Some people should not drink more than a liter and a half of water per day, even in the event of strong heat and heat waves. Otherwise, there is a risk of hyponatremia, a serious and often unrecognized complication characterized by a lack of sodium.
[Mise à jour le 17 juin 2022 à 16h34] It is necessary to drink more when it is very hot as in case of heat wave to compensate for body losses from above (as perspiration increases to regulate body temperature). But some people should not drink “too much” to avoid hyponatremia.
What is hyponatremia?
Hyponatremia means the decrease in the concentration of sodium in the blood. It corresponds to a state of hyperhydration cells. The measure of the level of sodium in the blood is the natremia. Normally it is included between 135 to 145 mmol/l. In case of hyponatremia, it is less than 135 mmol/l. It can be the consequence of an excessive intake of water compared to sodium (salt) or of an excess of loss of salt compared to elimination in water.
What are the causes of a lack of sodium?
Many causes may be responsible for this, including increased losses, either digestive or in the urine, very excessive water consumption (especially during heat waves), kidney disease, hormonal or cardiac.
Who are the people at risk?
- The the elderly : they cannot compensate for too much water, especially since from a certain age perspiration is altered or even absent.
- The patients with chronic diseases : malnutrition, kidney failure, heart failure, hepatic failure, respiratory failure (cystic fibrosis), endocrine problems (thyroid, diabetes, etc.), cancers, neuropsychiatric disorders.
- Patients taking certain medications : first of all diuretics (often prescribed for high blood pressure, heart or kidney problems), but also psychotropic (neuroleptics and antidepressants).
Hyponatremia is associated with several more or less serious symptoms:
- Asthenia, nausea and vomiting.
- Edema in heart and liver failure.
- Lethargy, confusional state, convulsions and coma : these neuropsychiatric signs appear for severe acute hyponatremia. The severity of hyponatremia is linked to the occurrence of intracranial hypertension.
The diagnosis is made through a blood test.
In case of hot weather, a person at risk of hyponatremia:
- Should not hydrate excessively with water alone, it is useless and potentially dangerous, but also consume foods that provide water (watermelon, cucumber…).
- Drink while eating in a varied way, dividing meals if necessary, to maintain a sufficient salt intake for the body (bread, soups, etc.).
- Wet the skin regularly and ventilate it.
- Avoid going outside during the hottest hours.
- Have the doctor re-evaluate the low-salt diets and treatments in progress (in particular diuretics) to judge the relevance of maintaining or adjusting the doses during hot weather.
Source : “Heat wave. Hyponatremia: recommendations for populations at risk”. ARS. August 2018.