inDEPTH: Excess Nitrogen in the Body

With most Americans recently celebrating Thanksgiving by joining friends and family over a large, turkey-heavy celebratory meal, we take an inDEPTH look at how our bodies deal with excess nitrogen. 

Animals mostly excrete excess nitrogen as ammonia, urea, or uric acid, which is produced during protein metabolism. Ammonia is the direct waste produced as a byproduct of protein metabolism by all animals. But because of its toxicity, many animals convert ammonia into a less toxic form. The major excretory product in humans is urea, which is excreted in urine by the kidneys. 

Fun fact: birds and reptiles have evolved the ability to convert toxic ammonia into uric acid, which packs four nitrogens into each molecule, compared with two nitrogens in each human urea molecule. Not only is that a much more efficient means of excreting nitrogen, uric acid is a white crystal precipitate, which is why guano is white and makes such an excellent fertilizer.

Humans have many diseases caused by excess nitrogen. Later in this episode, we will talk with Dr. Julien Baruteau, from the Metabolic Medicine Department, Great Ormond Street Hospital for Children NHS Foundation Trust, in London, UK, about how his lab goes about modeling urea cycle disorders using patient cells. But first, we speak with Dr. Michael Pillinger (NYU Grossman School of Medicine, NY), about how gout flares result from an innate immune response against monosodium urate crystal deposits, and about his recent results from the PIVOTAL study, presented at the ACR Convergence 2022 meeting.  

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