Metabolism (Week #3)

Metabolism

  • Definition of Metabolism: The sum of all chemical reactions that take place in every cell of the body, providing energy for the processes of life and synthesizing new cellular material.

Outcomes

  • Understanding of Metabolism/Sensation:

    • Understand and discuss the concept of metabolism.

    • Recognize patients with optimal metabolism, those at risk, and those experiencing poor metabolism.

    • Apply knowledge of pathophysiology to the care of patients with metabolic disorders.

    • Analyze physical assessment findings of patients with a selected metabolism disorder.

  • Continued Outcomes:

    • Identify and interpret laboratory studies for patients with metabolic disorders.

    • Apply principles of pharmacologic management for metabolic disorders.

    • Discuss nutritional management with metabolic disorders.

    • Collaborate with interdisciplinary teams for patients with metabolic disorders.

  • Further Outcomes:

    • Plan and prioritize nursing interventions for those with metabolic disorders.

    • Develop individualized teaching plans for patients with metabolic disorders.

    • Discuss risk factors for developing peripheral neuropathy.

    • Develop a plan of care for a patient with peripheral neuropathy.

Hormonal Regulation

  • Definition of Hormonal Regulation:

    • Physiological mechanisms that regulate the secretion and action of hormones associated with the endocrine system.

    • Hormonal regulation can be viewed from the perspective of the hormones and glands involved.

  • Scope of Hormonal Regulation:

    • Ranges from normal circulating hormone levels (based on physiological needs) to abnormal secretion (excess or deficiency).

Review of Endocrine System Anatomy and Physiology

  • Key Glands:

    • Anterior pituitary gland.

    • Pancreas.

    • Adrenal glands.

    • Posterior pituitary gland.

Hormonal Regulation Overview

  • Hormones Secreted From:

    • Hypothalamus.

    • Anterior Pituitary.

    • Posterior Pituitary.

    • Thyroid.

    • Parathyroid.

    • Adrenal Cortex.

    • Ovary.

    • Testes.

    • Pancreas.

Maintaining Hormonal Balance

  • Process Overview:

    • Hormones produced by glands impact target tissues and physiological effects.

    • Four Types of Feedback Control:

    • Negative feedback.

    • Positive feedback.

    • Biological rhythms.

    • Central nervous system control.

Consequences of Impaired Hormonal Regulation

  • Common Consequences Include:

    • Alterations in growth and development.

    • Alterations in cognition.

    • Alterations in metabolism.

    • Alterations in reproduction.

    • Changes in growth.

    • Altered adaptive responses.

    • Disruption of hormone production can lead to complications and possible lifetime hormonal replacement therapy.

Interrelated Concepts

  • Concepts interconnected with metabolism include:

    • Intracranial Regulation.

    • Fluid and Electrolytes.

    • Hormonal Regulation.

    • Stress.

    • Reproduction.

    • Development.

    • Glucose Regulation.

    • Nutrition.

Glucose Regulation

  • Definition of Glucose Regulation:

    • The process of maintaining optimal blood glucose levels.

    • The ultimate end result of glucose metabolism is cellular utilization of glucose for energy synthesis (adenosine triphosphate [ATP]).

  • Physiological Processes for Maintaining Glucose Balance:

    • Hormones that lower glucose: Insulin.

    • Counterregulatory hormones that raise glucose: Glucagon, Cortisol.

    • Problems arise when hormone production is deficient, excessive, or not balanced with blood glucose needs.

  • Key Terms in Glucose Regulation:

    • Glycogen: Major source of stored glucose found in the liver and muscles.

    • Glycogenolysis: The breakdown of glycogen to glucose.

    • Glucogenesis: The process of producing glucose from non-carbohydrates.

Normal Physiological Process of Glucose Regulation

  • Glucose Sources.

  • Role of Insulin: Facilitates movement of glucose across cell membranes into cells and prevents excessive breakdown of glycogen in the liver and muscles.

  • The Body Without Insulin: Complications arise when insulin is absent.

  • Counter-Regulatory Hormones:

    • Glucagon: Raises blood glucose levels by stimulating glycogenolysis and gluconeogenesis.

    • Cortisol: Increases blood sugar levels.

    • Epinephrine: Plays a role in the stress response by raising glucose levels.

    • Norepinephrine: Also assists in raising glucose levels during stress responses.

Overview of Diabetes Mellitus (DM)

  • Definition of Diabetes Mellitus:

    • Disorder characterized by hyperglycemia due to defects in insulin secretion, insulin action, or both, leading to abnormalities in carbohydrate and fat metabolism.

  • Types of Diabetes Mellitus:

    • Type 1 Diabetes Mellitus (T1D): Autoimmune disorder leading to destruction of beta cells, typically under age 30.

    • Type 2 Diabetes Mellitus (T2D): Characterized by excessive glucose production by the liver, impaired insulin secretion, and insulin resistance, primarily in liver, adipose, and muscle tissues.

    • Gestational Diabetes: Affects about 7% of all women, diagnosed through glucose tolerance test during pregnancy (24-28 weeks).

    • Other Specific Types: Includes maturity-onset diabetes of youth (type 2 in children) and latent autoimmune diabetes in adults (sometimes referred to as type 1.5).

