What does blood potassium mean

Blood potassium refers to the potassium content in the blood, because the potassium in food is generally absorbed by the intestines in a short time, and potassium ions can maintain the dynamic balance of the blood and the physiological activities of cells. It is very important for acid-base balance and protein metabolism. The range of blood potassium is related to neuromuscular reflexes, and we should understand that changes in blood potassium concentration are related to changes in function.

The potassium in the human body mainly comes from food. More than 90% of the potassium in food is absorbed in the intestines in a short period of time, and 90% of the potassium absorbed into the blood is excreted from the kidneys within 4 hours. Most potassium ions (98%) are present inside cells, and a small amount is present in the extracellular fluid at a constant concentration. The average K+ content in tissue cells is 150mmol/L, the K+ content in red blood cells is about 105mmol/L, and the K+ content in serum is about 4-5mmol/L. Potassium ions in the body are constantly exchanged between cells and body fluids to maintain a dynamic balance. Potassium is the main cation that maintains cell physiological activities. It plays an important role in maintaining the body's normal osmotic pressure and acid-base balance, participating in sugar and protein metabolism, and ensuring the normal function of nerves and muscles.

Normal range

Flame photometer method: 3.5～5.3mmol/L (3.5～5.3mEq/L).

Ion selective electrodeionization method: 3.9～5.3mmol/L (3.9～5.3mEq/L).

Enzyme kinetic method: 3.5～5.1mmol/L (3.5～5.1mEq/L).

Clinical significance

Hypokalemia

① Reduced intake: long-term fasting, anorexia, and eating less.

② Potassium moves into cells: insulin therapy, alkali poisoning, periodic paralysis (hypokalemic type), etc.

③ Increased potassium excretion in urine:

A. Increased secretion of mineralocorticoids: primary aldosteronism, 17α-hydroxylase deficiency, Cushing's syndrome, ectopic ACTH tumor, Bartter syndrome (juxtaglomerular hyperplasia syndrome with hypoaldosteronism and hypokalemic alkali poisoning), secondary aldosteronism (malignant hypertension, renovascular hypertension), juxtaglomerular cell tumor, large amounts of oral licorice, etc.

B. Increased distal tubular flow: diuretics (excretion of potassium), potassium-losing nephritis.

C. Renal tubular acidosis.

D. Fanconi syndrome.

④ Increased loss of potassium from the digestive tract: vomiting, diarrhea, colon cancer, choriocarcinoma, Zollinger-Ellison syndrome (Zollinger-Ellison syndrome pancreatic ulcer), WDHA syndrome (watery diarrhea and hypokalemia with islet cell adenoma syndrome), taking laxatives, etc.

⑤ Profuse sweating.

Hyperkalemia

① Excessive potassium supplementation: excessive oral (especially when urine volume is reduced due to renal insufficiency) or intravenous potassium supplementation.

② Potassium moves outside the cells: pseudohyperkalemia, acidosis, insulin deficiency, tissue necrosis, use of large doses of digitalis, periodic paralysis (hyperkalemic type), use of succinylcholine, etc.

③ Decreased urinary potassium excretion: acute or chronic renal failure or decreased extracellular fluid volume, etc.

④ Reduced activity of corticosteroid hormones: Addison's disease, hypofunction of the renin-angiotensin-aldosterone system, pseudohypoaldosteronism, drugs (spironolactone), etc.