QS Study

TmG Value

Definition: This is the maximum rate at which the glucose is reabsorbed per minute in the proximal convoluted tubules of the kidney is called TmG.

Normal value: 350 mg / min (Male) and 300 mg/min (Female).

The amount of glucose reabsorbed by the kidneys is equivalent to the amount entering the filtration system. The reabsorption increases with increase in glucose concentration up to approximately 11 m mol/L (198 mg/dL). At this threshold, the system becomes saturated and the maximal re-absorption rate, the glucose transport maximum (TmG), is reached. No more glucose can be absorbed, and the kidneys begin excreting it in the urine, the beginning of glycosuria. The TmG varies among individuals but it has an average value of approximately 375 mg/min for healthy subjects.

Fig: TmG Value

Importance: If the rate is above this value, then excess glucose is not reabsorbed but excreted out through urine.

Cause: This limitation is due to saturation of specific transport system.

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