"dark urine" can be a sign of liver problems and/or viral hepatitis. Is there an odd smell? Do you have any other symptoms? light stools? Feeling over tired? Any spider angiomas or "red spots" showing up on your body? Get checked for hepatitis a b and c. It is a simple blood test and many people have it and have no risk factors. The doctor can also do a liver enzyme test, another simple blood test, to check for other liver issues.
If you drink alcohol I strongly advise you to stop until you figure out what this is.
I didn't make myself quite clear it would seem. Yes, the color of cola can be from blood, but that blood is from the liver or bile ducts. The color would come from the breakdown of the iron in the red blood cells giving it a dark brown or cola color. If the urine is red in color it is blood from the kidney, ureter, or bladder, or menses. Whenever urine is any color other than a shade of yellow, and dyes, meds, and menses cannot be the cause, a visit to the doctor is called for. A simple and fast UA test can be done in the office to diagnose the presence of blood. Since your problem has already "cleared up" I would mention it to the doc on the next visit. If it returns, go to the doc as soon as possible.
Brown urine can indicate blood- search for blood in urine.
"When there is enough blood to be visible, the urine may look pinkish, red, or smoky brown (like tea or cola). This is called gross or frank hematuria. It takes very little blood in urine to be visible
Brown or coke colored urine usually indicates a problem with the liver or bile ducts. It can also occur because of the consumption of a dye in food. Blood in the urine is always red or orange.
If there is any brown at all you should go to the doctor- it could be blood in your urine.
Make sure you are drinking enough water. It could of been dehydration. sometimes blood can be present if a blood vessel broke thie will happen. If still having trouble see your md.
You may have been dehydrated. If drinking more fluid has cleared it up, then that's probably what it was.