19.3 Metabolic Disorders and Diseases

Metabolic disorders disrupt the body's ability to process nutrients and energy. From diabetes to inborn errors of metabolism, these conditions highlight the intricate balance of biochemical pathways essential for health.

Understanding metabolic diseases reveals the interconnectedness of our body's systems. By examining how these disorders affect energy production and nutrient processing, we gain insights into the complex network of metabolic pathways and their regulation.

Metabolic Disorders

Diabetes Mellitus and Obesity

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Top images from around the web for Diabetes Mellitus and Obesity

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  Frontiers | Gut Microbiota as a Trigger for Metabolic Inflammation in Obesity and Type 2 Diabetes View original

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  Frontiers | The crucial role and mechanism of insulin resistance in metabolic disease View original

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  Frontiers | Diabetes and Sarcopenic Obesity: Pathogenesis, Diagnosis, and Treatments View original

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  Frontiers | Gut Microbiota as a Trigger for Metabolic Inflammation in Obesity and Type 2 Diabetes View original

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  Frontiers | The crucial role and mechanism of insulin resistance in metabolic disease View original

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• Diabetes mellitus disrupts glucose metabolism due to insufficient insulin production or insulin resistance
  • Type 1 diabetes results from autoimmune destruction of pancreatic β-cells
  • Type 2 diabetes involves decreased insulin sensitivity in target tissues
• Obesity develops from chronic energy imbalance leading to excess fat accumulation
  • Body Mass Index (BMI) ≥ 30 kg/m² indicates obesity
  • Contributes to insulin resistance and increases risk of type 2 diabetes
• Both conditions involve dysregulation of energy homeostasis and metabolism
• Long-term complications include cardiovascular disease, neuropathy, and nephropathy

Metabolic Syndrome and Ketoacidosis

• Metabolic syndrome comprises a cluster of conditions increasing cardiovascular risk
  • Includes abdominal obesity, hypertension, dyslipidemia, and insulin resistance
  • Diagnosis requires presence of at least three components
• Ketoacidosis occurs when the body breaks down fatty acids for energy instead of glucose
  • Produces ketone bodies (acetoacetate, β-hydroxybutyrate, acetone)
  • Can lead to dangerously low blood pH (acidosis)
  • Common in uncontrolled type 1 diabetes or severe insulin deficiency
• Both conditions reflect severe metabolic imbalances requiring prompt medical intervention

Inborn Errors of Metabolism

Phenylketonuria and Glycogen Storage Diseases

• Phenylketonuria (PKU) results from deficiency in phenylalanine hydroxylase enzyme
  • Leads to accumulation of phenylalanine and its metabolites in blood and tissues
  • Causes intellectual disability if left untreated
  • Managed through dietary restriction of phenylalanine
• Glycogen storage diseases involve defects in glycogen synthesis or breakdown
  • Type I (von Gierke's disease) lacks glucose-6-phosphatase
  • Type II (Pompe's disease) lacks acid α-glucosidase
  • Symptoms vary but often include hypoglycemia, hepatomegaly, and muscle weakness
• Both disorders highlight the importance of early detection through newborn screening

Fatty Acid Oxidation Disorders and Mitochondrial Diseases

• Fatty acid oxidation disorders impair the breakdown of fatty acids for energy
  • Medium-chain acyl-CoA dehydrogenase (MCAD) deficiency most common
  • Symptoms include hypoglycemia, lethargy, and seizures during fasting or illness
• Mitochondrial diseases affect cellular energy production
  • Can result from mutations in mitochondrial or nuclear DNA
  • Leber's hereditary optic neuropathy causes vision loss
  • Mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episodes (MELAS) syndrome affects multiple organ systems
• Both groups of disorders underscore the critical role of mitochondria in metabolism

Other Metabolic Diseases

Gout and Hyperuricemia

• Gout results from elevated uric acid levels in the blood (hyperuricemia)
  • Uric acid crystals deposit in joints causing inflammation and severe pain
  • Commonly affects the big toe (podagra)
  • Risk factors include diet high in purines (red meat, organ meats), alcohol consumption
• Hyperuricemia occurs when uric acid production exceeds excretion
  • Normal uric acid levels: 3.5-7.2 mg/dL in men, 2.6-6.0 mg/dL in women
  • Can lead to kidney stones and chronic kidney disease if untreated
• Management involves dietary modifications, medications to reduce uric acid production or increase excretion

Hyperlipidemia and Hypercholesterolemia

• Hyperlipidemia refers to elevated levels of lipids (fats) in the blood
  • Includes elevated triglycerides and cholesterol
  • Can be primary (genetic) or secondary (due to other conditions or lifestyle factors)
• Hypercholesterolemia specifically involves high blood cholesterol levels
  • LDL cholesterol ≥ 130 mg/dL considered high
  • Familial hypercholesterolemia caused by genetic defects in LDL receptor function
• Both conditions increase risk of atherosclerosis and cardiovascular disease
  • Treatment includes lifestyle changes (diet, exercise) and medications (statins)
• Regular lipid profile monitoring essential for early detection and management