The high levels of urea irritate the serous pericardium, making it secrete a thick pericardial fluid that's full of fibrin strands and white blood cells.
Often, the biggest challenge is distinguishing between a transudative and exudative effusion, and the key difference is the amount of protein in the effusion - exudates have much more!
These were not the ravings of imbecility, the sickly effusions of distempered brains; but the exuberance of fancy, that " in a fine phrenzy" wandering, was not continually reminded of its material shackles.