The primary catabolic end product of protein, non-protein nitrogen and purines depends upon a reptile’s natural environment. Terrestrial reptiles excrete [[Uric acid|uric acid]] as the primary nitrogenous waste product (i.e. they are uricotelic). [[Uric acid|Uric acid]] is synthesised in the liver and excreted by renal tubular secretion. The blood level is therefore largely independent of urine flow rate (and is therefore not a sensitive indicator of dehydration in reptiles or birds). Both animal and environmental factors influence [[Uric acid|uric acid]] levels. The normal blood [[Uric acid|uric acid]] value for most reptiles is 0 to 600 µmol/l. | The primary catabolic end product of protein, non-protein nitrogen and purines depends upon a reptile’s natural environment. Terrestrial reptiles excrete [[Uric acid|uric acid]] as the primary nitrogenous waste product (i.e. they are uricotelic). [[Uric acid|Uric acid]] is synthesised in the liver and excreted by renal tubular secretion. The blood level is therefore largely independent of urine flow rate (and is therefore not a sensitive indicator of dehydration in reptiles or birds). Both animal and environmental factors influence [[Uric acid|uric acid]] levels. The normal blood [[Uric acid|uric acid]] value for most reptiles is 0 to 600 µmol/l. |