Four Adages.

Four adages I learned in med­ical train­ing that I still speak of today:

“Com­mon things are com­mon.” (The alter­nate ver­sion of this that might have more appeal to zool­o­gists: “When you hear hoof­beats, think horses, not zebras.”)

This cau­tions physi­cians to remem­ber that it is more likely that the patient has a com­mon con­di­tion than a rare one. Although it is pru­dent to con­sider all the pos­si­ble diag­noses that might match a given clin­i­cal pre­sen­ta­tion, one should not seek con­fir­ma­tion for an exotic con­di­tion first.

Uri­nary tract infec­tions are more com­mon than blad­der can­cers. High blood pres­sure is more com­mon than pheochro­mo­cy­tomas.1

Once you’re sure that there are no horses present, though, then begin the search for other ungulates.

“Treat the patient, not the number.”

This is a reminder that physi­cians should treat the per­son, not lab results.

If a patient’s blood count is a lit­tle low, but she’s not expe­ri­enc­ing any symp­toms, then do noth­ing. If someone’s lithium level has been low for months, but they haven’t had any mood symp­toms, then don’t increase the dose of lithium.

This, how­ever, does not apply to all con­di­tions: Peo­ple with alarm­ing blood pres­sure num­bers often feel fine. Same thing with high blood sugar numbers.

“The longer some­one stays in the hos­pi­tal, the longer he stays in the hospital.”

Hos­pi­tals are not san­i­tary places. The longer a patient stays in the hos­pi­tal, the more likely he will develop an infec­tion that is resis­tant to mul­ti­ple antibi­otics. This leads to com­pli­ca­tions that length­ens the hos­pi­tal stay.

This also applies to staff: The longer a physi­cian stays in the hos­pi­tal (beyond her shift, for exam­ple), more things will come up that she will have to address, which will will keep her there even longer.

“When you only have a ham­mer, every­thing is a nail.”

This is a reminder to con­sider other per­spec­tives. It is also an exhor­ta­tion to recruit the minds and skills of others.

If the psy­chi­a­trist only knows how to pre­scribe med­ica­tions, then all of his patients will receive pills. The sur­geon might believe that cut­ting out the offend­ing tis­sue is the only solution.

One won­ders when these phrases first came into being. It’s an oral his­tory that physi­cians pass along every July.


  1. A pheochro­mo­cy­toma is a rare tumor of the adrenal gland, which is a small lump of tis­sue that sits above the kid­neys.