Very low urinary sodium excretion is a significant clinical manifestation of hyponatremia. The normal value of blood sodium is 142 mmol/L (135-145 mmol/L), and blood sodium below 135 mmol/L is considered hyponatremia. Urinary sodium volume: normal adult 70-90 mmol/24h, which is about 4,1-5,3 g of sodium chloride. if urinary Na+. Prevention methods for very low urinary sodium excretion: 1. Acute severe sodium deficiency can be replenished at 2/3 of the calculated amount, at a rate of 1 to 2 mmol/L blood sodium concentration per hour, and 24h uniformly. Chronic sodium loss can be replenished in 48h. For those with stable circulation, it is contraindicated to correct hyponatremia too quickly; otherwise, it may lead to osmotic demyelination syndrome, paraplegia, tetraplegia, aphasia, congestive heart failure and cerebral edema. 2.Chronic sodium loss hyponatremia is mostly seen in various wasting diseases, where sodium loss of the body includes not only intra- and extracellular fluid sodium, but also bone sodium. Should pay attention to the amount of sodium supplementation to reach the conventional calculation of the amount of two times, the speed of sodium supplementation should not be too fast, while supplementing potassium, magnesium is better.