Introduction to hyponatremia

The normal value of blood sodium is 142 mmol/L (135-145 mmol/L), and the hyponatremia is lower than 135 mmol/L. Urine sodium content: normal adult 70 ~ 90mmol / 24h, about sodium chloride 4.1 ~ 5.3g. If the urine Na+<34.19mmol/L or absent, it indicates that Na+ is absent in the body. Hyponatremia is a clinically common electrolyte disorder, and sodium and water are closely interdependent. The blood sodium concentration is lowered, and the osmotic pressure of plasma is also generally lowered, so hyponatremia is also called hyponatremia hypotonic syndrome. The plasma sodium concentration that should be clearly determined does not indicate the total amount of sales in the body and the distribution of sodium in the body. The measured decrease in plasma sodium concentration is not sufficient to confirm sodium deficiency in the body. For example, in the case of dilute hyponatremia, the total amount of sodium in the body does not decrease, and sometimes even increases. However, since the increase in water in the total solution is more pronounced than the increase in sodium, the plasma sodium concentration is lowered. There are many methods for classification and classification of etiology. The changes of extracellular fluid volume are not considered from hyponatremia. The more complete causes are classified as follows: (1) Loss of sodium and hyponatremia with loss of water, but through water The intake or body compensation makes the salt loss greater than the water loss, so the sodium loss hyponatremia is hypotonic, including hypotonic dehydration, ie hyponatremia with decreased extracellular fluid volume. Common in vomiting, diarrhea, gastrointestinal drainage, large loss of gastrointestinal digestive juice, a lot of sweating, severe burns, large amount of exudate, drainage of pleural effusion, ascites, renal dysfunction, adrenal insufficiency, ADH secretion abnormal syndrome, diabetes Acidosis, a large number of diuretics and so on. (B) Dilute hyponatremia refers to excessive water retention in the body, the total amount of water is too much, the total amount of sodium in the body is unchanged or slightly increased, due to blood dilution and hyponatremia, which is also hypotonic. Common in mental polydipsia, patients drink plenty of water, the kidneys are too late or can not be completely discharged; brain diseases, malignant tumors, lung lesions, and surgical stimulation, trauma and other stress stimulation, abnormal increase in ADH secretion; and hypothyroidism, etc. . The blood volume of patients with dilute hyponatremia can be slightly increased, so the urine sodium is not reduced. The osmotic pressure of >20mmol / L can be reduced from normal 285 mmol / L to 240 mmol / L, and serum sodium is usually 130 ~ 140. Mmmol / L or lower. (C) the increase in the total amount of hyponatremia, the primary factor is sodium retention, and water retention > sodium retention, and lead to lower blood sodium, also known as swelling hyponatremia. Common in congestive heart failure, cirrhosis, decompensation, nephrotic syndrome and acute, chronic renal failure. This type of hyponatremia is mostly gradual and often maintains a new balance under certain hypotonic conditions. Patients often have hypokalemia, hypoproteinemia, low urine output, urinary sodium often <20 mmol / L, high urinary potassium, high urine relative density. (4) Asymptomatic hyponatremia is mainly seen in chronic wasting diseases such as severe tuberculosis. Advanced cancer, cachexia, malnutrition, etc., this mechanism is not clear, so it is called idiopathic hyponatremia. The nomenclature of asymptomatic hyponatremia is inadequate because many cases of early or slow progression of hyponatremia are asymptomatic. (5) Pseudohyponatremia, hyperlipidemia, hyperproteinemia, resulting in a large amount of highly permeable substances in the blood such as hyperglycemia and mannitol. The blood sodium concentration is lowered, which is called pseudohyponatemia. In general, when the total serum lipid is 60 g/L or the total serum protein is 140 g/L, the blood sodium concentration is reduced by about 5%. (6) Cerebral salt depletion syndrome is caused by inferior colliculus or brain stem injury, leading to neurological regulation of the kidney, osmotic diuresis in the distal renal tubule, and increased sodium, chlorine and potassium in the urine, and blood Lower in the middle. Clinically, hyponatremia is sometimes a single cause, but it is often complex. When analyzing the etiology and pathogenesis of hyponatremia, it needs to be fully understood and considered. For the treatment of hyponatremia and dilute hyponatremia, see "hypotonic water loss", "excessive water and water poisoning". Therapeutic hyponatremia is mainly for the treatment of primary disease. Mechanism loss of body fluids is often accompanied by loss of water with certain solute (electrolyte). For example, diarrhea can cause a large amount of digestive juice to be lost. The digestive juice is basically isotonic. Although the loss of isotonic fluid does not directly cause hypotonicity or low Natriuresis, but reduced blood volume can cause thirst, after inhalation or infusion of hypotonic fluid, hypotonic or hyponatremia occurs. The first is caused by hypotonic extracellular fluid. The main reaction of the body during hypotonic is water diuretic to discharge excess water. The discharge of water is mainly done by the kidney. The mechanism is as follows: 1. The upper osmotic pressure receptor is accepted. Stimulation reduces the release of ADH in the posterior pituitary. 2 There is enough liquid to be filtered out through the glomerulus and reach the dilution section of the renal tubule, ie the ascending branch of the myelin and the distal convoluted tubule. 3 The function of the tubule dilution section is normal, and the reabsorption of sodium is ensured by the action of aldosterone. Since ADH reduces the permeability of the distal renal tubular epithelial cells to water, the water absorption is reduced. As a result, a large amount of moisture is discharged. The kidney's drainage capacity can reach 15-20L per day. Kidney regulation of water and sodium is essential. If any cause causes urinary dilution disorder, such as abnormal increase in ADH release, glomerular filtration reduction, and impaired renal dilution function, water will be stored in the body. On the other hand, hypotonic extracellular fluid will inevitably lead to the exchange of fluid between the intracellular fluid and the extracellular fluid, and maintain a new balance. Because the kidneys are against water. The regulation and mobilization of salt metabolism requires a certain period of time. Therefore, the extracellular fluid is seriously hypotonic or the water is stored too fast, which will cause the extracellular fluid to transfer a large amount of water into the cells, causing intracellular edema (water poisoning). The early symptom of the diagnosis of hypernatremia is thirst. In severe cases, the brain cells are dehydrated and mainly manifest symptoms of the nervous system such as irritability, lethargy, hyperreflexia, increased muscle tone, and later convulsions, convulsions, and coma. Hyperkalemia: serum potassium is higher than 5.5mmol / L. Muscle weakness can occur in the early stage, severe abdominal reflexes disappear, muscle paralysis, and even respiratory muscles are paralyzed. The early circulatory rate of the circulatory system is slow, severe arrhythmia, and even ventricular fibrillation leads to cardiac arrest. Patients with mild hypokalemia often have no obvious clinical signs, and may have weak body weakness, soft limbs, weakened or disappeared biliary reflexes, severe respiratory paralysis and cardiac dysfunction m heart rhythm disorder, heart enlargement, and even heart Stopping in. Hypercalcemia: When serum protein is normal, serum calcium is increased by >2.75mmol / Read more...