Hypernatremia is defined as an abnormally high level of sodium circulating in the blood. In the context of Chronic Kidney Disease (CKD), this condition is most frequently a marker of severe "free water" dehydration. While the kidneys normally regulate sodium balance precisely, a cat with CKD loses the ability to concentrate urine, excreting large volumes of water. If the cat cannot drink enough to replace this lost water, the concentration of sodium in the blood rises effectively because the liquid volume has dropped. This state is dangerous because sodium attracts water; high levels in the blood pull fluid out of the brain cells, causing them to shrink, which can lead to neurological signs like confusion, weakness, or seizures. Furthermore, excessive sodium is a primary driver of Systemic Hypertension (high blood pressure). The body retains fluid to dilute the salt, increasing blood volume and pressure, which hammers the delicate filter units of the kidney. Consequently, a core pillar of CKD nutrition is a sodium-restricted diet to prevent this vicious cycle of high pressure and further renal damage.
Disclaimer: This content is for educational purposes only and does not constitute veterinary medical advice. Always consult with your primary care veterinarian or a veterinary internal medicine specialist regarding your cat’s specific condition.