Most people do not to have oxalate crystals in the urine. They can be seen in a urine specimen in someone has ingested anti-freeze. People get deathly ill when this happens. Now this is not the same as calcium oxalate crystals which a commonly forms when a urine sample sits and is allowed to settle. It's like chemistry class. When certain ingredients sit in a cup over a period of time crystals may form.
Urine can range in shades of color from light yellow to almost clear and darker. This is normal. Your kidneys can make the urine more or less concentrated based on how much water or fluids a person drinks.
Risk factor for lichen simplex includes constant irritation that is persistent to the genitalia such as perfumes, detergents, fragrant items or history of trauma. If urine and fecal matter sit in this area long enough a person can become irritated.
What tends to occurs is from whatever the cause is itching. When scratching of the area continues it tends to exacerbate the irritation. So the result is the more you scratch the more you itch the more your scratch.
The area tends to burn because of the chronic irritation or inflammation that is present. If scratching and rubbing of the area is continued it is easy for the skin to have small areas or abrasions. So urine which has salt in it will burn at times because it's literally putting salt in a wound.