Urology: Keeping the Filters Working

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Immune Reaction. One of the common types of kidney disease, said Cornell's Dr. David D. Thompson, is inflammation of the filtering system itself, called glomerulonephritis. Richard Bright, who died before Pasteur even suggested the microbial theory of infectious diseases, noted that many victims of this kidney disorder had recently recovered from scarlet fever. Now that scarlet fever is known to be caused by streptococci, said Dr. Thompson, physicians can predict an outbreak of nephritis after a scarlet-fever epidemic.

Just how the streptococci cause the kidney inflammation, however, is not yet known. It is not by direct infection. Likeliest explanation, said Dr. Thompson, is an immune reaction. The inflamed kidneys take weeks or months to return to normal. Children are more likely than adults to develop nephritis. But 90% of children, as against only 50% of adults, recover completely.

Perhaps the most common of all kidney infections, especially in women and children, is pyelitis—inflammation of the collecting basin in the middle of the kidney, where urine accumulates before it passes to the bladder. Since the inflammation usually involves other parts of the kidney as well, it is given the more inclusive name of pyelonephritis.

Any of several bacteria can cause pyelonephritis, but the worst offender is the colon bacillus. In women, infection is often precipitated by pregnancy; in men, by a kidney stone or prostate trouble. In many cases, pyelonephritis persists over many years. As the kidneys eventually lose their filtering efficiency, the patient may die of uremic poisoning.

Among the common forms of kidney disease that are not caused by inflammation is one that used to be called nephrosis, but is now labeled the nephrotic syndrome. Its origins are unknown, said Cornell's Dr. E. Lovell Becker, though sometimes it clearly follows an earlier kidney disease, or it is the result of an entirely different disease, such as diabetes. Even its course is impossible to predict. "The only thing certain," said Dr. Becker, "is that a fair number of these patients will go on to recover."

Any form of longstanding kidney disease results in the progressive destruction of nephrons, until there are too few left to filter the blood adequately. This is the stage traditionally known as Bright's disease, in which pyelonephritis may be indistinguishable from glomerulonephritis. Kidney diseases are so interrelated, Dr. Luckey noted, that a patient who has had any one of them is predisposed to infections that cause pyelonephritis.

Bed Rest for Some. Treatments are as varied as the forms of disease. In glomerulonephritis, a low-protein, low-salt diet, sometimes with sweet syrups and fat emulsions added, is often recommended. So is bed rest. Cortisone-type hormones do little good. Penicillin is no cure, but may be used to prevent recurrences in susceptible patients. Nephrotic syndrome patients, by contrast, usually get considerable benefit from cortisone; they, too, frequently need a low-salt diet—but with plenty of protein. And for them, bed rest is less important.