What is hypovolemic thirst?

Hypovolemic thirst occurs when there is a significant drop in blood volume, which can be caused by factors such as bleeding, vomiting, or diarrhea. This decrease triggers a response in the body to maintain fluid balance by creating a strong urge to drink fluids.

Key mechanisms involved include:

1. Baroreceptors in the OVLT: These sensors detect decrease in blood pressure due to reduced blood volume.
2. Renin-Angiotensin System: The kidneys release renin, which activates angiotensin II from the lungs. Angiotensin II then acts on the OVLT to induce thirst.
3. Fluid and Salt Balance: Both types of thirst, osmotic and hypovolemic, involve fluid intake and regulation of salt levels in the body to maintain proper function.

Ultimately, this system ensures that when blood volume drops, the body responds appropriately by seeking out water and often salt, which helps retain the consumed water and restore proper blood pressure and volume levels 1 2.

For a comprehensive explanation, you might want to check out Andrew Huberman’s discussion on the Huberman Lab in the episode [Using Salt to Optimize Mental & Physical Performance].