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.
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.
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