For glucosuria to occur, which of the following must also be present?

• A. Uremia
• B. Hyperglycemia
• C. Ketonemia
• D. Azoturia

Answer: (B)

Glucosuria happens when glucose spills into the urine because the kidneys can’t reabsorb it all. The proximal tubules reclaim filtered glucose up to a limit called the renal threshold. When blood glucose rises above that threshold, the reabsorption capacity is exceeded and glucose appears in the urine. So, a necessary condition for glucosuria to occur is hyperglycemia.

If blood glucose is normal, glucose is efficiently reabsorbed and won’t be present in the urine, even if the kidneys are otherwise functioning. This is commonly seen with diabetes mellitus or other states that raise blood glucose. Other conditions listed, such as uremia, ketonemia, or azoturia, don’t have to be present for glucosuria to occur and aren’t the trigger for glucose appearing in the urine.