HOUSE: Misleading Lab Results

Well, the television writers are back at their word processors, the actors are back on set, and so now I've got to get back to work and share my impressions about this latest episode of House titled "No More Mr. Nice Guy."

Just as a quick aside, I couldn't help notice that the opening scene involved striking nurses with picket signs hauntingly similar to the Writers' Guild of America placards - coincidence?

This week's puzzle involves an overly friendly guy named Jeff. He works around lots of cleaners and solvents. House discovers him in the Emergency Room. He has been sitting patiently for hours for a fainting evaluation. Jeff also has a history of dysgeusia (impaired taste) wherein everything he eats taste likes lemon meringue pie.

House is convinced that Jeff's peaceful, noncomplaining demeanor indicates occult pathology. In short, healthy people are not so placid. Since House is a lumper (tends to attribute most of a patient's symptoms to one central disorder) Jeff's demeanor and unusual taste phenomenon share a common cause.

Untreated syphilis becomes a central diagnostic consideration. If the bacterium involves the brain (neurosyphilis) there can be changes to mood, mentation, and motor skills. Blood is drawn and Jeff's serology tests are positive for syphilis. Shortly thereafter a tube of House's blood is inexplicably tested and it, too, is positive for syphilis.

We can skip the moral outrage concerning unauthorized testing of co-workers. Hey! This team performs routine home invasions of its patients to search for clues. "Mrs. Kettle, have you met Mrs. Pot?"

It's good to see that the writers have not lost their stride, pacing Jeff's various ICU crashes to precede each jumbo commercial block. Eventually it is discovered that House's sample was not his blood (meaning someone is still roaming Princeton with undiagnosed syphilis!) Jeff becomes hostile and mean-spirited while his overall medical condition continues to deteriorate. Repeat brain imaging reveals new lesions suggestive for a different kind of infection, a bug that could generate positive syphilis serology. We call this finding a false positive (tests confirms presence of syphilis where there is none).

Lots of medical conditions can generate a false positive syphilis test. Alternate testing like PCR (gene amplification) and selective immunoassays can help clinicians get to the truth. In Jeff's situation, he had contracted Chagas' Disease (a bloodborne protozoan that favors the heart and brain) while living in Central America many years earlier. It remained undetected for over a decade and insidiously caused his mood and taste abnormalities. Antiparasite medical therapy will eliminate the infection and hopefully normalize his central nervous system.

Here's a helpful take-away point: Whenever a physician informs you of unexpected lab results don't hesitate to ask if a second round of confirmative tests or alternative studies would be beneficial. It is never wise to base important health care decisions on a single tube of blood, especially when it might not even be your blood!

Related Topics:

• Understanding Lab Test Results
• The Missed Diagnosis

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