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Comment by bookofjoe | Hacker News Reader

First epilepsy (dogs), now Parkinson's. Leads me (retired neurosurgical anesthesiologist) to wonder if ALL pathology has an olfactory component that, with sufficient sensitivity of instrumentation, can be detected. Perhaps we won't require a "Star Trek"-type imaging device: just stand still and let the mass spectrometer do its thing.

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I'd expect you'd still need the imaging devices for many things. An olfactory test might tell you that there is a tumor in there somewhere, for example, but to treat it you probably need precise location, size, and shape.

Years ago I saw a case study go by. Despite negative tests, an elderly wife was sure something was wrong with her husband. He turned out to have a lung abscess. I no longer recall details, but the hypothesis was she could smell the rot on his breath in bed.

Would you find that with a low dose CT scan?

See, for example, Maple syrup urine disease: https://en.wikipedia.org/wiki/Maple_syrup_urine_disease

Many early medical texts routinely used smell in diagnosis.

The right question to ask is "why wouldn't it".

The only way this wouldn't work is if there is a smell your body makes that never leaves your body. But otherwise it seems pretty reasonable that you could read offgassing as a way of detecting underlying effects.

I'm right there with you though, I bet the tricorder has a nose not a eye.

Wow so 2 whole things are able to be identified by volatile chemicals and this leads to all?!

And I wonder how people like Holmes are able to survive for >10 years. We can deliver nicotine via patch, so obviously all drugs should be delivered that way. We can measure glucose from a drop of blood so obviously it follows that all blood tests run that way.

Where is the evidence that even a small fraction of the most common diseases have such a characteristic?

He was just speculating. Also, dogs can smell cancer in humans.

Dogs have been shown to detect certain cancers at later stages (which greatly limits use as a screener.. not to mention how does the sensitivity/specificity compare to state of the art). This is not surprising since as cancers advance they cause gross biochemical changes.

The further issue diagnosing cancer/no cancer or epilepsy/no is an easy problem. But train a dog/machine on 1000 or more rare diseases. Now selectivity is an actual issue. And unless you manage to overcome that, how is all this scent stuff clinically useful?

So the original "sniffer dog" study (The Lancet 8640)[0] pretty much covers a dog sniffing out a melanoma BEFORE it got to a later stage, and saved a woman's life.

I also dont understand how training a machine would have selectivity issues. Machines dont "get trained" on one thing.

0: https://www.sciencedirect.com/science/article/pii/S014067368...

That is not a study. That is a case report written as a letter to the editor. That meets no scientific rigor at all and no generalizable conclusions can be drawn from it, it provides an anecdote for further research. It also doesn’t suggest that sniff tests would fare better compared to any other screening system for melanoma.

> Also, dogs can smell cancer in humans

...and the impending onset of dangerously low blood sugar, well before the person realizes that something is wrong. There are diabetes assist dogs available for this [1].

[1] https://www.mayoclinic.org/diseases-conditions/diabetes/expe...

This is needlessly antagonistic. Though all pathology may be a stretch, the evidence for these two was only recently convered and all new fields start somewhere. Indeed, this line of thought brought us Theranos, but also brought us so much else.

"We know Earth revolves around the Sun, so obviously all planets revolve around the sun? Ridiculous!"

Last count I saw was that we know of 4016 planets, and only 8 revolve around the sun, so...

Curiosity is the entire point of this site. Cross-examining someone on fraud charges is way over the top! Could you please review https://news.ycombinator.com/newsguidelines.html and stick to the rules when posting to HN? These include:

"Please respond to the strongest plausible interpretation of what someone says, not a weaker one that's easier to criticize. Assume good faith."

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