The hormone that primarily causes hypokalemia, or low potassium levels in the blood, is aldosterone.
How Aldosterone Leads to Hypokalemia
Aldosterone is a hormone produced by the adrenal glands. Its primary function is to regulate sodium and potassium levels in the body. Specifically, aldosterone acts on the kidneys to:
- Increase Sodium Reabsorption: Aldosterone promotes the reabsorption of sodium back into the bloodstream.
- Increase Potassium Excretion: Simultaneously, it encourages the kidneys to excrete potassium into the urine.
When aldosterone is produced in excess, a condition known as hyperaldosteronism, it leads to:
- Increased Potassium Loss: Due to the increased excretion of potassium by the kidneys, excessive amounts are lost from the body.
- Hypokalemia Development: This loss of potassium results in low blood potassium levels or hypokalemia.
Conditions Associated with Excess Aldosterone
According to the provided reference from the Merck Manual, conditions such as Cushing syndrome can cause the adrenal glands to overproduce aldosterone, leading to significant potassium loss and resulting in hypokalemia.
Other Factors Contributing to Hypokalemia
While excess aldosterone is a significant cause of hypokalemia, other factors can also contribute to low potassium levels:
- Medications: Certain diuretics ("water pills") can increase potassium excretion by the kidneys.
- Gastrointestinal Loss: Severe vomiting or diarrhea can deplete potassium from the body.
- Dietary Deficiency: Although less common, a diet extremely low in potassium can lead to hypokalemia.
Summary
| Hormone | Effect on Potassium | Resulting Condition |
|---|---|---|
| Aldosterone | Increases potassium excretion | Hypokalemia |
In conclusion, while other factors can contribute to low potassium levels, aldosterone is the hormone most directly responsible for causing hypokalemia by increasing potassium excretion through the kidneys.
