Carbohydrate metabolism disorders Notes
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NOTES NOTES CARBOHYDRATE METABOLISM DISORDERS GENERALLY, WHAT ARE THEY? PATHOLOGY & CAUSES ▪ Inherited disorders of carbohydrate metabolism (fructose, glucose, galactose) ▪ Determined by exposure to external triggers (e.g. dietary factors) ▪ Disruption in certain metabolic pathways → accumulation of byproducts → systemic alterations, organ failures SIGNS & SYMPTOMS ▪ See individual disorders DIAGNOSIS LAB RESULTS ▪ Enzymatic dosage OTHER DIAGNOSTICS ▪ Genetic testing TREATMENT OTHER INTERVENTIONS ▪ Avoid triggers ESSENTIAL FRUCTOSURIA osms.it/essential-fructosuria PATHOLOGY & CAUSES ▪ Benign disease; impaired fructose metabolism → increased excretion in urine CAUSES ▪ Autosomal recessive mutation in fructokinase, AKA ketohexokinase (KHK) ▫ First enzyme in fructose metabolism ▪ Intake of fructose-rich food/fructose-related sugar (e.g. sucrose, sorbitol) → increase of fructose in blood → excretion of fructose in urine SIGNS & SYMPTOMS ▪ Asymptomatic 238 OSMOSIS.ORG DIAGNOSIS LAB RESULTS ▪ Positivity for reducing substances in urine TREATMENT OTHER INTERVENTIONS ▪ No treatment necessary
Chapter 41 Carbohydrate Metabolism Disorders GALACTOSEMIA osms.it/galactosemia PATHOLOGY & CAUSES ▪ Disease characterized by altered metabolism of galactose CAUSES ▪ Autosomal recessive disorder SIGNS & SYMPTOMS ▪ ▪ ▪ ▪ ▪ FTT Vomiting, diarrhea with lactation Jaundice, hepatomegaly Cataract Intellectual disability, lethargy, speech disorder, altered muscle coordination (ataxia) Three possible mutations ▪ Galactose-1-phosphate uridyl transferase (GALT) deﬁciency (most common) ▫ Accumulation of galactose-1-phosphate + alternative metabolic pathway activation → accumulation of galactose metabolites (galactitol, galactonate) ▪ Galactokinase deﬁciency (uncommon) ▫ Less severe, often asymptomatic ▪ Uridine diphosphate (UDP) galactose-4epimerase deﬁciency (uncommon) LAB RESULTS COMPLICATIONS OTHER INTERVENTIONS ▪ Metabolites accumulate in ▫ Eyes: increasing osmotic pressure → water attraction → opaciﬁcation of lens (cataract) ▫ Liver: fatty alteration, cirrhosis ▫ Brain: cell damage, edema, gliosis ▫ Kidney: prevent amino acid reabsorption → aminoaciduria ▪ Altered neutrophil activity → increased risk of sepsis from E.coli ▪ Gonadal failure, hemolysis, coagulopathy DIAGNOSIS ▪ Routinely screened in newborns ▫ Dosage of enzymes involved in galactose metabolism TREATMENT ▪ Elimination of galactose from diet OSMOSIS.ORG 239
HEREDITARY FRUCTOSE INTOLERANCE osms.it/hereditary-fructose-intolerance PATHOLOGY & CAUSES ▪ Disease characterized by alteration of fructose metabolism CAUSES ▪ Autosomal recessive mutation in liver aldolase (aldolase B) ▪ Aldolase B deﬁciency → fructose 1-phosphate buildup → ▫ Local fructose toxicity → liver cell death ▫ Hypoglycemia ▫ Adenosine triphosphate (ATP), phosphate depletion → inhibition of protein synthesis → hepatic, renal damage SIGNS & SYMPTOMS ▪ Avoidance of foods containing fructose (e.g. fruit, juice) ▪ Acute ingestion of fructose/compounds which contain fructose (e.g. sucrose, sorbitol) → nausea, vomiting; restlessness; pallor; sweating, trembling; lethargy, apathy; convulsions; coma ▪ Repeated ingestion of fructose → failure to thrive (FTT); liver disease (e.g. jaundice, hepatomegaly); kidney disease 240 OSMOSIS.ORG DIAGNOSIS OTHER DIAGNOSTICS ▪ Nutritional history, clinical presentation ▪ Genetic testing TREATMENT OTHER INTERVENTIONS ▪ Elimination of fructose from diet
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This Osmosis High-Yield Note provides an overview of Carbohydrate metabolism disorders essentials. All Osmosis Notes are clearly laid-out and contain striking images, tables, and diagrams to help visual learners understand complex topics quickly and efficiently. Find more information about Carbohydrate metabolism disorders by visiting the associated Learn Page.