Glucuronide tubular reabsorption

Preterm infants, especially those near the limits of viability (24 weeks gestation), have glomerular filtration rates approximately one-tenth that of a term newborn. Because of limitations on tubular reabsorption, they have increased urinary loss of filtered substances. Glucuronidation pathways appear after 20 weeks of gestation and so are limited in extremely premature infants. 

The process of reabsorption depends on the HpophiHc—hydrophiHc balance of the molecule. Charged and ioni2ed molecules are reabsorbed slowly or not at all. Reabsorption of acidic and basic metaboHtes is pH-dependent, an important property in detoxification processes in dmg poisoning. Both passive and active carrier-mediated mechanisms contribute to tubular dmg reabsorption. The process of active tubular secretion handles a number of organic anions and cations, including uric acid, histamine, and choline. Dmg metaboHtes such as glucuronides and organic acids such as penicillin are handled by this process. 

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