Renal Panel

A renal panel is a group of tests that may be performed together to evaluate kidney (renal) function. The tests measure levels of various substances, including several minerals, electrolytes, proteins, and glucose (sugar), in the blood to determine the current health of your kidneys.

The kidneys are a pair of bean-shaped organs located at the bottom of the ribcage to the right and left of the spine. They are part of the urinary tract and perform a few essential roles and functions within the body.

• Within the kidneys are about a million tiny blood filtering units called nephrons. In each nephron, blood is continually filtered through a cluster of looping blood vessels, called a glomerulus, which allows the passage of water and small molecules but retains blood cells, proteins such as albumin, and larger molecules.
• Attached to each glomerulus are tubes (tubules) that have a number of sections that collect the fluid and molecules that pass through the glomerulus, reabsorb what can be re-used by the body, add other molecules through a process called secretion and, finally, adjust the amount of water that is eventually eliminated along with the waste as urine.
• Besides eliminating wastes and helping to regulate the amount of water in the body, these activities allow the kidneys to maintain normal chemical balance in the body. Among the important substances the kidneys help to regulate are sodium, potassium, chloride, bicarbonate, calcium, phosphorus, and magnesium. The right balance of these substances is critical. When the kidneys are not working properly, the concentrations of these substances in the blood may be abnormal and waste products and fluid may build up to dangerous levels in the blood, creating a life-threatening situation.
• Kidneys also have a number of other miscellaneous roles in maintaining a healthy body, including the production of a hormone that stimulates red blood cell production (called erythropoietin), production of a hormone that helps maintain a normal blood pressure (called renin), and turning one form of vitamin D into a more active form, which enhances calcium absorption.

If the kidneys are not functioning properly, waste products can accumulate in the blood and fluid levels can increase to dangerous volumes, causing damage to the body or a potentially life-threatening situation. Numerous conditions and diseases can result in damage to the kidneys. The most common causes of and main risk factors for kidney disease are diabetes and hypertension. For more on the types and causes, see the article on Kidney Disease.

The individual tests included in a renal panel can vary by laboratory, but the tests typically performed include:

Electrolytes – electrically charged chemicals that are vital to normal body processes, such as nerve and muscle function; among other things, they help regulate the amount of fluid in the body and maintain the acid-base balance. Electrolytes include:

• Sodium
• Potassium
• Chloride
• Bicarbonate (Total CO₂)

Minerals

• Phosphorus – a mineral that is vital for energy production, muscle and nerve function, and bone growth; it also plays an important role as a buffer, helping to maintain the body's acid-base balance.
• Calcium – one of the most important minerals in the body; it essential for the proper functioning of muscles, nerves, and the heart and is required in blood clotting and in the formation of bones.

Protein

• Albumin – a protein that makes up about 60% of protein in the blood and has many roles such as keeping fluid from leaking out of blood vessels and transporting hormones, vitamins, drugs, and ions like calcium throughout the body.

Waste products

• Urea/Blood Urea Nitrogen (BUN) – urea is a nitrogen-containing waste product that forms from the metabolism of protein; it is released by the liver into the blood and is carried to the kidneys, where it is filtered out of the blood and eliminated in the urine.
• Creatinine – another waste product that is produced by the body's muscles; almost all creatinine is eliminated by the kidneys.

Energy Source

• Glucose – supplies energy for the body; a steady amount must be available for use, and a relatively constant level of glucose must be maintained in the blood.

Three calculated values may also be reported with a renal panel:

• Urea (BUN)/Creatinine Ratio – a comparison of urea (nitrogen) to creatinine content in the blood
• Estimated Glomerular Filtration Rate (eGFR) – a calculated estimate of the actual glomerular filtration rate (GFR, the amount of blood filtered by the glomeruli in the kidneys per minute) derived from creatinine levels in the blood; the formula takes into account the person's age, gender, race, and sometimes height and weight.
• Anion Gap – anion gap (AG or AGAP) is a value calculated using the results of an electrolyte panel. It evaluates the difference between measured and unmeasured electrical particles (ions or electrolytes) in the fluid portion of the blood.