What is meant by surpassing the renal threshold?

Renal threshold refers to the plasma concentration at which a substance is filtered out of the blood and excreted in the urine. Surpassing the renal threshold means that the plasma concentration of a particular substance has exceeded the threshold level and the substance starts to appear in the urine.

When the plasma concentration of a substance is below the renal threshold, the substance is reabsorbed completely by the renal tubules back into the bloodstream. However, when the plasma concentration surpasses the renal threshold, the reabsorption capacity of the renal tubules gets overwhelmed and the substance starts to be excreted in the urine.

Surpassing the renal threshold is important for maintaining the body's homeostasis. It ensures that excess substances, such as waste products or drugs, are eliminated from the body through urine to prevent their accumulation in the bloodstream. The renal threshold can vary for different substances, and it can also be affected by factors such as diet, hydration status, and kidney function.