Body Fluid Balance (ECW/TBW Ratio)

Yes—in rats, a blood pressure drop triggered drinking, but not when one hormone signal was missing. A 2026 study in Physiological Reports explored what drives thirst. Researchers compared ordinary rats with rats missing a specific hormone receiver. That receiver lets cells respond to angiotensin II, a hormone involved in thirst and blood pressure. The study involved rats, not people. The rats missing this receiver had average blood pressure about 10 mmHg lower. Their heart rates were no different. Giving the hormone to ordinary rats increased drinking and blood pressure. Neither response happened in rats missing the receiver. A drug that lowered blood pressure also prompted ordinary rats to drink more. It did not prompt extra drinking in the altered rats. Yet both groups drank similar amounts after going without water overnight. They also responded similarly when salt levels in their blood rose. The missing signal blocked some triggers for thirst, but not all. For members tracking Body Fluid Balance (ECW/TBW Ratio), this offers context rather than a target. That ratio compares water outside cells with total body water. The study did not report changes in this ratio. It also did not test whether drinking more improves it. When comparing notes about Hydration, thirst and measured fluid balance are worth keeping distinct. Community logs could place thirst notes beside fluid-balance readings and drinking habits. Those notes may help describe personal patterns, without proving what caused them. What patterns have you noticed between your thirst, drinking habits, and fluid-balance readings?