END PRODUCTS OF NITROGEN METABOLISM AND DISORDERS OF UREA SYNTHESIS AND EXCRETION: BIOCHEMICAL MECHANISMS, CLINICAL MANIFESTATIONS, AND MODERN PERSPECTIVES
Abstract
Nitrogen metabolism is a fundamental component of human physiology, ensuring the utilization of amino acids for protein synthesis while facilitating the safe elimination of excess nitrogen. The principal end products of nitrogen metabolism include urea, ammonia, uric acid, and creatinine. Among these compounds, urea serves as the primary route for nitrogen disposal in mammals through the hepatic urea cycle. Efficient urea synthesis and renal excretion are essential for maintaining nitrogen balance and preventing toxic accumulation of ammonia. Disorders affecting urea synthesis or excretion may result in hyperammonemia, hepatic encephalopathy, metabolic disturbances, and life-threatening neurological complications. Inherited urea cycle disorders and acquired liver or kidney diseases represent major causes of impaired nitrogen elimination. Recent advances in molecular genetics, metabolomics, and targeted therapies have improved understanding, diagnosis, and management of these conditions. This review discusses the biochemical basis of nitrogen metabolism, physiological roles of its end products, mechanisms of urea synthesis, disorders of urea production and excretion, and current therapeutic approaches.
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