It is much easier to predict the complications of CKD if we understand what alteration of the kidney function are observed as a result of the chronic kidney injury. Recall from your A&P course, what are the functions of the kidney?

The kidneys are vital organs that perform several important functions in the body. These include:

1. Filtration of Blood: The primary function of the kidneys is to filter out waste products and excess substances from the blood, which are then excreted as urine.

2. Regulation of Fluid and Electrolyte Balance: The kidneys help maintain the body's balance of water and various essential minerals, such as sodium, potassium, and calcium.

3. Acid-Base Homeostasis: The kidneys regulate the body's pH level by excreting hydrogen ions and reabsorbing bicarbonate from urine.

4. Blood Pressure Regulation: By controlling the volume of blood and the amount of sodium reabsorbed by the kidneys, they play a key role in regulating blood pressure.

5. Erythropoiesis Regulation: The kidneys produce and release erythropoietin, a hormone that stimulates the production of red blood cells in the bone marrow.

6. Metabolism of Vitamin D: The kidneys convert vitamin D into its active form, which is essential for the absorption of calcium and phosphate in the intestines.

7. Detoxification: The kidneys help detoxify the body by removing waste products and drugs from the bloodstream.

Understanding these functions can help predict the complications of Chronic Kidney Disease (CKD), as the disease often leads to a decrease or loss in these functions.