The hormone that most commonly causes hyponatremia (low sodium levels in the blood) is antidiuretic hormone (ADH), also known as vasopressin.
Here's a more detailed explanation:
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ADH and its Role: ADH's primary function is to regulate water balance in the body. It signals the kidneys to conserve water by reducing urine output.
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SIADH and Hyponatremia: The Syndrome of Inappropriate Antidiuretic Hormone (SIADH) occurs when the body produces too much ADH. This excess ADH causes the kidneys to retain excessive amounts of water. This water retention dilutes the sodium concentration in the blood, leading to hyponatremia.
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How SIADH Leads to Hyponatremia:
- Increased ADH: The body produces more ADH than necessary.
- Water Retention: The kidneys reabsorb more water, reducing urine output and increasing the body's water volume.
- Sodium Dilution: The excess water dilutes the sodium concentration in the blood.
- Hyponatremia: This dilution results in a lower-than-normal sodium level in the blood, which is defined as hyponatremia.
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Conditions That Can Cause SIADH: Several conditions can trigger SIADH, including:
- Certain cancers
- Lung diseases
- Central nervous system disorders
- Certain medications
Therefore, while other factors can contribute to hyponatremia, excessive production of antidiuretic hormone (ADH), particularly in the context of SIADH, is a major cause.
