Synonyms:—Waxy kidney; amyloid degeneration.
Definition:—A condition of degeneration of the structure of the kidneys characterized by a deposit of a substance designated as lardacein in the walls of the blood vessels, in the glomeruli, and also in the connective tissue surrounding the tubules.
Etiology:—Amyloid degeneration occurs under circumstances similar to, favorable to, and in connection with development of amyloid degeneration of other organs. This is described as a waxy or lardaceous degeneration, in which lardacein is deposited within the structure of the walls of the capillaries and in the connective tissue of the glomeruli and tubules. It depends upon the prolonged presence of tissue disintegration—necrosis—especially of bony tissue, and suppuration in other organs or tissues at a time when conditions are favorable, both to pus formation and to infection, from the absorption of toxins. Syphilis and tuberculosis, especially of the osseous structures and of the glands, are favorable to its development, and pyemia or em-pyemia are active causes. The condition occurs in connection with chronic malaria, leukemia, or gout, cancer and chronic heart disorder. It also occurs in conjunction with parenchymatous nephritis, but is seldom found with the small, red or granular kidney of interstitial nephritis.
Symptomatology:—The symptoms are not characteristic, and as the condition usually follows a chronic disorder there is apt to be a mistaken diagnosis, or the actual condition is only revealed post mortem. There is usually chronic derangement of the stomach or of the intestinal tract, with slow emaciation and permanent debility. There is anemia and a waxy pallor of the skin, with a shrunken appearance of the countenance—a distinctly cachectic hue. There may be diarrhea, with chronic enlargement of the liver and spleen. Dropsy appears late, if at all, and is usually local and mild in character, involving the feet, ankles and legs below the knee. If heart disorder complicates, the dropsy may be more conspicuous.
The urine presents no pathognomonic phenomena. It may be normal in quantity, or it may vary from the normal only a little in both quantity, color and specific gravity. In advanced cases it is apt to be increased in quantity, with a notable reduction in the specific gravity, resembling that of interstitial nephritis. The urine is passed freely without irritation or pain. The quantity of albumin varies; in rare cases it is absent, but usually there is a trace of albumin. In distinct cases the albumin may be present in considerable quantity. There is a high proportion of globulin present in comparison with the serum-albumin, and this is classed by Salkowski as a diagnostic symptom. There are a few tube casts present; these are of the fatty variety, with some hyaline and granular casts.
Diagnosis:—The diagnosis is often conjectural. It depends upon the relationship of associated conditions as just described. Chronic suppurating diseases, especially necrosis of bone, may be present, with a distinct cachexia, and there may be also chronic enlargement of the liver or spleen, the outlines of which are plainly apparent on palpation. If, during the course of chronic diseases of this character, there should be a rather sudden increase in the quantity of urine, with a corresponding reduction of the specific gravity to 1,007 or 1,005, with a plainly apparent quantity of albumin, usually much more than is found in interstitial nephritis, a diagnosis of this condition is confirmed.
Prognosis:—If an early diagnosis could be made, and the degenerative diseases which occur as causes of this could be influenced by treatment, the prognosis would be favorable. It is too often true that the disease is not discovered until the structural changes are too far advanced to be influenced by the treatment. Under these circumstances the prognosis is always unfavorable.
Treatment:—Measures calculated to prevent destructive tissue change within the body, to promote normal metabolism and improve the oxygen carrying power of the blood, through the restoration of the normal proportion of the red blood corpuscles, is the object to be obtained. This result may be obtained by measures suggested under other wasting diseases. Some readily appropriable salt of iron should be given in conjunction with echinacea or the calcium sulphid, to free the blood from deleterious products. The ethereal tincture of the perchlorid of iron will be available. This, with cod liver oil or the hypophosphites, will be of benefit. The syrup of the iodid of iron will serve an excellent purpose where there is glandular tuberculosis. Under these circumstances phytolacca should be given on general principles with the echinacea. The hygienic and dietary measures suggested in chronic nephritis will be correctly adjustable to this condition and need not be reiterated.