renal threshold

Indeed, the most common reason for the glucose renal threshold ever being exceeded is diabetes.

But at blood concentrations above the renal threshold sugar starts appearing in the urine.

Many tests of kidney function amount to measures of renal thresholds for various substances.

This point is called the renal threshold of glucose (RTG).

They are excreted by the kidneys in a short time due to their low molar mass (which is below the renal threshold).

Indications for home monitoring of blood glucose in these patients are a raised glycosylated haemoglobin or a low renal threshold.

Renal thresholds vary by substance - the low potency poison urea, for instance, is removed at much lower concentrations than glucose.

Taken together, the collection of a kidney's renal thresholds essentially define much of its function in renal physiology.

In physiology, the renal threshold is the concentration of a substance dissolved in the blood above which the kidneys begin to remove it into the urine.

In properly functioning kidneys, glucose does not appear in urine until the renal threshold for glucose has been exceeded.

At this point, which is called the renal threshold, the excess glucose spills into the urine (glycosuria), where it can be seen in urine glucose testing.

Urine analysis will reveal significant levels of ketone bodies (which have exceeded their renal threshold blood levels to appear in the urine, often before other overt symptoms).

Urine glucose testing strips have a negative result until the renal threshold of 10 mmol/L or 180 mg/dL is reached or exceeded for a period of time.

This results in an increase in plasma concentration of fructose, eventually exceeding the renal threshold for fructose reabsorption resulting in the appearance of fructose in the urine.

Although the body's maximal store of vitamin C is largely determined by the renal threshold for blood, there are many tissues that maintain vitamin C concentrations far higher than in blood.

When the renal threshold of a substance is exceeded, reabsorption of the substance by the proximal renal tubuli is incomplete; consequently, part of the substance remains in the urine.

Molecules smaller than the renal threshold (60-70 kDa) are readily excreted in the urine while the larger ones are metabolized by plasma α-amylase before the degradation products are renally excreted.

It is true that home blood testing provides more accurate information than that available from urine tests, especially in patients with an abnormal renal threshold, and that it also provides information about everyday fluctuations.

The time-honoured method has been by urine testing, but with the renal threshold in the not so elderly being of the order of 10 mmol/1 glycosuria is only going to occur when the blood glucose is in double figures.

While urine testing remains the single most useful screening test for diabetes and the adequacy of its management, blood testing in addition provides definitive information and avoids the pitfall of a high renal threshold not uncommon in older patients, or the problem of not having a urine specimen immediately available.

Renal thresholds vary by species and by physiological condition; thus an animal may have different renal thresholds while hibernating, Renal thresholds can also be altered by many drugs, and may change in characteristic ways during certain illnesses.