Amino acids serve not merely as structural building blocks for macromolecular protein synthesis, but as critical metabolic intermediates, signaling ligands, and direct precursors for neuroactive amines and cellular metabolites. A disruption in their delicate stoichiometric equilibrium, commonly termed an amino acid imbalance, can trigger profound metabolic dysregulation, impaired protein synthesis, neurochemical anomalies, and homeostatic failure across multiple physiological systems. Understanding the pathways through which disparate amino acid profiles influence systemic physiology is essential for clinical diagnostics, nutritional science, and metabolic medicine.
Amino Acid Imbalance
1. Concise Definition
An amino acid imbalance is defined biochemically and nutritionally as an alteration in the relative proportions of circulating or intracellular amino acids such that the physiological ratio required for optimal proteostasis, metabolic signaling, and tissue maintenance is significantly disrupted. Unlike simple quantitative malnutrition, an imbalance occurs when one or more essential or non-essential amino acids are present in disproportionately high or low concentrations relative to the remainder of the pool, thereby impairing biological processes even when total nitrogen intake appears sufficient.
In metabolic pathology, this condition manifests when competitive dynamics for cellular transport systems, enzymatic degradation pathways, and tRNA aminoacylation cascades become asymmetrical. The consequences range from immediate reductions in voluntary feed or food intake and blunted growth rates to catastrophic neurotoxic syndromes and systemic multi-organ dysfunction.
2. Etymology & Linguistic Origin
The term is a compound construction combining biochemical nomenclature with physiological terminology. The root word amino derives via the German Amino- from ammonia, which traces etymologically to the Latin sal ammoniacus (salt of Ammon), named after the Temple of Ammon in ancient Libya near which ammonium salts were historically harvested. The noun acid originates from the Latin acidus, signifying sharp, sour, or tart, denoting compounds capable of donating protons or accepting electron pairs.
The constituent imbalance entered the English lexicon in the late nineteenth century, derived from the prefix in- (expressing negation or privation) compounded with the Old French balance, which stems from Late Latin bilanx (possessing two scale pans, from bi- [two] and lanx [plate or scale]). The precise phrase “amino acid imbalance” entered the modern scientific lexicon during the early to mid-twentieth century through pioneering investigations in mammalian nutrition, spearheaded by researchers seeking to explain why diets containing disproportionate mixtures of pure amino acids induced acute growth failure and metabolic suppression that exceeded the deficits caused by simple single-nutrient omissions.
3. Pronunciation & Grammatical Form
Pronunciation: /əˈmiː.noʊ ˈæs.ɪd ɪmˈbæl.əns/ (American English) or /əˈmiː.nəʊ ˈæs.ɪd ɪmˈbæl.əns/ (British English).
Grammatical Form: Compound noun phrase. In scientific and clinical prose, it functions primarily as an uncountable abstract noun (e.g., “prolonged amino acid imbalance alters cerebral neurotransmission”), though it readily accepts countable pluralization when classifying discrete clinical or experimental phenomena (e.g., “specific amino acid imbalances observed in acute liver failure”). The adjectival form is rendered as “amino-acid-imbalanced” (e.g., “an amino-acid-imbalanced diet”).
4. Detailed Conceptual Explanation
To understand the biological ramifications of an amino acid imbalance, one must first appreciate the concept of the free amino acid pool. Unlike carbohydrates and lipids, which can be stored in large macro-reservoirs such as glycogen and adipose triacylglycerols, mammals possess no specialized, metabolically inert storage vehicle for excess amino acids. Functional proteins in skeletal muscle, viscera, and circulating plasma represent the sole bodily reservoir of amino acids, and drawing upon these reserves requires catabolic proteolysis, which inevitably compromises cellular structure and enzymatic function.
Consequently, systemic homeostasis relies upon maintaining an equilibrium between dietary ingestion, endogenously catalyzed de novo synthesis of non-essential amino acids, protein turnover, and irreversible catabolic elimination via transamination, deamination, and the urea cycle. When the proportionate stoichiometry of this free pool is skewed, several distinct physiological disruptions occur simultaneously:
First, transport competition at biological barriers becomes severely distorted. Neutral, basic, and acidic amino acids rely upon specialized, saturable membrane transporter systems to traverse intestinal epithelia, enterocytes, and the blood-brain barrier. For instance, the large neutral amino acid transporter 1 (LAT1, encoded by SLC7A5) facilitates the sodium-independent exchange of branched-chain amino acids, aromatic amino acids, and other neutral species into the central nervous system. Because these substrates compete for binding to the same transport pocket, an excessive elevation of one class—such as phenylalanine in hyperphenylalaninemia—competitively inhibits the cerebral uptake of tryptophan and tyrosine, depleting essential precursor pools for serotonin, dopamine, and norepinephrine synthesis.
