The first two talks of this session were by Robert Schrier on hepatorenal syndrome and by Anthony Chang on bile cast nephropathy
Dr. Schrier reviewed the patho-physiology of HRS and reminded us that it’s the renal vasoconstriction that is the end result of cirrhosis. The overfill hypothesis is the current thought (there is increased plasma volume) and increased ascites leading to the elevation in hormones that activate the RAAS.
Some key points:
1. Precipitating factors of HRS: SBP, paracentesis without albumin, GI bleed, alcoholic hepatitis, unknown
2. Hyponatremia is an early surrogate of HRS
3. Criteria for HRS diagnosis criteria (all criteria are required to diagnose HRS)
- Low GFR, indicated by a serum creatinine level higher than 1.5 mg/dL or 24-hour creatinine clearance lower than 40 mL/min
- Absence of shock, ongoing bacterial infection and fluid losses, and current treatment with nephrotoxic medications
- No sustained improvement in renal function (decrease in serum creatinine to <1.5 mg/dL or increase in creatinine clearance to >40 mL/min) after diuretic withdrawal and expansion of plasma volume with 1.5 L of plasma expander
- Proteinuria less than 500 mg/d and no ultrasonographic evidence of obstructive uropathy or intrinsic parenchymal disease
(these are subject to change based on an upcoming guidelines meeting that is going to be published soon)
Dr. Chang then discussed an entity that has been recently been described called bile cast nephropathy.
1. 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. Most of the damage is distal nephron related. The Hall’s stain confirms bilirubin presence. In one series from the speaker’s institution of liver dysfunction patients, 50% of jaundiced patients had intra renal bile casts and 12% of the autopsy cases had extensive involvement of both proximal and distal tubules. 85% of patients with hepatorenal syndrome had bile casts. In the same series, bile casts were seen in 100% of patients with alcoholic cirrhosis. The injury is similar to cast nephropathy seen with myeloma.
2. The level at which they saw more of this entity was a bilirubin of around 26.
3. Many case reports have then been published regarding this entity as well.
Given the above findings, it might be very important to rule out this entity in our cirrhotic patients for two reasons: some might get misdiagnosed as HRS and get inappropriate treatment and secondly, if truly this is an intrinsic renal entity, perhaps these patients do better with a liver-kidney transplant than the liver alone.
I would suggest that the guideline makers of HRS include total bilirubin <20 or 25 be a criteria to diagnose someone with HRS as above 25, perhaps the risk of bile cast nephropathy exists and biopsy might be indicated to confirm.
Post by Dr. Kenar Jhaveri, eAJKD Editor.
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