From the Guidelines
Hyaline casts are primarily caused by conditions that affect kidney function, resulting in increased protein filtration through the glomeruli, and can be associated with various medical conditions, including fever, strenuous exercise, and kidney diseases such as nephrotic syndrome and glomerulonephritis. When evaluating patients with hyaline casts, it is essential to consider the underlying causes, as they can be a sign of an underlying kidney issue. According to the American Urological Association (AUA) and the Society of Urologic Nurses and Associates (SUNA) guidelines, as stated in the study 1, patients with certain features such as proteinuria, dysmorphic RBCs, cellular casts, or renal insufficiency may have medical renal disease, which can cause hematuria, and therefore, should be referred to a nephrologist. Some key points to consider when evaluating hyaline casts include:
- The presence of hyaline casts in the urine can be a normal finding, especially after exercise or dehydration, but persistent or numerous casts may indicate underlying kidney disease.
- Conditions such as congestive heart failure, early acute tubular necrosis, and certain medications like diuretics can also cause hyaline casts to appear in the urine.
- The formation of hyaline casts involves protein precipitation in acidic, concentrated urine with slow flow, creating characteristic tubular molds that are then excreted in urine, as noted in the context of medical renal disease evaluation 1. Given the potential association with kidney disease, it is crucial to investigate further if hyaline casts are persistent or numerous, and to consider referral to a nephrologist if medical renal disease is suspected, while still performing risk-based urologic evaluation.
From the Research
Causes of Hyaline Casts
- Hyaline casts can be detected in patients with normal renal function, and their presence may be associated with increased plasma brain natriuretic peptide (BNP) levels 2
- The presence of hyaline casts in patients without renal dysfunction may suggest underlying cardiovascular conditions 2
- Monoclonal overproduction of kappa and/or lambda light chains can result in renal light chain deposition disease, which may manifest as hyaline tubular casts 3
- Hyaline tubular casts can be composed of protein-protein aggregates, including histones and cathepsin B, in addition to light chains 3
- The formation of light chains and aggregates in hyaline casts may be relevant to the diagnosis and treatment of light chain associated kidney disorders 3
Associated Conditions
- Cardiovascular disease: hyaline casts may be associated with increased plasma BNP levels in patients with cardiovascular disease 2
- Multiple myeloma: hyaline casts may be composed of light chains produced by the malignant clone of plasma cells in patients with multiple myeloma 3
- Monoclonal gammopathy: hyaline casts may be associated with monoclonal gammopathy of renal significance and multiple myeloma 3
- Renal light chain deposition disease: hyaline casts may be a manifestation of this disease, which is characterized by the deposition of light chains in the kidney 3