Low body mass (infants) It can be very easy for children under one year old (especially those under nine months) to absorb too much<unk> . Because of their small body mass, it is easy for them to take in a large amount of<unk>  relative to body mass and total body sodium stores. Endurance sports Marathon runners are susceptible to<unk>  if they drink too much while running. This is caused when sodium levels drop below 135 mmol/L when athletes consume large amounts of fluid. This has been noted to be the result of the encouragement of excessive fluid replacement by various guidelines. This has largely been identified in marathon runners as a dilutional hyponatremia. A study conducted on runners completing the 2002 Boston Marathon found that thirteen percent finished the race with hyponatremia. The study concluded that the strongest predictor of hyponatremia was weight gain while racing (over-hydration), and hyponatremia was just as likely to occur in runners who chose sports drinks as those who chose<unk> . Military training Hyponatremia and other physical conditions associated with<unk>  are more often seen in those participating in military training. One US Army study found 17 trainees were admitted to hospital over a year's period for<unk>  while another found that three soldiers had died, leading to a recommendation that no more than 1-1.5L of<unk>  should be consumed per hour of heavy sweating. Overexertion and heat stress Any activity or situation that promotes heavy sweating can lead to<unk>  when<unk>  is consumed to replace lost fluids. Persons working in extreme heat and/or humidity for long periods must take care to drink and eat in ways that help to maintain electrolyte balance. People using drugs such as MDMA (often referred to colloquially as "Ecstasy") may overexert themselves, perspire heavily, feel increased thirst, and then drink large amounts of<unk>  to rehydrate, leading to electrolyte imbalance and<unk>  – this is compounded by MDMA use increasing the levels of antidiuretic hormone (ADH), decreasing the amount of<unk>  lost through urination. Even people who are resting quietly in extreme heat or humidity may run the risk of<unk>  if they drink large amounts of<unk>  over short periods for rehydration. Psychiatric conditions Psychogenic polydipsia is the psychiatric condition in which patients feel compelled to drink large quantities of<unk> , thus putting them at risk of<unk> . This condition can be especially dangerous if the patient also exhibits other psychiatric indications (as is often the case), as the care-takers might misinterpret the hyponatremic symptoms. Iatrogenic When an unconscious person is being fed intravenously (for example, total parenteral nutrition) or via a nasogastric tube, the fluids given must be carefully balanced in composition to match fluids and electrolytes lost. These fluids are typically hypertonic, and so<unk>  is often co-administered. If the electrolytes are not monitored (even in an ambulatory patient), either hypernatremia or hyponatremia may result. Some neurological/psychiatric medications (Oxcarbazepine, among others) have been found to cause hyponatremia in some patients. Patients with diabetes insipidus are particularly vulnerable due to rapid fluid processing. Pathophysiology== At the onset of this condition, fluid outside the cells has an excessively low amount of solutes, such as sodium and other electrolytes, in comparison to fluid inside the cells, causing the fluid to move into the cells to balance its osmotic concentration. This causes the cells to swell. The swelling increases intracranial pressure in the brain, which leads to the first observable symptoms of<unk> : headache, personality changes, changes in behavior, confusion, irritability, and drowsiness. These are sometimes followed by difficulty breathing during exertion, muscle weakness & pain, twitching, or cramping, nausea, vomiting, thirst, and a dulled ability to perceive and interpret sensory information. As the condition persists, papillary and vital signs may result including bradycardia and widened pulse pressure. The cells in the brain may swell to the point where blood flow is interrupted resulting in cerebral edema. Swollen brain cells may also apply pressure to the brain stem causing central nervous system dysfunction. Both cerebral edema and interference with the central nervous system are dangerous and could result in seizures, brain damage, coma or death.
Water intoxication
Flint water crisis
Hyperosmolar syndrome
Dehydration
Diabetic ketoacidosis
Serkal syndrome
Alcohol intoxication
Alcoholic ketoacidosis