A 58-year-old man is given a glucose tolerance test. In the test, the plasma glucose concentration is increased and glucose reabsorption and excretion are measured. When the plasma glucose concentration is higher than occurs at transport maximum $\left(\mathrm{T}_{\mathrm{m}}\right)$, the

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[III B; Figure 5.5]. At concentrations greater than at the transport maximum $\left(\mathrm{T}_{\mathrm{m}}\right)$ for glucose, the carriers are saturated so that the reabsorption rate no longer matches the filtration rate. The difference is excreted in the urine. As the plasma glucose concentration increases, the excretion of glucose increases. When it is greater than the $\mathrm{T}_{\mathrm{m}}$, the renal vein glucose concentration will be less than the renal artery concentration because some glucose is being excreted in urine and therefore is not returned to the blood. The clearance of glucose is zero at concentrations lower than at $\mathrm{T}_{\mathrm{m}}$ (or lower than threshold) when all of the filtered glucose is reabsorbed but is greater than zero at concentrations greater than $\mathrm{T}_{\mathrm{m}}$.

A 58-Year-Old Man Is Given a Glucose Tolerance Test (Tm)\left(\mathrm{T}_{\mathrm{m}}\right)(Tm​) , the A) Clearance of Glucose Is Zero B) Excretion

A 58-Year-Old Man Is Given a Glucose Tolerance Test $\left(\mathrm{T}_{\mathrm{m}}\right)$ , the
A) Clearance of Glucose Is Zero
B) Excretion