Functioning kidneys (paired organs in the abdomen) are necessary for body health in all warm blooded creatures. They are extremely complicated and do much more than make urine. They filter the blood of protein breakdown products (toxins), retain important electrolytes and regulate red blood cell production. They are also vitally important for maintaining hydration. The kidneys of a cat or dog with kidney insufficiency, will not be able to retain fluid requiring the pet to drink more water to help flush the blood of toxins. Noting that your cat or dog is drinking excessive amounts of water can be an indication that the kidneys are not functioning properly. It is important to know that once the cat or dog develops symptoms of kidney disease, or kidney insufficiency is found by way of blood tests, a significant amount of the kidney tissue has been depleted and cannot be regenerated. Important parameters in the blood will help your veterinarian to determine if there is kidney insufficiency or uremia. Creatinine is one of the more critical by products of protein breakdown and is usually found in small amounts when tested. An elevated creatinine level is a significant indicator of kidney dysfunction. A newer test, and a more sensitive one, is called SDMA (symmetrical dimethylarginine). However, only IDEXX laboratories currently have the test for SDMA, so it is not universally used. BUN (blood urea nitrogen) is another parameter of kidney function. It is not as important in assessing the kidneys as is Creatinine or SDMA because it is also influenced by diet. There are many other considerations when looking at the results of blood testing to evaluate the kidneys. Most are beyond the scope of this post, but one other bears mentioning: an electrolyte called phosphorus. When this product is elevated significantly in the blood, it’s an indicator (in my view) that the kidney function is near end stage. Hypertension is another consideration as increased blood pressure can damage the kidneys and vice versa, kidney disease can lead to hypertension. While testing blood pressure is relatively simple in humans, it can be quite challenging to get quality readings in the cat due to the fact they are often stressed when in a hospital setting. Chronic kidney disease can also lead to anemia (a lower than normal number of circulating red blood cells) and this condition can be another indication of how serious the problem is. Kidney disease is a chronic condition that is slowly progressive and not specifically treatable because the kidneys, once diminished, cannot regenerate. However, there are a multitude of modalities such as special diets, supplements, phosphorus binders, subcutaneous fluids and others that can slow the progression and make the patient feel better. It’s important to discuss your concerns with your veterinarian and digest as much information as possible so you can understand what is going on if kidney insufficiency has been diagnosed or you feel it is potentially a possibility with your pet. Here is an excellent source for more information: