Carbohydrates are so called because they are compounds of carbon, hydrogen, and oxygen; the last two elements being present in the proportion in which they occur in water. The carbohydrates met with in the urine are chiefly glucose, levulose, lactose and inosite. They resemble one another in their chemical composition, in all containing six atoms of carbon or a multiple thereof. They also resemble one another in their chemical characteristics; being neutral in reaction, not prone to enter into combinations, and with the exception of inosite, they all possess a strong rotary power over polarized light.
The chief clinical interest with regard to the presence of carbo-hydrates in the urine at present belongs to grape sugar; some knowledge of the other carbohydrates met with in the urine is necessary for differential purposes in testing; as well in a few cases for their clinical significance, but since the latter are for