Second, protein synthesis at the ribosomal level is strictly subject to the availability of the single most limiting amino acid. If an amino acid imbalance provides an excess of certain amino acids alongside a relative deficiency of another, transfer RNA (tRNA) uncharging occurs for the deficient species. Uncharged tRNAs directly bind to and activate the general control nonderepressible 2 (GCN2) kinase, which subsequently phosphorylates eukaryotic initiation factor 2 alpha (eIF2α). This phosphorylation event shuts down global cap-dependent translation while selectively upregulating the transcription factor ATF4, driving an integrated stress response that initiates catabolism, alters cellular survival pathways, and triggers behavioral anorexia via neurocircuitry in the anterior piriform cortex.
Third, amino acid imbalances interfere with downstream nutrient-sensing cascades, specifically the mechanistic target of rapamycin complex 1 (mTORC1) axis. Amino acids—particularly leucine, arginine, and S-adenosylmethionine (a downstream product of methionine)—are obligatory upstream activators of mTORC1 via the Rag GTPase machinery and the cytosolic sensors Sestrin2, CASTOR1, and SAMTOR. Disproportionate levels of circulating amino acids can uncouple anabolic signaling from real physiological nutritional status, promoting aberrant cellular growth, dysregulated autophagy, and impaired mitochondrial oxidative capacity.
5. Historical Development
The systematic study of amino acid balance originated in the early decades of the twentieth century. Between 1909 and 1924, Thomas Burr Osborne and Lafayette Mendel demonstrated through precise rodent feeding trials that dietary proteins are not nutritionally equivalent; proteins lacking specific amino acids (such as zein from maize, which lacks lysine and tryptophan) failed to sustain mammalian growth. This work laid the groundwork for William Cumming Rose in the 1930s, who definitively isolated and characterized threonine, thereby establishing the complete repertoire of indispensable (essential) amino acids for mammalian life.
During the 1950s and 1960s, Alfred E. Harper and colleagues at the University of Wisconsin established the classical theoretical framework distinguishing among dietary amino acid deficiencies, imbalances, antagonisms, and toxicities. Harper recognized that adding a quantity of amino acids lacking the second most limiting amino acid to a diet already marginal in that nutrient produced a precipitous decline in voluntary food intake and animal weight gain, an effect that could be completely rescued by providing a trace supplement of the single limiting amino acid.
In parallel, the clinical recognition of endogenous amino acid imbalances expanded rapidly. In 1934, the Norwegian physician Asbjørn Følling identified phenylketonuria (PKU), proving that an inherited defect in a single catabolic enzyme (phenylalanine hydroxylase) could precipitate a devastating systemic amino acid imbalance characterized by toxic hyperphenylalaninemia and severe cognitive impairment. The advent of automated ion-exchange column chromatography by Stanford Moore and William H. Stein in the late 1940s and 1950s revolutionized the field, permitting the precise, high-throughput quantification of individual amino acids in biological fluids and solidifying the discipline of clinical amino acid biochemistry.
6. Theoretical Foundations
The study of amino acid imbalance rests upon several classical biochemical and nutritional theories:
Liebig’s Law of the Minimum: Originally formulated for agricultural botany by Carl Sprengel and popularised by Justus von Liebig, this principle dictates that biological yield is regulated not by total resources available, but by the scarcest critical nutrient. In mammalian biochemistry, protein synthesis cannot proceed beyond the limit set by the least abundant aminoacyl-tRNA. Excess quantities of all other nineteen amino acids cannot substitute for the missing substrate; instead, they must be transaminated, oxidized, or converted into urea, imposing an energetic cost on the organism.
Harper’s Tripartite Metabolic Classification: Harper codified amino acid deviations into three categories based on biological behavior:
- Imbalance: Arises when the pattern of dietary amino acids is altered without changing the absolute concentration of the most limiting amino acid, resulting in depressed intake that is corrected solely by providing the limiting amino acid.
