Renal threshold.. Kidney's ability to retain sugar and return it to the blood after the nomination of harmful substances into the urine

Is the kidney's ability to retain sugar and return it to the blood after the nomination of harmful substances into the urine and this happens if the sugar 140/150/160 even 180 mg / dl However, if the concentration of sugar in the blood for 180 mg / Dl Begins to appear in the urine.