Overview Nitrogen balance positive amino acid (AA) intake > excretion examples login to view 2 more bullets negative AA excretion > intake examples login to view 3 more bullets AA absorption in intestine proteins degraded by trypsin and pepsin enteropeptidase cleaves trypsinogen (inactive) to trypsin (active) absorbed as AA's across the gut lumen with specific transporter for similar AA's e.g., transporter for basic AA's, transporter for large neutral AA's deficiencies lack of absorption with pancreatitis due to ↓ in degradative enzyme production Hartnup disease login to view 3 more bullets AA absorption in kidney AA's that are filtered from the glomerulus can be actively reabsorbed in the proximal convoluted tubules with similar transporters as the gut deficiencies cystinuria login to view 8 more bullets