This question came to mind after reading this article. The article speaks of inducing sweating to determine, by a roundabout fashion, the amount of salt therein. I'm no medic but I find myself wondering whether sweat may be used directly to measure any other chemicals secreted by the body.
For instance:
If one's kidney/liver were to suffer some malady would the body attempt to discharge some additional waste through one's sweat
What chemicals may be detected by analysing sweat?
Cystic fibrosis diagnosis. Here is a link to a paper describing the use of β-adrenergic sweat secretion as a diagnostic test for cystic fibrosis.
Anti-cancer therapy and its effectiveness. This report seeks to determine the levels of the anti-cancer drug sunitinib and its active metabolite N-desethylsunitinib in sweat.
I'll add others later.
Here's a 2004 study looking at a particularly unpleasant sulfury compound produced by bacteria in contact with sweat. It's interesting that the enantiomer of the malodorous compound had a grapefruit-like smell.
This paper puts forth the idea that sweat, which contains lactate, lactic acid, urea (of course) and amino acids, can be used in forensics.
I can't provide any real technical details, but I recently watched a documentary in which a team demonstrated a new type of blood sugar sensor that could be simply swabbed against sweat. They were trialling it as a non-invasive option that paramedics could carry, for use on unconscious patients as a means of checking for signs of diabetic shock. They mentioned that it only required a minimal sample; a swab of the palm of the hand was sufficient to gain a decent reading.
I'm unsure as to the mechanism of the device - it could well have been direct measurements of sugars or sugar by-products in the sweat, or it could have been looking for other chemicals associated with abnormal blood sugar levels.
