The Important Numbers
BUN
Blood urea nitrogen (better known as BUN) tests measure the amount of urea, one of the body’s waste products, in blood. Urea is produced when the liver is involved in protein metabolism. Kidneys are responsible for removing the waste product. The liver and the kidneys work together to balance normal levels of urea.
Dogs are referred to as uremic or suffering from uremia when urea, normally eliminated through urine, accumulate in their blood at toxic levels.
BUN coupled with creatinine levels help determine how well the kidneys are functioning. High levels indicate poor or failing kidneys.
With kidney disease, early detection is key in treatment of both acute and chronic cases. Blood tests measuring symmetrical dimethylarginine (SDMA) have been pivotal in early detection of kidney disease.
Creatinine
Creatinine is a waste product produced by muscles from the breakdown of a compound called creatine. Creatinine levels may temporarily increase due to dehydration, low blood volume, eating large amounts of meat or taking certain medications.
Creatinine is removed from the body by the kidneys, which filter almost all of it from the blood and release it through urine. When kidney function decreases beyond a certain point, an increase in blood creatinine concentration (hypercreatininemia) occurs, usually accompanied by increased urea concentration. Azotemia refers to an increases in either or both creatinine and/or urea.
Dehydration may increase creatinine levels. Levels may also increase through digestion of exogenous creatinine (some creatine in meat is converted to creatinine during cooking).
Phosporus
Phosphorus is also a structural component of DNA and RNA, the molecules that carry each cell’s genetic code. Vast quantities of phosphorous are located in bones and teeth, bonded with calcium. Calcium and phosphorus are often regarded together as the body is in harmony when the two are delicately balanced.
Hyperphosphatemia is an electrolyte disturbance in which abnormally elevated levels of phosphate are present in a dog's blood. Elevated levels can occur at any age but are often present in puppies and dogs with kidney disease.
Failing kidneys are no longer efficient at ridding excess phosphorus, which comes from certain digested proteins. The rise in phosphorus upsets the delicate balance between calcium and phosphorus and activates a regulatory hormonal cascade that attempts to re-establish control. Kidneys are responsible for regulating this control. Without proper function, calcium is drawn from bones, weakening them, to balance or reestablish homeostasis with higher phosphorus levels.
IRIS Staging
The International Renal Interest Society is a leader in veterinary nephrology and responsible for providing practicing veterinarians with evidence-based guidance for diagnosing, treating and managing kidney disease. IRIS works with both acute and chronic conditions, but our focus at CyCyTheAdventureDog.com is on chronic kidney disease (CKD). According to IRIS, protocol for determining the stage of CKD is: “Staging of chronic kidney disease (CKD) is undertaken following the diagnosis of CKD in order to facilitate appropriate treatment and monitoring of the patient. Staging is based initially on fasting blood creatinine, assessed on at least two occasions in the stable patient. The patient is then substaged based on proteinuria and systemic blood pressure.”
If you or someone you know is a pet parent caring for a pet with kidney disease, IRIS is provides information, handbooks and pocket guides for both acute and chronic cases, and have been pivotal in our learning.
Understanding Labs Resources
This chart by IDEXX laboratories is a great, easy guide to understanding labs. It was extremely helpful for us in learning what our numbers mean.
Cy’s Labs
