Smells as a Diagnostic Clue
Consider this post "part II" in response to faithful
reader of our student blog, Mark Behar of Milwaukee, Wisconsin. His
challenged me to follow up on the use of odors and smells to
diagnose, or at least give us clues to how best to treat our patients'
underlying pathologies. I can't refuse a good challenge. Thanks, Mark, because
you made me do a little research that no doubt will help me become a more
First, to help our learning, a brief case study:
An 8-day-old white male infant presents to your ED
with a 4-day history of lethargy and vomiting and the mother complains, "He
smells bad even after I bathe him and he won't eat." The infant was full term
and weighed 6 lb. 5 oz. At the visit today the infant weighs 5 lb 12 oz. The
mother states he has had no wet diapers for 2 days. He is lethargic and vomits
twice while in the ER. He will not take a bottle.
Family and medical history are unremarkable. Child
lives at home with two parents and healthy 2-year-old sister.
On physical exam, the infant appeared dehydrated
with sunken eyes, dry mucous membranes and no fat stores. The infant smells
like sweaty feet or rotten cheese.
After a full workup with lab tests, imaging and
genetic testing, this patient is admitted to the NICU. You emphasized to the
admitting NICU team that they should seek genetic testing as soon as possible
because the smell of the child could indicate an underlying genetic disorder. The
NICU team follows your suggestion, which helps expedite the patient's diagnosis:
isovoleric academia (IVA), a rare autosomal recessive disorder that is pathognomonic
for the "sweaty feet, cheese" smell.
This patient has decreased production of the enzyme
that breaks down leucine. Isovoleric acid builds up, resulting in its secretion,
which leads to the odor on the skin and other effects of metabolic acidosis such
as coma and eventual death. Is there any hope for this baby? Of course. The
mother is instructed on a very specific low protein diet to avoid leucine as
well as administration of carnitine and glycine, which research has shown will help
metabolize the acid.
After a week-long admission and follow-up with a
geneticist and dietitian, the patient returns home. By 1 month, he has returned
to his birth weight. This child's life will be extremely complicated by this
disease, but misdiagnoses could have been fatal.
So, back to Mark's point: smells can save a life. Of
course, it was actually all the labs and the genetic testing that proved the diagnosis but there's some
support that following your nose as a practitioner may not be a bad idea.
IVA is very rare. Most diseases pathognomonic with
an odor are, but a few interesting ones I came across to complete our
Nicotine addiction. (Just kidding, but we all know it's true.)
PKU = Musty, locker room towels
Maple syrup urine disease = (you'll
never guess) maple syrup
Hypermethioninemia = breath smells like
Cystinuria = urine smells like rotten
Methionine malabsorption = malt or hop
Cyanide poisoning = breath smells like
DKA = breath smells fruity
Kidney failure = breath smells like
Ileus = breath smells like solid human waste
Tuberculosis = reported to smell like
Malignant melanoma = smells like
Smelling down your patients is never a walk in the
park to smell the roses because usually sick people don't smell like roses. For
example, I came across a study that money could not pay me to participate in:
smelling the elderly's incontinence pads to detect bacteriuria. It was only 33%
accurate. I wonder if that was just the fault of the researcher's smell
fatigue. I can't blame them.
In medicine, a reality of our jobs is billing: we
have to make money and prove stuff with our money-making tests. For this
reason, diagnosing based on smell is tricky because our accuracy is rather
pathetic if used alone without other costly tests.
Although we humans aren't always the most accurate
sniffers, dogs, who have long been known to exceed humanity's abilities in a
myriad of skills, prove to be super smellers in medical diagnosing. There's
some other interesting research about dogs being able to rat-out a patient with
schizophrenia from their smell. A recent Wall Street Journal piece highlighted
the role of dogs in pediatric Type I diabetics to assist families in avoiding
These dogs don't come cheap and cost between
$18-20K. I'm jealous of our furry cousins because if I could make that kind of
money smelling, my student loan debt would be so much less daunting. Dogs are
definitely where more researchers are putting their efforts, but don't let this
dissuade you from smelling.
This brief post just scratches the surface of all
that lies under the power of our noses. I suggest you do some follow-up
research, especially with regards to "aroma therapy" for reminiscence. You
never can tell what you'll smell along the way.
et. al. The scent of disease: volatile
organic compounds of the human body related to disease and
disorder. Journal of Biochemistry
Review: 2011;150(3):257-26. Available
S.J., Paur R., Lindseth G. Urinary Tract
Infections: does the smell really tell?
Journal of Gerontologic Nursing.
- Pavlou, AK.
Sniffing out the truth: clinical diagnosis using the electronic nose. Clinical Chemistry Laboratory Medicine. 2000 Feb;38(2):99-112.
Available at: http://www.ncbi.nlm.nih.gov/pubmed/10834396
et. al. A neonate with
hyperammonemia. Lab Medicine. 2005 Jan; 36 (1). Available at: http://labmed.ascpjournals.org/content/36/5/292.full.pdf
K. Service Dogs Pick up Scent of
Diabetes Danger. The Wall Street
Journal. 2012 Dec 10. Available from: http://online.wsj.com/article/SB1000142412788732400110457816342312970336.htm