Discussion via pics: Bile Cast Nephropathy

 

Image made via biorender.com
Images in that obtained from:

https://www.kidney-international.org/article/S0085-2538(15)55928-0/fulltext
https://rrtjournal.biomedcentral.com/articles/10.1186/s41100-020-00265-https://laboratoryinfo.com/types-of-crystals-in-urine/

Consult Rounds: Cholemic nephrosis or Bile cast nephrpathy or should we say Jaundice associated nephropathy

Bile cast nephropathy or also called cholemic nephrosis represents a spectrum of renal injury from proximal tubulopathy to intrarenal bile cast formation found in patients with severe liver dysfunction. Bile can be toxic directly to the tubule or can form casts and have similar damage as myeloma cast nephropathy.

Recently this entity has gained some interest in the literature.

1.      Classically seen with patients with acute or chronic liver disease

2.      Usually, the total bilirubins are over 20 and conjugated over 16 is the cases that had bilirubin casts on kidney biopsies

3.      The LFTS were also higher in these patients

4.      The cause of liver disease doesn’t matter

The mechanisms responsible for tubular dysfunction include uncoupling of mitochondrial phosphorylation (thereby decreasing ATPase activity) by bilirubin  and oxidative damage of tubular cell membranes as well as inhibition of Na-H and Na-K pumps in the tubular cell membranes by bile acids. Cholemic nephrosis is reversible provided bilirubin levels are reduced early. This recovery is however delayed if there is extensive bile cast formation.

Some have suggested jaundice-related nephropathy as a replacement for cholemic nephrosis. Based on their definition, jaundice-related nephropathy would encompass the spectrum of injury that ranges from proximal tubulopathy to extensive tubular injury and tubular pigment. 

As bile passes via tubules, there is pigment nephropathy.

Pathology findings include: extensive acute tubular injury with bile stained tubular casts.
Macroscopic findings will include bile stained yellowish discoloration of the kidneys in jaundiced patients which become dark green after formalin fixation.
The Hall's stain confirms bilirubin presence.

Other interesting articles on this topic

http://www.kidney-international.org/article/S0085-2538(15)56212-1/fulltext

http://onlinelibrary.wiley.com/doi/10.1111/hdi.12169/pdf

http://www.ajkd.org/article/S0272-6386(16)30488-7/abstract

https://www.karger.com/Article/Pdf/371689

Clinical Case 73: Answers and Summary

Which of the following statements are true regarding bile cast nephropathy?

It is also called cholemic nephrosis

  10 (41%)

 

It is no different than hepatorenal syndrome

  2 (8%)

 

The casts that form in the kidney are correlated with higher total and direct bili levels

  12 (50%)

 

Mechanism of the casts is similar to myeloma casts or myoglobin casts

  5 (20%)

 

It is also called jaundice associated nephrosis

  4 (16%)

 

No such entity exists

  4 (16%)

 

Bile cast nephropathy has been described in older literature as cholemic nephrosis or jaudice associated nephrosis. In the most latest publication in KI 2013, this entity takes a new leap and re introduction to the nephrology world. This entity represents a spectrum of disease from proximal tubulopathy to intrarenal bile cast formation found in patients with severe liver dysfunction. The researchers looked at 44 cases and found that 24 patients had bile casts with involvement of distal nephron segments in 18 mild cases and extension to proximal tubules for 6 severe cases. Eleven of 13 patients with hepatorenal syndrome(HRS) and all 10 with alcoholic cirrhosis had tubular bile casts. These casts significantly correlated with higher serum total and direct bilirubin levels, and a trend toward higher serum creatinine, AST, and ALT levels. Bile casts may contribute to the kidney injury of severely jaundiced patients by direct bile and bilirubin toxicity, and tubular obstruction. The mechanisms are analogous to the injury by myeloma or myoglobin casts. It is different from HRS as in HRS, the injury is more pre renal and kidney biopsy is usually normal.