Protein casts

Normally in urine, we can detect a very small amount of proteins. These are Tamm-Horsfall proteins, which are made in DCT and are periodically secreted into urine. It is normal to see a very small amount of protein in urine.

A person with nephrotic syndrome will have hyaline casts (protein casts), which will consist of albumin, Tamm-Horsfall proteins, and perhaps other proteins.

One can also have cellular casts:

1. RBC casts, seen in GN (consist of RBCs stuck onto Tamm-Horsfall proteins)

2. WBC casts, seen in pyelonephritis (consist of WBCs stuck onto Tamm-Horsfall proteins). Note: if we have only WBCs, but no casts in urine, this signifies a lower UTI (no kidney involvement if there are no Tamm-Horsfall casts)

These casts end up in the urine and are eventually broken down. This becomes granular casts. Granular casts are non-specific.

Category: Nephrology Notes , Pathology Notes