How is hypokalemia tested?

Written by Li Fang Fang

Hematology

Updated on May 25, 2025

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Hypokalemia can be diagnosed by drawing 3-5ml of venous blood for biochemical and electrolyte tests. Patients with hypokalemia may experience weakness or even paralysis, hence it is crucial to actively treat by replenishing potassium. During potassium supplementation, it is also important to clarify the underlying cause of the hypokalemia in order to solve the issue from its root. Otherwise, merely supplementing potassium might result in recurring hypokalemia.

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Written by Wei Shi Liang

Intensive Care Unit

1min 1sec

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Why does hypokalemia cause abnormal acidic urine?

Hypokalemia is characterized by a reduction in the concentration of potassium ions in the extracellular fluid, which causes the transfer of three potassium ions from inside the cells to the outside, while two sodium ions and one hydrogen ion move from the outside to the inside of the cells. Due to the decreased concentration of hydrogen ions in the extracellular fluid, metabolic alkalosis can easily occur. At the same time, due to the reduction of blood potassium, the potassium-sodium exchange in the renal tubules decreases. Renal tubular cells secrete more hydrogen ions to exchange with sodium ions, and the reabsorption of bicarbonate ions increases, raising the pH value. This metabolic alkalosis increases the number of hydrogen ions inside the cells and the kidney's hydrogen secretion, thus making the urine acidic, often referred to as paradoxical aciduria.

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Written by Wei Shi Liang

Intensive Care Unit

52sec

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What medicine should be taken for hypokalemia?

The treatment of hypokalemia primarily involves addressing the underlying disease. Symptomatic treatment should avoid excessive potassium supplementation, which can lead to hyperkalemia. The principle of potassium supplementation is as follows: for mild hypokalemia, such as in patients showing clinical signs, oral potassium can be administered at 40-80 millimoles per day. For patients with severe hypokalemia, or those whose gastrointestinal tract cannot utilize potassium, with potassium levels less than 2.0 millimoles per liter, intravenous potassium can be provided. An initial supplementation rate of 10-20 millimoles per hour is relatively safe. In cases of severe hypokalemia with life-threatening clinical signs, a rapid increase to 40-80 millimoles can be achieved in a short period, but close monitoring is necessary.

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Written by Wei Shi Liang

Intensive Care Unit

1min 4sec

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Causes of hypokalemia

Potassium is one of the essential electrolytes necessary for life. Its physiological functions mainly include maintaining cellular metabolism, regulating osmotic pressure and acid-base balance, and preserving cell stress response, etc. Daily potassium intake is about 100 millimoles, with 90% excreted through the kidneys and the remainder through the gastrointestinal tract. Common causes of hypokalemia include reduced intake, such as long-term inability to eat without timely potassium supplementation. Even though potassium intake decreases, the kidneys continue to excrete potassium, leading to potassium loss. The second cause is increased excretion, which includes losses through the gastrointestinal tract and the kidneys, both of which can lead to hypokalemia. The third cause is the movement of potassium from outside to inside the cells, which can occur during metabolic alkalosis or when glucose and insulin are administered, promoting the transfer of potassium ions into the cells, resulting in hypokalemia.

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Written by Wei Shi Liang

Intensive Care Unit

1min 1sec

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Causes and Clinical Manifestations of Hypokalemia

Hypokalemia refers to a condition where blood potassium levels are below 3.5mmol/L. The causes can be due to inadequate intake of potassium, such as prolonged inability to eat without sufficient intravenous supplementation of potassium. It can also result from excessive loss of potassium, through external losses such as vomiting and diarrhea, or through renal losses due to the excessive use of diuretics and certain hormonal imbalances. A third cause involves the shift of potassium into cells, such as during episodes of alkalemia and periodic paralysis. Clinically, mild to moderate hypokalemia is characterized by symptoms like muscle weakness, fatigue, cramps, intestinal obstruction, and some abnormalities in electrocardiograms, including the presence of U waves and flattened T waves. Severe hypokalemia can lead to life-threatening arrhythmias, such as ventricular tachycardia and ventricular fibrillation, which require immediate treatment.

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Written by Wei Shi Liang

Intensive Care Unit

45sec

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Why does hypokalemia cause alkalosis?

Hypokalemia can cause metabolic alkalosis because it leads to the intracellular movement of hydrogen ions. In hypokalemia, potassium shifts from the inside to the outside of the cell to compensate for the decreased serum potassium. As an exchange, hydrogen ions from the gastric fluid move into the cells, causing cellular alkalosis and intracellular acidosis. Additionally, due to potassium deficiency in the renal tubular epithelial cells, the potassium-sodium exchange decreases and the sodium-hydrogen exchange increases, leading to enhanced excretion of hydrogen ions and increased reabsorption of bicarbonate ions, resulting in hypokalemia-induced metabolic alkalosis, which needs to be promptly addressed clinically.