Question

Among the following, identify the non-protein nitrogen compounds of clinical importance in kidney diseases.

• A. Uric acid and Urea
• B. Urea and Creatinine
• C. Creatinine and Ammonia
• D. Uric acid and Ammonia

Hint:

Creatinine is a more reliable marker of GFR than urea because its production is less influenced by dietary protein intake, hepatic function, or hydration status.

Answer 1

The Correct Option is B

Step 1: Understanding the Concept:
Non-protein nitrogen (NPN) compounds are waste products of nitrogen metabolism that do not form proteins.
Because these compounds are primarily excreted by the kidneys, their accumulation in the blood serves as an index of renal function.

Step 2: Detailed Explanation:
Let us examine the primary NPN compounds evaluated in veterinary medicine:
Urea (Blood Urea Nitrogen - BUN): Generated in the liver through the urea cycle as a product of amino acid deamination and protein catabolism. It is filtered by the glomeruli and partially reabsorbed by the tubules.
Creatinine: Produced at a constant rate from the non-enzymatic degradation of creatine and phosphocreatine in skeletal muscle. It is filtered by the glomeruli and undergoes minimal tubular reabsorption or secretion in most domestic species.
Elevated blood levels of urea and creatinine (azotemia) are hallmark indicators of decreased glomerular filtration rate (GFR), making them the two most important NPN compounds for diagnosing and monitoring renal diseases.
Although uric acid is important in birds and reptiles, and ammonia is an indicator of hepatic dysfunction, urea and creatinine remain the primary clinical markers for mammalian kidney function.

Step 3: Final Answer:
The non-protein nitrogen compounds of key clinical importance in kidney diseases are Urea and Creatinine.