- Antagonism: Occurs between structurally homologous amino acids (such as leucine, isoleucine, and valine, or lysine and arginine) that share transport systems or degradative enzymes. Excess of one antagonist increases the metabolic requirement for the other, and symptoms are corrected specifically by adding the structurally analogous competitor.
- Toxicity: Involves the massive, pathological accumulation of a single amino acid (e.g., methionine), leading to cell-autonomous oxidative stress, enzymatic inactivation, and metabolic injury independent of other amino acid concentrations.
The Neurochemical Competition Hypothesis: Developed by John Fernstrom and Richard Wurtman in the early 1970s, this theory holds that the synthesis rate of monoaminergic neurotransmitters in the mammalian brain is directly coupled to the ratio of their precursor amino acids relative to competing large neutral amino acids (LNAAs) in circulating plasma. Because the LAT1 transporter at the blood-brain barrier is near saturation under normal physiological conditions, an imbalance in the plasma ratio of tryptophan to other LNAAs directly modulates central serotonin synthesis, linking systemic nutritional state to affective behavior, thermoregulation, and satiety.
7. Key Components, Types & Dimensions
Amino acid imbalances manifest across varied biochemical dimensions, reflecting divergent etiologies and physiological contexts:
- Dietary/Exogenous Imbalance: Induced by consuming foodstuffs or synthetic diets characterized by skewed amino acid profiles, such as cereal-heavy diets lacking lysine or maize-dominated diets lacking tryptophan, leading to downstream biochemical sequelae even when caloric intake is maintained.
- Metabolic Antagonism: Competitive interactions between structurally homologous amino acids, most prominently seen among the branched-chain amino acids (BCAAs: leucine, isoleucine, and valine), where excess leucine accelerates the clearance of isoleucine and valine via shared branched-chain alpha-keto acid dehydrogenase (BCKDH) complexes.
- Inborn Errors of Metabolism: Monogenic enzymatic deficiencies that prevent normal amino acid catabolism, such as Maple Syrup Urine Disease (MSUD), PKU, and homocystinuria, causing massive endogenous elevations of upstream metabolites alongside critical peripheral tissue deprivations of downstream products.
- Secondary Organ-Failure Imbalances: Pathological deviations resulting from parenchymal organ failure. In decompensated liver cirrhosis, impaired hepatic clearance of aromatic amino acids (phenylalanine, tyrosine, tryptophan) coupled with hyperinsulinemia-driven skeletal muscle uptake of BCAAs produces a marked inversion of the plasma BCAA-to-aromatic amino acid ratio (Fischer’s ratio).
- Critical Illness Hypercatabolism: Severe polytrauma, sepsis, and extensive thermal injury prompt profound skeletal muscle proteolysis, rapid glutamine and arginine consumption, and accelerated hepatic acute-phase protein synthesis, generating acute systemic amino acid imbalances characterized by systemic glutamine depletion and elevated circulating sulfur-containing metabolites.
8. Examples & Illustrative Cases
To contextualize these principles, several well-characterized clinical and experimental examples illustrate the tangible manifestations of amino acid imbalance:
Case 1: Fischer’s Ratio Inversion and Hepatic Encephalopathy. A 58-year-old patient with end-stage cirrhosis presents with lethargy, asterixis, and episodic confusion. Laboratory evaluation reveals elevated serum ammonia, but critically, plasma amino acid profiling demonstrates a Fischer’s ratio (molar ratio of [Leucine + Isoleucine + Valine] to [Phenylalanine + Tyrosine]) of 1.1, compared to the physiological baseline of 3.0 to 4.0. The marked reduction in circulating BCAAs relative to aromatic amino acids shifts LAT1-mediated transport across the blood-brain barrier decisively in favor of aromatic amino acids. The resulting influx of phenylalanine and tyrosine stimulates the synthesis of false neurotransmitters such as octopamine and phenylethanolamine, while inhibiting physiological dopaminergic transmission and accelerating neurotoxic glutamatergic signaling, precipitating hepatic encephalopathy.
