Tamm-Horsfall protein (THP), also known as uromodulin, is the most common protein found in normal human urine.
The kidneys make it exclusively in the thick ascending limb of the loop of Henle.
It forms the main framework of urinary casts and helps protect against kidney infections and stones.
THP traps bacteria like E. coli to stop urinary tract infections.
It helps stop crystals from forming and growing into kidney stones.
Cast Formation: It creates the structural matrix for urinary casts seen during urinalysis.
It helps regulate ion transport and water handling in the nephron.
Clinical Importance
Finding THP-based casts in a urine test is normal in small amounts, but high amounts or specific cast types can signal kidney disease.
Cast Nephropathy: In conditions like multiple myeloma, abnormal proteins bind with THP to form solid casts that block kidney tubules.
Genetic Disorders: Mutations in the gene (UMOD) that builds this protein cause rare inherited kidney diseases leading to high uric acid and kidney failure.