Here are some of the educational morsels from today:
Serum-to-ascites albumin gradient and ascites total protein
The SAAG (serum albumin value – ascetic fluid albumin value) is more useful than the protein-based exudate/transudate concept. The presence of a gradient ≥ 1.1 g/dL predicts that a patient has portal hypertension with 97% accuracy. This is from the 1992 study by Runyon et al entitled “The serum-ascites albumin gradient is superior to the exudate-transudate concept in the differential diagnosis of ascites” which was published in the Annals of Internal Medicine.
This can be combined with the total protein concentration to help narrow your differential. Rabih + Goop’s pearl from this morning was a high SAAG and high total protein points you towards cardiac etiologies (e.g., right-sided heart failure) of ascites.
The 2×2 table below reviews the differential diagnosis using these two lab values:
|Total ascites protein
< 2.5 g/dL
|Total ascites protein
> 2.5 g/dL
|SAAG ≥ 1.1 g/dL||Portal hypertension due to cirrhosis||Portal hypertension due to hepatic venous outflow obstruction (including right heart failure)|
|SAAG < 1.1 g/dL||Nephrotic syndrome||Malignancy, tuberculosis|
LFT patterns with congestive hepatopathy
We discussed that the typical finding in congestive hepatopathy is elevated bilirubin (usually < 3 mg/dL), which is indirect or unconjugated. However, this can be elevated > 3mg/dL with acute right-sided heart failure and has been used as a predictor of morbidity and mortality in one study.
There is typically a mild increase in AST/ALT and serum alkaline phosphatase is usually normal or only mildly elevated though any/all elevations in LFTs can be seen in congestive hepatopathy and can vary depending on both the severity of the underlying etiology, the time course, and the etiology or underlying liver function.
Etiology of constrictive pericarditis
We reviewed causes of constrictive pericarditis during report. The overwhelming majority of cases are idiopathic (42-61%).
The following percentages are from 6 case series in the cardiology/cardiothoracic literature:
- Post-cardiac surgery (11-37%)
- Post-radiation therapy (2-31%) particularly after Hodgkin disease or breast cancer
- Postinfectious – e.g., tuberculous or purulent pericarditis (3-15%)
- Connective tissue disorder (3-7%)