What is the cause of hypokalemia

Hypokalemia is a common medical disease in clinical practice. Severe hypokalemia may cause many complications and even be life-threatening. There are many causes of hypokalemia, the main one being improper diet, which leads to reduced potassium intake. So be sure to pay attention to your potassium intake.

1. Reduced potassium intake (30%):

Generally, the diet is rich in potassium, so as long as the body can eat normally, potassium deficiency will not occur. Patients with gastrointestinal obstruction, coma, and those who fast for a long time after surgery cannot eat. If these patients are given intravenous nutrition without potassium supplementation or insufficient potassium supplementation, potassium deficiency and hypokalemia may occur. However, if insufficient intake is the only reason, the degree of potassium deficiency may not be very serious within a certain period of time due to the potassium conservation function of the kidneys. When potassium intake is insufficient, urinary potassium excretion can be reduced to below 20mmol/L within 4 to 7 days, and to 5 to 10mmol/L within 7 to 10 days. Normal urinary potassium excretion is 38 to 150mmol/L.

2. Potassium loss through the gastrointestinal tract:

This is the most important reason for potassium loss in children. It is common in patients with severe diarrhea, vomiting and other conditions accompanied by a large loss of digestive fluid. The concentration of K+ in feces can reach 30-50mmol/L during diarrhea. The potassium lost with feces at this time can be 10-20 times more than normal. The reason for the increase in fecal potassium content is, on the one hand, that diarrhea reduces the absorption of potassium in the small intestine, and on the other hand, the reduction in blood volume caused by diarrhea can increase the secretion of aldosterone, and aldosterone can not only increase urinary potassium excretion, but also enhance the secretion of potassium in the colon. Since the potassium content in gastric juice is only 5-10mmol/L, the loss of gastric juice is not the main cause of potassium loss during severe vomiting, and a large amount of potassium is lost through the kidneys with urine, because the metabolic alkali poisoning caused by vomiting can increase the renal excretion of potassium, and the reduction in blood volume caused by vomiting can also promote the renal excretion of potassium through secondary aldosterone increase.

3. Transfer of extracellular potassium into cells (20%):

When extracellular potassium shifts into cells, hypokalemia may occur, but the total potassium content in the body does not decrease as a result.

① Hypokalemic periodic paralysis: During an attack, extracellular potassium shifts into cells. It is a familial disease.

② Alkali poisoning: Intracellular H+ moves to the outside of the cell to play a compensatory role, and at the same time, extracellular K+ enters the cell.