What is water intoxication? Be careful of renal dysfunction

Water intoxication occurs when the body takes in too much water, also known as dilutional hyponatremia. Water intoxication is relatively rare in clinical practice, so most people don’t know what water intoxication is. Generally speaking, the factors that cause water intoxication may also be caused by renal dysfunction.

(A) Excessive secretion of ADH

It can be seen in fear, blood loss, shock, acute infection (such as pneumonia, toxic dysentery, etc.), use of analgesics (such as morphine, pethidine), or stress stimuli such as pain, injury, and surgery. Increased ADH secretion after surgery usually lasts for 12-36 hours, or longer. In this case, excessive intake of electrolyte-free solutions such as glucose can easily lead to water poisoning. In addition, patients with late-stage hypothyroidism who develop partial fluid edema can also increase ADH secretion through stimulation of pressure receptors, and abnormal ADH release may also occur in cases of adrenal cortex insufficiency.

2. Renal dysfunction

During the oliguria and anuria stage of acute renal failure, the dilution and concentration functions of the kidneys are impaired. Excessive water intake at this time can easily lead to water intoxication. In addition, if renal blood flow is insufficient or glomerular blood perfusion is severely reduced for any reason, excess water cannot be excreted and water intoxication is likely to occur in combination with hypotonicity.

3. Disorders of water and sodium metabolism

In patients with severe sodium deficiency (hyponatremia) or hypotonic dehydration, the extracellular fluid is already in a hypotonic state. Through compensation, the renal tubular reabsorption of water and uranium has increased. At this time, excessive water intake may cause water intoxication. Some have even suggested that in hypertonic dehydration, due to cellular dehydration, water intoxication may sometimes occur if salt-free fluids are rapidly and massively infused. Therefore, no matter how high the hypertonic dehydration is, it can only be treated by infusing hypotonic fluids.

(IV) Insufficient renal drainage function

During the acute and chronic renal insufficiency oliguria stage, the kidney's drainage function decreases sharply. If the water intake is not restricted, it may cause water retention in the body. In severe heart failure or cirrhosis, due to the decrease in effective circulating blood volume and renal blood flow, renal drainage is also significantly reduced. If the water load is increased, it can easily cause water intoxication.

(V) Others

In the late stage of hypotonic dehydration, the extracellular fluid shifts into the cells due to the hypotonicity of the extracellular fluid. It can cause intracellular edema, and if a large amount of water is input at this time, it can cause water intoxication.