A good, timely thread.
Hyponatremia is no joke guys. Years ago I was on a rim-to-rim hike in the Grand Canyon and unfortunately I witnessed a person almost die from hyponatremia. They drank a ton of plain water during the day while eating almost nothing. Late in the day they began to stumble, then couldn't stand, then slowly their mental status declined.
We managed to get them to an aid station where a doctor started an IV and we began to dribble sodium back into them. Their altered mental status precluded oral delivery of salt, usually done with saltine crackers and Gatorade. Beware, one of the symptoms of hyponatremia is extreme nausea at the thought of eating/drinking anything so the condition itself can put you in a hole that is very hard to dig out from.
They were helicoptered out, received 7 liters of slowly administered saline at the Grand Canyon clinic, and made a full recovery. The extreme degree of electrolyte loss affected this person's cardiac performance for about 6 months. The docs at the clinic see a lot of hyponatremia and have heard all the stories. Based on this person's history, the clinic estimated the person was only hours away from going into seizures, coma, and death before we got the initial saline on board.
A key to differentiating hyponatremia from heat exhaustion/stroke (without bloodwork) is history, history, history. The patient usually has ingested lots of plain water and has eaten little or nothing (at least not enough in proportion to the water).
A big piece of info for the history is urination frequency and volume. If a person is exerting themselves to the extreme they are losing lots of electrolytes and drinking plain water replaces the water but not the salts. So this person could have hyponatremia without a history of heavy urination.
But it is possible for a person to be drinking too much for the conditions, not exerting to the extreme, and this person is slowly diluting the bloodstream due to also not eating (enough). This person often has a history of unusually frequent, clear urination during the leadup to symptoms. This is what happened in the above case.
So it is critical when suspecting hyponatremia to get a good history, either from the patient if they can provide it or one of their companions. In the above case, the patient drank almost 2 gallons of water in not-so-extreme conditions, ate almost nothing, and was peeing a ton. The group's leader did a poor job of monitoring the food/water intake of his group and this bit them hard.
IMO the advice to drink until your pee is clear is overdoing it, much like "bring water to a boil then keep boiling for 5-7 minutes". In the field if my pee is light yellow that's good. Clear pee means I'm drinking too much and wasting resources.
I want to emphasize: hyponatremia is something you must work to avoid because once you're in it, you are in deep kimchee. The condition will make it hard for you to ingest what you need, and in bad cases makes it impossible for you to stand, let alone walk out. If you are solo you are hosed. If you're in a group, you will be an immobile casualty.