Hyaline casts are cylindrical and clear, with a low refractive index, so they can easily be missed on cursory review under brightfield microscopy, or in an aged sample where dissolution has occurred whereas, on the other hand, phase contrast microscopy leads to easier identification. Given the ubiquitous presence of Tamm–Horsfall protein, other cast types are formed via the inclusion or adhesion of other elements to the hyaline base. Granular casts
The second-most common type of cast, granular casts can result either from the breakdown of cellular casts or the inclusion of aggregates of plasma proteins (e.g., albumin) or immunoglobulin light chains. Depending on the size of inclusions, they can be classified as fine or coarse, though the distinction has no diagnostic significance. Their appearance is generally more cigar-shaped and of a higher refractive index than hyaline casts. While most often indicative of chronic renal disease, these casts, as with hyaline casts, can also be seen for a short time following strenuous exercise. The "muddy brown cast" seen in acute tubular necrosis is a type of granular cast. Waxy casts
Thought to represent the end product of cast evolution, waxy casts suggest the very low urine flow associated with severe, longstanding kidney disease such as kidney failure. Additionally, due to urine stasis and their formation in diseased, dilated ducts, these casts are significantly larger than hyaline casts. They are cylindrical. They possess a higher refractive index.
They are more rigid, demonstrating sharp edges, fractures, and broken-off ends.Waxy casts are broad casts, which is a more general term to describe the wider cast product of a dilated duct. It is seen in chronic kidney failure. In nephrotic syndrome many additional types of cast exist including broad and waxy casts if the condition is chronic (this is referred to as a telescopic urine with the presence of many casts). Fatty casts
Formed by the breakdown of lipid-rich epithelial cells, these are hyaline casts with fat globule inclusions, yellowish-tan in color. If cholesterol or cholesterol esters are present, they are associated with the "Maltese cross" sign under polarized light. They are pathognomonic for high urinary protein nephrotic syndrome. Pigment casts
Formed by the adhesion of metabolic breakdown products or drug pigments, these casts are so named due to their discoloration. Pigments include those produced endogenously, such as hemoglobin in hemolytic anemia, myoglobin in rhabdomyolysis, and bilirubin in liver disease. Drug pigments, such as phenazopyridine, may also cause cast discoloration. Crystal casts
Though crystallized urinary solutes, such as oxalates, urates, or sulfonamides, may become enmeshed within a ketanaline cast during its formation, the clinical significance of this occurrence is not felt to be great. Cellular casts
Red blood cell casts
The presence of red blood cells within the cast is always pathological and is strongly indicative of granulomatosis with polyangiitis, systemic lupus erythematosus, post-streptococcal glomerulonephritis, or Goodpastures syndrome. They can also be associated with renal infarction and subacute bacterial endocarditis.