Case 2: Leucine-Induced Antagonism in Experimental Diets. In nutritional biochemistry models, feeding animals a low-protein diet supplemented with 5% excess L-leucine induces profound growth retardation, progressive weight loss, and reduced feed efficiency within 48 hours. Leucine triggers the allosteric activation of hepatic BCKDH kinase phosphatase, leading to rapid dephosphorylation and activation of the rate-limiting BCKDH enzyme complex. Because BCKDH oxidizes the alpha-keto acids of all three branched-chain amino acids indiscriminately, the hyperactivity induced by excess leucine drives rapid co-oxidation and catabolic clearance of valine and isoleucine, precipitating acute tissue deficiencies of these two essential amino acids. The condition is rapidly normalized not by withdrawing leucine, but by supplementing small quantities of isoleucine and valine.
Case 3: Maternal Phenylketonuria Syndrome. A pregnant individual with classic PKU who fails to adhere to a strict phenylalanine-restricted diet maintains maternal blood phenylalanine concentrations above 1200 micromoles per liter. Phenylalanine is actively transferred across the placental syncytiotrophoblast by system L amino acid transporters, concentrating phenylalanine in fetal circulation up to twice the maternal level. This profound amino acid imbalance deprives the developing fetal brain of tyrosine, tryptophan, and other critical substrates, impairing embryonic neural crest migration and protein synthesis, resulting in microcephaly, congenital heart disease, and severe intellectual disability in the offspring, irrespective of the infant’s own genetic status.
9. Measurement & Assessment
Assessing and diagnosing amino acid imbalances requires quantitative, high-resolution analytical methodologies, as qualitative assessments fail to capture subtle stoichiometric deviations:
Ion-Exchange Chromatography (IEC): Historically considered the gold-standard reference method, post-column ninhydrin derivatization coupled with cation-exchange chromatography resolves more than forty physiological amino acids and related compounds in plasma, urine, and cerebrospinal fluid based on their charge properties and hydrophobic interactions.
Liquid Chromatography-Tandem Mass Spectrometry (LC-MS/MS): Contemporary clinical laboratories rely on electrospray ionization (ESI) LC-MS/MS, often employing stable isotope-labeled internal standards. This platform delivers picomolar sensitivity, high precision, and rapid turnaround times, making it indispensable for high-throughput newborn screening programs designed to identify inherited inborn errors of metabolism from dried blood spots within hours of birth.
Diagnostic Indices and Biomarker Ratios: Beyond absolute concentrations, diagnostic interpretation relies heavily upon relational ratios:
- Fischer’s Ratio: Measures the stoichiometric balance between BCAAs and aromatic amino acids, serving as an indicator of hepatic functional reserve and neurochemical vulnerability.
- Phenylalanine-to-Tyrosine Ratio (Phe/Tyr): A sensitive index used to evaluate the in vivo enzymatic activity of phenylalanine hydroxylase and monitor dietary control in PKU management.
- Methionine-to-Homocysteine Ratio: Used to pinpoint disruptions in one-carbon metabolism, remethylation, and transsulfuration pathways.
Sample Preparation and Pre-analytical Variables: Accurate measurement demands meticulous pre-analytical handling. Prolonged contact of plasma with erythrocytes leads to the enzymatic degradation of labile amino acids such as glutamine and asparagine, alongside the rapid artifactual release of taurine, aspartate, and glutamate from lysed cells. Consequently, specimens must be collected in heparin or EDTA tubes, maintained on ice, separated within 30 minutes, deproteinized (typically with sulfosalicylic acid), and frozen at -80 degrees Celsius.
10. Applications & Practical Significance
Understanding the physiological impacts of amino acid imbalances has direct, multi-disciplinary applications across clinical medicine, public health, and animal husbandry:
Clinical Nutrition and Total Parenteral Nutrition (TPN): In patients requiring long-term intravenous feeding due to intestinal failure, early synthetic amino acid formulations that lacked precise balance caused severe metabolic acidosis, hyperammonemia, and cholestatic liver injury. Modern parenteral formulations are engineered with balanced, crystalline L-amino acid solutions tailored to specific patient populations—such as pediatric formulas enriched with taurine, histidine, and cysteine, or renal failure formulas restricted in non-essential amino acids to minimize toxic nitrogenous waste generation.
Management of Inborn Errors of Metabolism: Medical nutrition therapy for disorders such as MSUD and PKU relies on using medical foods composed of free amino acid mixtures that are completely devoid of the offending amino acid (e.g., phenylalanine or leucine) but enriched in other essential amino acids to maintain overall proteostasis without triggering an imbalance-induced integrated stress response.
