Above is the urinary organic acid test. Urinary organic acids are measures of metabolites of intestinal bacteria that are released into the bloodstream. There are several other urinary markers as well, including urinary neurotransmitter metabolites.
Relevant to acne, there is a vitamin C deficiency (vitamin C excretion = 0). Vitamin C is important for collagen formation and skin structure. Collagen/gelatin supplementation is an interesting avenue for healing acne scars. Elevated cortisol (the stress hormone) causes a breakdown of collagen into amino acids, thus leading to a loss of skin structure.
There are markers for bacterial dysbiosis. Arabinose is elevated, which is a marker for yeast overgrowth. Acne patients tend to have dysbiosis. This may be due to the traditional route of using antibiotics for acne (very short-sighted approach!), or it may have something to do with lack of essential fatty acids allowing for intestinal permeability (which wouldn’t inherently cause bacterial overgrowth AFAIK). Either way antibiotics should not be prescribed anymore for acne. If you want to go the antibacterial route, use coconut oil for caprylic acid and lauric acid, or ideally get your fatty acid profile done and get them into optimal zones, and the problem may resolve itself.
I used to look forward to not having acne due to this: http://www.popsci.com/science/article/2010-04/nano-bombs-deliver-bacteria-killing-therapy-acne, but now I realize how silly that is when you could simply take coconut oil and over time reap the benefits of the systemic effects as well. A lot of these researchers are more interested in making $$ by formulating patentable compounds, so keep that in mind when going through research articles and constantly try to figure out the integrative approach.
Also, as far as neurotransmitters go, I had high levels of dopamine compared to norepinephrine. Norepinephrine is the downstream metabolite of dopamine (by the enzyme dopamine decarboxylase). Copper is needed for this conversion. I had low plasma copper levels, due to long-term zinc supplementation. Zinc in high doses is recommended by many acne sites and practitioners, but be vigilant to not overdo it in either direction. Keep a 15 mg to 1 mg Zinc to copper ratio through supplements AND diet. Ideally, TEST TEST TEST. That is the best way to know what your levels are and avoid problems downstream.