The kidneys are part of the urinary system and perform many different functions for the body. They include filtration and elimination of metabolic wastes, regulation of of water and electrolyte balance and conservation of nutrients such as glucose and amino acids.

In this section we will cover:

  • Renal physiology: How the kidney eliminates nitrogenous waste, resorbs filtered substances (glucose, electrolytes, amino acids) preventing their loss, maintains water homeostasis (creation of a hypertonic medulla), and modulates acid-base status.
  • Types of renal disease: Acute renal injury and chronic renal disease.
  • Azotemia: The different types of azotemia (prerenal, renal and postrenal azotemia) and how to distinguish between them.
  • Laboratory indicators of renal disease: These include markers of glomerular filtration rate (GFR), such as urea nitrogen and creatinine. A urinalysis is an essential part of assessment of renal function as well. Since the kidney affects other test results, including proteins (particularly albumin) and electrolytes and minerals, these test results should be interpreted along with changes in more direct renal tests indicating renal dysfunction.