Oncology and Amino Acid Depletion Therapy: Certain neoplastic cells display strict metabolic dependencies on specific exogenous amino acids due to epigenetic silencing of synthetic enzymes (e.g., asparagine synthetase in acute lymphoblastic leukemia, or argininosuccinate synthetase in hepatocellular carcinoma). Administering therapeutic enzymes such as pegylated L-asparaginase or PEGylated arginine deiminase induces targeted systemic amino acid imbalances, starving cancer cells while largely sparing healthy tissues capable of de novo synthesis.
Agricultural Animal Formulation: In modern agronomy and livestock production, balancing dietary amino acids to match the “ideal protein concept” minimizes feed costs and substantially reduces environmental nitrogen excretion. Supplementing basal grain diets with synthetic crystalline L-lysine, DL-methionine, and L-threonine satisfies the animal’s exact physiological requirements without necessitating excessive crude protein intake, mitigating both intestinal disease and ammonia emissions.
11. Research & Empirical Evidence
Extensive empirical research spanning basic molecular biology to human clinical trials has documented the intracellular signaling and macroscopic phenotypes induced by amino acid imbalances:
Classic studies by Harper, Rogers, and Leung (1960s) demonstrated that feeding rats an imbalanced amino acid mixture caused an abrupt cessation of food consumption within two to three hours. Subsequent neurobiological studies by Dorothy Gietzen and colleagues revealed that the anterior piriform cortex serves as an essential chemosensory brain center for sensing amino acid deficiency. When uncharged tRNAs accumulate due to an imbalanced amino acid profile, GCN2 kinase phosphorylates eIF2α directly within piriform neurons, altering membrane excitability, inhibiting downstream orexigenic signaling, and prompting rapid behavioral aversion to the imbalanced food source.
In human clinical trials, research into the Branched-Chain Amino Acid Paradox has illuminated the complex relationship between circulating amino acid profiles and metabolic health. Large-scale metabolomic cohort studies led by Christopher Newgard and colleagues (2009) established that elevated circulating levels of BCAAs and their downstream acylcarnitines consistently predict the future development of type 2 diabetes and insulin resistance, independent of body mass index. Subsequent mechanistic work demonstrated that prolonged elevations in circulating BCAAs over-activate the mTORC1/S6K1 kinase signaling axis, causing serine phosphorylation of insulin receptor substrate 1 (IRS-1), which impairs insulin-mediated glucose disposal and contributes to peripheral insulin resistance.
12. Cultural & Cross-Cultural Considerations
The prevalence, risk factors, and presentation of dietary amino acid imbalances exhibit pronounced geographic, cultural, and socioeconomic variation:
In developing regions, food insecurity and dependence on single carbohydrate-dense staple crops lacking diverse protein sources can precipitate primary amino acid imbalances. For example, populations dependent almost entirely on cassava, plantains, or polished rice are vulnerable to protein-energy malnutrition syndromes such as kwashiorkor. While historically viewed merely as total protein deficit, the classic phenotypic features of kwashiorkor—including fatty liver, generalized edema, and hypoalbuminemia—are compounded by acute imbalances among sulfur amino acids (methionine and cysteine), which disrupts apolipoprotein synthesis and compromises cellular glutathione reserves.
Conversely, in high-income industrialized nations, dietary amino acid imbalances are increasingly driven by cultural trends toward ultra-processed foods or, alternately, unsupervised high-dose single-amino acid supplementation. The widespread consumption of isolated protein powders, mega-dose BCAA supplements for athletic performance, and restrictive elimination diets can expose individuals to unnatural amino acid stoichiometry, potentially straining renal glomerular filtration rates, altering hepatic enzyme induction, and disturbing central monoamine synthesis pathways.
13. Criticisms, Debates & Limitations
Despite foundational scientific advances, several controversies and diagnostic limitations persist regarding the clinical application of amino acid balance models:
Therapeutic Utility of BCAA Supplementation in Cirrhosis: While the biochemical logic underlying the Fischer ratio in hepatic encephalopathy is well validated, the clinical efficacy of correcting this imbalance using oral or intravenous BCAA-enriched formulas remains contested. Several systematic reviews and Cochrane meta-analyses have found that although BCAA supplementation can improve hepatic encephalopathy symptoms, it offers inconsistent improvements in overall patient survival, prompting ongoing debate regarding whether BCAA depletion is a primary driver or simply an epiphenomenon of end-stage liver failure.
