What causes symptoms of low potassium?

Potassium is an important nutrient in our body. If the body lacks potassium, the secretion of hormones will be affected, and the patient's health will naturally be indirectly affected. There are many reasons for low potassium in the body, such as insufficient potassium intake, picky eating, gastrointestinal loss, etc. It is recommended that patients find out the cause before receiving treatment.

(1) Acute potassium-deficit hypokalemia (acute potassium-deficit hypokalemia) is referred to as acute hypokalemia. Due to increased potassium loss or insufficient potassium intake, the serum potassium ion concentration drops below the normal level in a short period of time. At the same time, the body's potassium content decreases, making various types of arrhythmias or muscle weakness more likely to occur.

1. Reasons

1) Insufficient intake

(1) Fasting or anorexia. Since both normal diet and enteral nutrition diet contain a lot of potassium (as mentioned above, the K+ concentration in most cells is more than 30 times that outside the cells), and the kidneys have a strong ability to retain potassium, hypokalemia is not likely to occur with a general reduction in diet. However, it will occur when there is severe lack of food intake and potassium is deficient in intravenous fluid replacement. It is mainly seen in patients who cannot eat or who have severe food deficiency due to coma, postoperative, gastrointestinal diseases, etc. Patients with chronic wasting diseases have less muscle tissue, less overall potassium storage, and insufficient food intake, and are also prone to hypokalemia. People with heart failure, liver cirrhosis, blood diseases, and tumor diseases are prone to severe food insufficiency.

(2) Picky eating

Some patients with severe picky eating habits may also develop hypokalemia.

2) Increased loss

It is mainly seen in patients with acute loss of various secretions; or in patients with massive diuresis and insufficient potassium supplementation, in which case hyponatremia and hypochloremia often coexist.

(1) Loss through the digestive tract

Because the potassium concentration in various digestive juices is almost always higher than that in plasma, and the secretion amount is larger, and the secretion amount is even greater under the stimulation of pathological factors such as inflammation; once such diseases occur, the amount of food intake will be significantly reduced, or even completely fasting, so digestive tract diseases are very prone to hypokalemia and are easily combined with disorders of other electrolyte ions. Since the composition of digestive juices in different parts of the body is different, the types of combined other electrolyte disorders are also different. For example, the Cl- and H+ content in gastric juice is high, so vomiting and gastric juice drainage are easily complicated by hypokalemia, hypochloremia and metabolic alkali poisoning. The concentration of HCO-3 in intestinal fluid is high, so drainage of the bile duct and pancreatic juice, as well as diarrhea, are easily complicated by hyperchloremic acidosis. Hypokalemia may also occur in patients who use laxatives inappropriately.

(2) Loss through the kidneys

Various primary or secondary renal tubular dysfunctions can easily cause excessive potassium loss. Diseases or factors other than the kidneys can also increase renal potassium excretion, mainly the following problems. ① Proximal or distal renal tubular acidosis due to various reasons of renal tubular function damage can cause severe hypokalemia due to reduced potassium reabsorption or increased secretion. Other drugs such as aminoglycoside antibiotics, immunosuppressants (especially routinely used in organ transplant patients), antiviral drugs or chronic potassium deficiency and magnesium deficiency can easily damage the function of the renal tubules and cause hypokalemia. The renal function (creatinine) of such patients is usually normal, and even urine protein is negative, but they may have combined deficiencies of other electrolyte ions, diabetes insipidus, metabolic acidosis, etc. Therefore, it can be called "latent renal tubular dysfunction", which is actually abnormal renal tubular reabsorption or secretion function. ② The polyuria period of renal insufficiency is often accompanied by a large loss of electrolytes, such as sodium and potassium, resulting in hypokalemia.

2. Pathophysiology and clinical manifestations

(1) Neuromuscular system ① Skeletal muscle weakness and paralysis: Hypokalemia, the concentration difference of K+ inside and outside the cell increases, the negative value of the resting potential increases, the triggering threshold of the action potential increases, the excitability and conductivity of the nerve-muscle decreases, and muscle weakness occurs. Muscle weakness generally starts from the lower limbs, especially the quadriceps, and manifests as difficulty walking and unstable standing. As hypokalemia worsens, muscle weakness worsens and affects the trunk and upper limb muscles until it affects the respiratory muscles and respiratory failure occurs. Generally, muscle weakness may occur when the serum potassium concentration is lower than 3 mmol/L, and paralysis may occur when it is lower than 2.5 mmol/L, and respiratory failure is also likely to occur. In patients with impaired lung function, hypokalemia leading to respiratory failure or worsening of respiratory failure is more common, but it is easy to be overlooked clinically. ② Smooth muscle weakness and paralysis: manifested as abdominal distension and constipation. In severe cases, paralytic intestinal obstruction and urinary retention may occur.