Your veterinarian may refer to high levels of blood nitrogen in your cat as azotemia or uremia. Both are serious symptoms of underlying conditions only a veterinary professional is qualified to treat. If you suspect your cat has excess nitrogenous waste in her blood, schedule an appointment with a veterinarian as soon as possible. 

Several compounds in your cat's blood may contain nitrogen, such as creatinine, urea, and other byproducts of protein digestion. Levels of nitrogen-containing substances in the blood that are too high may indicate excessive dietary intake of protein, dehydration, or abnormal kidney function. 

Since blood circulates through and delivers nutrients to all parts of your cat's body, high levels of blood nitrogen can affect many systems and lead to some seemingly unrelated symptoms. Signs your cat may be suffering from azotemia or uremia include:

If you suspect your cat may be suffering from azotemia or uremia, seek veterinary attention immediately. These symptoms could be indicative of acute renal failure or a serious condition such as chronic kidney disease. 

The most common cause of high levels of blood nitrogen in cats is abnormal kidney function. If the kidneys are unable to filter waste products from the urine, waste will be resorbed back into the bloodstream. The kidneys may also fail to produce hormones necessary for nitrogen excretion, leading to the buildup of these products in the blood.

A diet that is too high in protein or the overproduction of nitrogen-containing substances can also elevate levels of blood nitrogen in cats. Dehydration can cause nitrogenous waste products to concentrate in the blood, artificially elevating blood nitrogen. Symptoms of chronic renal disease or diabetes, such as excess urination, excessive thirst, or rapid weight loss can also lead to elevated nitrogen in the blood.

Diagnosis of high levels of blood nitrogen will begin with a thorough physical examination of your cat, including the collection of all relevant medical history. Urine and blood samples will be collected by your veterinarian in order to perform relevant tests, such as a urinalysis, a complete blood count, and a chemistry profile. These tests will show whether nitrogenous waste is being excreted efficiently by the kidneys. It can also show what kind of nitrogen is present in the blood so that your veterinarian can determine the cause of the azotemia or uremia. 

In addition to confirming the presence of nitrogen in your cat's blood, your veterinarian will determine the cause of this buildup. Imaging such as x-rays and ultrasonography, urine cultures and tissue biopsies may be performed in to rule out chronic kidney disease or acute renal failure. The specific gravity, or concentration of particles, in your cat's urine may be measured to determine whether dehydration or excessive urination (polyuria) are contributing to the concentration of waste products in your cat's blood.

Your veterinarian will target the cause of high nitrogen levels in your cat’s blood when determining her course of treatment. For end-stage chronic kidney disease, your veterinarian may recommend dialysis or a kidney transplant. Alternatively, lifestyle modifications may be recommended to ease pain and symptoms of kidney disease, including the discomfort that results from high levels of nitrogen in the blood. 

For acute kidney disease, your veterinarian may administer rehydration fluids or place a temporary feeding tube. A catheter may be placed to promote the excretion of nitrogenous waste as urea in the urine. Prompt treatment of acute renal failure may restore some or all kidney function.

Your cat's prognosis will also vary depending on the cause of her azotemia or uremia. Cats with high levels of blood nitrogen secondary to dehydration, for example, can expect a full recovery. Cats newly diagnosed with late-stage chronic kidney disease or acute renal failure will require aggressive treatment, lifestyle management, and ongoing veterinary supervision to prevent relapse. 

Cats diagnosed with chronic kidney disease or acute renal failure will require intensive management throughout life. Your veterinarian may prescribe changes to your cat's diet, limiting fluid intake, medication, and ongoing monitoring of urine output. It is recommended cats in early stages of kidney disease follow-up with a veterinarian two or three times per year without symptoms. Cats in the late stages of kidney disease should be examined by a veterinarian every one to two months.