Safety of High-Dose Single Amino Acid Supplementation: The commercial availability of concentrated individual amino acids (such as L-arginine, L-tryptophan, and L-glutamine) has outpaced human toxicology research. The historical tragedy of Eosinophilia-Myalgia Syndrome in 1989, linked to contaminated L-tryptophan supplements, highlighted how little was known regarding systemic immune responses to distorted circulating amino acid pools. Questions remain regarding long-term, supra-physiological consumption of isolated amino acids, particularly regarding vascular remodeling, renal tubular stress, and metabolic signaling.
Diagnostic Ambiguity of Static Plasma Measurements: Conventional diagnostic panels quantify static, fasting plasma concentrations, which represent less than two percent of total whole-body amino acid pools. These measurements often fail to reflect the dynamic intracellular fluxes, tissue-specific compartmentalization, or continuous metabolic turnover that occur in skeletal muscle, liver, and brain tissues. Critics argue that relying exclusively on peripheral plasma profiles without tracer kinetics or intracellular metabolomic monitoring may yield misleading conclusions regarding a patient’s functional metabolic state.
14. Related Terms & Distinctions
Differentiating an amino acid imbalance from related nutritional and metabolic states is vital for diagnostic and therapeutic clarity:
- Amino Acid Deficiency: The absolute lack or insufficient dietary intake of an essential amino acid below the minimum physiological threshold required for nitrogen balance. While an imbalance involves a distorted ratio among amino acids where total nitrogen intake may remain normal, a deficiency is a quantitative shortage of a specific nutrient.
- Amino Acid Toxicity: Pathological damage resulting from massive, isolated tissue accumulation of a single amino acid (most notably methionine or cysteine). Unlike an imbalance, toxicity cannot be corrected or ameliorated by supplementing other amino acids and often leads to structural tissue injury or direct cellular oxidative stress.
- Amino Acid Antagonism: A specific subclass of interaction wherein an excess of one amino acid increases the biological requirement for another structurally related amino acid that shares transport systems or degradation pathways (such as the antagonistic relationship between leucine, isoleucine, and valine).
- Aminoacidopathy: An inherited inborn error of metabolism characterized by a genetic enzyme or transporter defect that blocks the normal physiological degradation or transport of specific amino acids (e.g., PKU, albinism, alkaptonuria), leading to secondary endogenous amino acid imbalances.
- Protein-Energy Malnutrition (PEM): A broad clinical spectrum encompassing marasmus (caloric deprivation) and kwashiorkor (protein deprivation), representing a systemic macronutrient deficit, whereas an amino acid imbalance can emerge even in states of caloric and total nitrogen surfeit.
15. Summary / Key Takeaways
- Amino acid homeostasis depends upon maintaining a strict physiological stoichiometry across intracellular and circulating free amino acid pools, which lack a metabolically inert macromolecular storage reservoir.
- An amino acid imbalance alters the physiological ratios among amino acids, disrupting transport across saturable biological carriers (such as LAT1) and impairing ribosomal translation via GCN2 and mTORC1 signaling pathways.
- Imbalances stem from diverse etiologies, including poorly formulated diets, metabolic antagonism among structurally related substrates, inborn errors of metabolism, and parenchymal organ failure (e.g., cirrhosis).
- Measuring amino acid balance requires quantitative analytical platforms, primarily high-performance liquid chromatography and tandem mass spectrometry (LC-MS/MS), paired with specific biomarker ratios such as Fischer’s ratio.
- Correcting an imbalance requires restoring physiological proportionality, whether through targeted medical foods, balanced parenteral nutrition, or dietary supplementation designed to replenish the most limiting substrate.
Ultimately, amino acid imbalance illustrates the precision with which systemic physiology monitors and regulates biochemical resources. The biological response to disproportionate nutrient availability encompasses cellular nutrient sensing, competitive transporter dynamics, neuroendocrine feedback, and behavioral adaptations. A rigorous understanding of these pathways continues to inform clinical interventions, advanced nutritional support strategies, and targeted therapeutic approaches for metabolic disease.
References
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- Fischer, J. E., Funovics, J. M., Aguirre, A., James, J. H., Keane, J. M., Wesdorp, R. I., Yoshimura, N., & Westman, T. (1975). The role of plasma amino acids in hepatic encephalopathy. Surgery, 78(3), 276–290. https://pubmed.ncbi.nlm.nih.gov/1154096/
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