells in urinary casts is indicative of acute tubular necrosis (ATN), a condition where the tubular cells in the kidneys are damaged, often due to ischemia or nephrotoxic substances. These damaged cells shed into the urine, forming casts.

B. Glomerulonephritis is characterized by inflammation of the glomeruli and typically leads to hematuria and proteinuria, but it is not specifically associated with epithelial cells in casts.

C. Urinary tract infections (UTIs) usually cause bacteriuria, pyuria, and sometimes hematuria, but not epithelial cell casts.

D. Pyelonephritis is an infection of the kidneys that can cause white blood cell casts and bacteria in the urine, but it is not typically associated with epithelial cell casts.