Pathology of the urinary system

urea

 is produced in the liver from nitrogenous byproducts of protein metabolism (ammonia); 

  - 

creatinine

 is a normal byproduct of muscle metabolism (a degradation product of 

phosphocreatine, which provides energy for muscle contraction); 

---

 

 

3

 

  - 

blood urea nitrogen (BUN) and creatinine tend to be produced at a constant rate in the body 

and are also filtered and excreted in the urine at a relatively constant rate → abnormal 

retention in blood implies reduced glomerular filtration rate (GFR) and thus renal disease. 

 

   ∙ 

azotemia

 =  a biochemical abnormality referring to elevation of urea and creatinine in the blood,

 

mostly due to decreased GFR (without clinical signs of renal failure). 

 

   ∙