Final answer:
The statement is true. When the renal threshold is exceeded, a substance remains in the tubule fluid and is retained in the blood.
Step-by-step explanation:
The given statement is true. When the renal threshold has been exceeded, a substance remains in the tubule fluid and is retained in the blood.
When substances are filtered by the glomerulus and pass through the renal tubules, they can be reabsorbed back into the blood or excreted in the urine. However, if the amount of a particular substance in the filtrate exceeds the renal threshold, it cannot be completely reabsorbed and remains in the tubule fluid. This leads to the retention of the substance in the blood.
For example, the renal threshold for glucose is around 180-200 mg/dL. If the blood glucose concentration exceeds this threshold, the excess glucose cannot be completely reabsorbed in the renal tubules and is excreted in the urine, resulting in a condition called glucosuria.