What is the renal threshold range for plasma concentration where active transport stops?

The renal threshold range for plasma concentration where active transport stops is indeed around 160-180 mg/dl. This threshold is significant in the context of renal physiology, particularly in the treatment of substances like glucose in the blood. Active transport refers to the movement of substances across the renal tubule cells, allowing for reabsorption into the bloodstream.

When the concentration of a substance in the plasma exceeds the renal threshold, the renal tubules are unable to reabsorb all of it, resulting in an increase of that substance in the urine. For glucose, this threshold is approximately 180 mg/dl. Therefore, at concentrations above this range, glucose will begin to appear in the urine, a phenomenon observed in conditions such as uncontrolled diabetes mellitus.

Understanding the renal threshold helps in diagnosing and monitoring various clinical conditions by linking plasma levels of certain substances with their excretion in urine. The range of 160-180 mg/dl is critical because it marks the transition from active reabsorption to passive excretion, which has important implications for assessing kidney function and managing metabolic disorders.