Final answer:
The determination of non-protein nitrogen has traditionally been used for synthesizing nitrogenous tissue constituents, diagnosing renal dysfunction, and analyzing proteins.
Step-by-step explanation:
The determination of non-protein nitrogen has traditionally been used for several purposes in biology.
Firstly, non-protein nitrogen is used for the synthesis of various nitrogen-containing tissue constituents like purines, pyrimidines, porphyrins, heme, epinephrine, nor epinephrine, melanin, and thyroxine.
Secondly, non-protein nitrogen estimation is important in diagnosing renal dysfunction. In case of renal failure, there is a significant increase in the concentration of non-protein nitrogenous substances (such as urea, uric acid, and creatinine) in the blood.
Lastly, in protein analysis, non-protein nitrogen plays a role in determining the concentration of drugs that are not binding to plasma proteins during drug discovery, therapeutic drug monitoring, and pharmacokinetic studies.