Potassium Discussion Group

Hyperglycemia can cause potassium to leave cells due to

Increased osmolality in the ECV leads to water beign drawn out of cells, and K+ follows by solvent drag

Cell necrosis can cause potassium to leave cells due to

Elevation in other cellular components

What factors cause potassium to shift out of cells?

1. Hyperglycemia

2. Drugs

3. Acidosis

4. Cell necrosis

How does hyperglycemia cause potassium to shift out of cells?

Increased osmolality in the extracellular space draws the water out of cells, and K+ follows by solvent drag

How does cell necrosis cause potassium to shift out of cells?

The potassium normally contained within cells is now released into the ECV. This may be associated with elevations in other cellular components depending on which tissues are necrotic (liver enzymes, muscle enzymes such as creatinine kinase)

How does fasting cause potassium to shift out of cells?

Decreased basal insulin levels reduces insulin-stimulated intracellular K+ uptake. Insulin pushes K+ in the cells and low insulin results in higher K+ out of the cells

How does acidosis cause potassium to shift out of cells?

H+ ions move intracellularly in exchange for K+ ions

Why are diuretics used to treat high blood pressure?

They cause the body to lose salt and water, lowering blood volume and making it easier for blood to flow through arteries, which reduces blood pressure

Why would Hydrochlorothiazide (HCTZ) be an option to use as a diuretic?

It's effective at low doses, affordable, predictable, and safely lowers blood pressure without causing dramatic fluid loss

What are the common side effects of thiazide diuretics like HCTZ?

Low potassium (hypokalemia), dehydration, high blood sugar, and gout

How do thiazides cause low potassium (hypokalemia)?

• They block sodium reabsorption early in the kidney, so more sodium reaches areas where potassium gets excreted.

• They cause slight dehydration, triggering aldosterone, which also pushes the kidneys to dump more potassium.

How can you treat or prevent hypokalemia caused by diuretics?

• Give potassium supplements

• Or add a potassium-sparing diuretic (like spironolactone, triamterene, or amiloride).

Where do thiazide diuretics act on?

The distal convoluted tubule to decrease sodium reabsorption

What would furosemide be used for?

It is a diuretic that is reserved for acute conditions like increased edema with congestive heart failure or in cases of resistant edema like in nephrotic syndrome

What signs point to volume depletion?

Fast heart rate, low blood pressure (especially when standing), poor skin turgor, dry mucous membranes, high BUN:creatinine ratio

What does hyponatremia (low sodium) mean in volume depletion?

Loss of more salt than water, leading to an imbalance where the body has relatively too much water compared to salt

What causes the hypokalemia in vomiting and volume depletion?

Volume loss triggers aldosterone → Aldosterone makes kidneys save sodium but waste potassium → leads to low blood potassium levels

How should severe hypokalemia be treated?

Urgent IV potassium replacement; oral supplements if the patient can tolerate it later

What is the effect of aldosterone on sodium and potassium?

Increases sodium reabsorption and increases potassium excretion in the kidneys