The Pisse-pot Prophet
Medical prognosis and its discontents
Posted Jun 24, 2011
Modern medicine has more in common with the past than we like to think. Even in the 21st century, the treatment of illness is to some extent an art, not a science. Cognitive errors, magical thinking, and the unruly emotions of doctors and patients-- all affect clinical reasoning.
Imagine the modest home of a physician on the outskirts of London in the 1670s: dark paneled interior, leaded windows, sparse furnishings. Someone is knocking loudly at the door; the doctor stumbles out of bed in his cap and gown to greet a messenger bearing a urine sample in a "piss pot." It's possible that the pot is a matula, a vessel shaped to resemble the bladder, with parts of the curved glass corresponding (or so it's thought) to regions of the human body. The doctor carefully places the pot on the windowsill, but he glances at it only fleetingly. He tells the messenger the urine needs to settle.
Then follows a typical exchange: How long has the patient been sick? If the answer is a day or a week, then most likely a violent or acute illness, probably attended by fever; if many weeks or months, then a chronic condition. Before the patient was ill, what were his customary activities? If the sick person were the sort to wander up and down the town, then male; accustomed to stay at home, female. On this occasion, the doctor's questioning reveals that the patient is a woman, sick with a violent fever.
Now taking up the urine with the pretense that it has had time enough to reveal its true properties, the physician predicts that the patient will die unless such and such speedy remedies be used. For him it's a win-win situation. If the party dies, he'll be hailed for his prophetic powers; if the patient lives, he'll get credit for a miraculous cure.
These passages come from Thomas Brian's "The Pisse-prophet, or, Certain Pisse-pot Lectures" published in 1679. His aim is to discredit "uromancy," the 17th century craze for arcane, elaborate, fanciful interpretation of urine. What we now call urinalysis was then the favorite diagnostic tool of physicians, used also by "leches," nonprofessionals who used color, consistency, sediment, and other features to prophesy not just the course of a disease but (sometimes) the patient's entire future. Forget physical exam and history--forget the patient altogether. Just bring on the urine.
Brian's Pisse Pot satire threw urinalysis out of favor for the next several hundred years.
In essence, he threw the baby out with the bathwater, because of course the urine does--and did, even before the advent of laboratory science and white cell counts-reveal pathology. At various points in the medical literature of the past, from antiquity to the Renaissance , there are descriptions of proteinuria, hematuria, polyuria, sediment, gravel, as well as the occasional speculation about causes like nephritis or diabetes. But the dominant theory to explain these urinary signs was Galen's theory of the physiological humors, linking four bodily fluids-black bile, yellow bile, blood, and phlegm-to the elements of earth, air, fire, and water, as well as to governing planets. Disturbances in the urine reflected disturbances in the humors. With this erroneous paradigm of causation, medical treatment was pretty much hit-or-miss.
Thomas Brian himself, famous in his time for the Pisse-Pot Lectures, comes across as a somewhat cynical, though savvy, expert in doctor-patient relations. He knows some of his patients are hypochondriacs and some are what we'd now call noncompliant; some are going to die (whatever he does) and some are going to live (whatever he does). He knows his customers want an answer (preferably an optimistic one) even when there is no answer. From a reading of the piss pot, they expect diagnosis and, even more important, prognosis: what will happen next? Medicine is, in part, the art of predicting the future. And prophesying is a tricky business, inviting unjust blame on the one hand, extravagant credit on the other.
Today, the piss pot has been replaced by laboratory values, Galen's humors by an understanding of glomerular filtration rate and inflammatory processes. But magical thinking-the push to treat on the basis of inadequate evidence, the imaginative (or fantastic) interpretation of signs-persists despite our best efforts to nail the facts. Recent examples of "magical" medicine include things like glucosamine, a molecule that's a building block of cartilage. Found in pharmacies and advertised as improving joint health, glucosamine will, in fact, do nothing for you because it can't be absorbed in the active metabolic process that builds cartilage. Likewise, collagen, marketed as an anti-wrinkle miracle that will plump up your face, returning you to a youthful softness, can't penetrate the epidermis to reach the deeper layers where active collagen is generated.
It's not just false cures and "speedy remedies" that are still with us. False interpretations are still around, too. Take the identification of DCIS, ductal carcinoma in situ, via mammogram, which led to many surgical procedures-biopsies, lumpectomies, even mastectomies. Reading the mammogram has turned out to be almost as suspect as Brian's reading of the urine. Recent studies have shown that DCIS is so slow to grow that leaving it alone is the best option. Women will have died of something else long before ductal carcinoma would ever pose a problem. Imaging artifacts leading to unnecessary procedures are generally not uncommon in our era of high-tech medicine.
The pisse pot prophet with his erroneous theories and quack predictions is a figure of curiosity and amusement. But the more things change, the more they stay the same. Mistakes and falsehoods still abound in medicine. Prognostication is still a tricky business.