Tm for glucose is:
**Core Concept**
The question is asking about the transport maximum (Tm) for glucose, which is a measure of the maximum rate at which glucose can be transported across the renal tubular cells. This concept is related to glucose reabsorption in the kidneys and is a critical aspect of renal physiology.
**Why the Correct Answer is Right**
The transport maximum for glucose (Tm) is approximately 375 mg/min per 1.73 m^2 of body surface area. This value is the maximum amount of glucose that can be reabsorbed by the renal tubules per unit of time. The kidneys reabsorb glucose from the filtrate back into the bloodstream until the Tm is reached, after which excess glucose is excreted in the urine. The glucose reabsorption process is facilitated by the sodium-glucose cotransporter 2 (SGLT2) in the proximal convoluted tubule.
**Why Each Wrong Option is Incorrect**
* **Option A:** This option is not provided, but typically, a distractor might be a value that is too low or too high for the Tm for glucose.
* **Option B:** This option might be a value that is associated with another transport maximum, such as the Tm for amino acids or phosphate.
* **Option C:** This option might be a value that is associated with the maximum glucose concentration in the blood, rather than the transport maximum.
**Clinical Pearl / High-Yield Fact**
It's essential to remember that the Tm for glucose is a critical factor in the diagnosis of glucose intolerance and diabetes mellitus. An elevated glucose level in the blood can lead to an excessive amount of glucose being filtered by the kidneys, resulting in glycosuria. In patients with diabetes, the Tm for glucose is often elevated, allowing more glucose to be reabsorbed by the kidneys.
**Correct Answer: B. 370 mg/min per 1.73 m^2**