Bile cast nephropathy

Bile cast in renal tubule

Bile casts can sometime be seen in kidneys from autopsy of patients with marked jaundice. The significance of these casts regarding kidney function is not clear. The term cholemic nephrosis had been used in the past to describe functional and histologic abnormalities in the kidneys from jaundiced patients. However, the interest in medical community to study this entity has declined in recent time. Much interest has focused on hepatorenal syndrome which is purely functional in term of pathogenesis.
In order to study prevalence and characteristic of renal bile casts, van Slambrouck et al. looked into 41 autopsy and 3 renal biopsy cases with jaundice. They found that the presence of bile casts correlated with higher serum total and direct bilirubin level. A trend toward higher serum creatinine was noted, but not statistically significant. The amount of bile casts also correlated with the severity of acute tubular injury. Bile casts seems to be associated with poor prognosis, but this may be due to the fact that most of the cases were from autopsy. More study in biopsies is suggested to find out the clinical impact of bile casts in the kidneys.
The authors proposed the term bile cast nephropathy as a subset of patients with cholemic nephrosis or jaundice-related nephropathy. The patients with bile cast nephropathy have a more severe kidney injury. However, the criteria for dianosis was not mentioned in the article.
The mechanism of injury may be due to bilirubin toxicity and obstruction to tubules in similar fashion to myeloma cast nephropathy or rhabdomyolysis.