In a patient with pyelonephritis (inflammation of the kidney), which type of urinary cast is more likely to be present: fatty, hyaline, muddy brown, red blood cell (RBC), or white blood cell (WBC)?

From the Guidelines

In a patient with pyelonephritis, white blood cell (WBC) casts are the most likely to be present in the urine. This is because pyelonephritis is an infection of the kidney, and WBC casts are a direct indicator of the inflammatory process occurring in the kidney. The presence of WBC casts in urine is a strong indicator of kidney inflammation or infection, which is characteristic of pyelonephritis 1. Some key points to consider when evaluating a patient with pyelonephritis include:

• The patient typically presents with fever, chills, flank pain, nausea, vomiting, or tenderness at the costovertebral angle, with or without symptoms of cystitis 1
• Urinalysis, including assessment of white and red blood cells and nitrite, is recommended for routine diagnosis 1
• A urine culture and antimicrobial susceptibility testing should be performed in all cases of pyelonephritis 1 While other types of casts, such as fatty, hyaline, muddy brown, or red blood cell (RBC) casts, may be present in certain conditions, WBC casts are the most specific to the inflammatory process occurring in pyelonephritis. It's essential to note that the absence of WBC casts does not rule out pyelonephritis, and the diagnosis should be made in conjunction with other clinical findings and tests 1. In clinical practice, the presence of WBC casts in urine can guide the diagnosis and treatment of pyelonephritis, and their absence should not delay the initiation of appropriate antibiotic therapy if clinical suspicion is high.

From the Research

Urinary Casts in Pyelonephritis

In a patient with pyelonephritis, the type of urinary cast that is more likely to be present is:

• White blood cell (WBC) cast, as it is a specific indicator of pyelonephritis 2
• The presence of WBC casts in the urinary sediment is often used to distinguish between cyst infection and acute or chronic pyelonephritis 3
• However, it's worth noting that some patients with pyelonephritis may not have typical urinary tract symptoms or pyuria, and the diagnosis should not be overlooked even if the urine microscopic examination is normal 4

Characteristics of Urinary Casts in Pyelonephritis

Some key characteristics of urinary casts in pyelonephritis include:

• The presence of bacteria in the matrix of the cast, which can be easily demonstrated by routine urinalysis 2
• WBC casts are more likely to be present in patients with pyelonephritis, especially those with acute or chronic pyelonephritis 3
• The absence of WBC casts does not rule out pyelonephritis, especially in patients who have taken antibiotics before visiting the emergency room 4