Pyelonephritis: The Daily PANCE Blueprint

The answer is C. White cell casts

White cell casts in the urine are indicative of inflammation or infection within the renal tubules. In the context of a patient presenting with symptoms such as fever, flank pain, and dysuria, the presence of white cell casts is highly suggestive of acute pyelonephritis. These casts are formed when white blood cells, which are recruited to the site of infection, enter the renal tubules. Their presence in the urine is a key indicator that the urinary tract infection has ascended to the kidneys, causing pyelonephritis.

Explanation for Incorrect Answers:

A. Hyaline casts: Hyaline casts are the most common type of urinary cast and can be seen in normal urine. They are not specifically indicative of infection and are more often associated with concentrated urine or benign conditions.

B. Red cell casts: Red cell casts suggest glomerular disease, such as glomerulonephritis. While they indicate bleeding within the kidneys, they are not typically associated with infection like pyelonephritis.

D. Granular casts: Granular casts can be seen in a variety of renal diseases and are less specific than white cell casts. They can be a sign of tubular damage but are not directly indicative of infection.

E. Fatty casts: Fatty casts are often seen in nephrotic syndrome and are associated with significant proteinuria. They are not indicative of urinary tract infections or pyelonephritis.