Etiology and Types of Diabetes

  • Risk Factors for Diabetes:

    • Family history.

    • Obesity.

    • Age.

    • Hypertension (HTN).

    • Low HDL cholesterol (HDL < 35).

    • History of gestational diabetes.

    • Delivery of large babies.

  • Blood Glucose Homeostasis:

    • Body tissues and organs require a constant supply of glucose.

    • Organs like the brain, liver, intestines, and renal tubules do not need insulin for glucose entry.

    • Skeletal muscle, cardiac muscle, and adipose tissue require insulin to facilitate glucose entry.

  • Abnormalities in Diabetes:

    • Type 1 Diabetes results in loss of insulin production.

    • Type 2 Diabetes results in altered insulin production.

Diagnosis of Diabetes and Symptoms

  • Classic Symptoms of Hyperglycemia:

    • Elevated glucose leading to fluid and electrolyte imbalances (osmotic diuresis).

    • Polyuria: Excessive urination.

    • Polydipsia: Excessive thirst.

    • Polyphagia: Excessive eating.

Diagnostic Tests for Diabetes

  • Four diagnostic tests:

    • Hemoglobin A1C: ≥6.5% (normal level 4-6%).

    • Symptoms of Diabetes + Casual Plasma Glucose Concentration: >200 mg/dL.

    • Fasting Plasma Glucose (FPG): >126 mg/dL.

    • Two-Hour Plasma Glucose (PG) during Oral Glucose Tolerance Test (OGTT): >200 mg/dL.

  • Each test must be confirmed on a subsequent day with a different test.

Fasting Plasma Glucose Levels

  • Normal Fasting Glucose: 100 mg/dL (6.1 mmol/L).

  • Impaired Fasting Glucose: >100 mg/dL (6.1 mmol/L) and <126 mg/dL (7 mmol/L).

  • Diagnosis of Diabetes: >126 mg/dL (7 mmol/L).

Oral Glucose Tolerance Test (OGTT) Levels

  • Normal Glucose Tolerance: 2-Hour PG <140 mg/dL (7.8 mmol/L).

  • Impaired Glucose Tolerance: 2-Hour PG >140 mg/dL (7.8 mmol/L) and <200 mg/dL (11.1 mmol/L).

  • Diagnosis of Diabetes: 2-Hour PG >200 mg/dL (11.1 mmol/L).

  • FPG is recommended in clinical settings for non-pregnant adults.

Diabetes Management Monitoring

  • Fasting Blood Glucose (FBG): 70–110 mg/dL.

  • Hemoglobin (A1C): Average blood glucose over 2–3 months; elevated >6.5%.

  • Urine Glucose and Ketones Levels: Not as accurate for diagnosis.

  • Urine Test for Presence of Protein as Albumin: (Microalbuminuria).

  • Serum Cholesterol and Triglyceride Levels.

  • Serum Electrolytes: Can be lost in hyperglycemia.

Acute Complications of Diabetes

  • Hypoglycemia:

    • Common in Type 1 and Type 2 diabetes; called insulin shock or reaction.

    • Causes include mismatch between insulin intake, physical activity, carbohydrate availability, erroneous insulin dose, missed meals, alcohol intake, and certain medications.

    • Manifestations: Result from autonomic nervous system compensation; vary especially in older adults; sudden onset; severe cases may lead to death.

Signs and Symptoms of Hypoglycemia

  • Typical Symptoms:

    • Headache.

    • Sweaty.

    • Shaky.

    • Hungry.

    • Confused.

    • Dizzy.

    • Grumpy.

Treatment for Hypoglycemia

  • For Mild Symptoms: ~15 g of rapid-acting sugar; follow the 15/15 rule: wait 15 minutes, monitor blood glucose, consume another 15 g of carbohydrates.

  • Hospitalization if:

    • Blood glucose <50 mg/dL.

    • Coma, seizures, or altered behaviors.

    • Treated but unattended by a responsible adult for 12 hours.

  • For Conscious Patients: Administer 10–15 g of oral carbohydrate.

  • For Patients with Altered Consciousness:

    • Administer 20–50 mL of a 25–50% glucose solution.

    • Continuous IV infusion of glucose 10–20% at a rate of 50–200 mL/hr.

    • Severe insulin-induced hypoglycemia requires glucagon subcutaneous (SC), intramuscular (IM), or IV.

Diabetic Ketoacidosis (DKA)

  • Onset: Slow; can occur in both Type 1 and Type 2 diabetes but most common in Type 1.

  • Causes: Elevated glucose and deficient insulin.

  • Symptoms: Flushed skin, abdominal pain, fruity breath, decreased level of consciousness (LOC).

  • Diagnosis: Laboratory results show high blood sugar, high urine ketones, and decreased plasma pH (<7.3).

  • Treatment: Fluids, insulin, and electrolytes.

Hyperosmolar Hyperglycemic State (HHS)

  • Onset: Slow; occurs in older age or with reduced insulin production.

  • Symptoms: Flushed skin, lethargy, severe fluid loss, malaise, seizures.

  • Diagnosis: High glucose levels, normal ketones, reduced electrolytes, normal pH.

  • Treatment: Insulin, fluids, and electrolytes.

Lifespan Considerations

  • Older Adults:

    • Higher risk for additional complications alongside those found at younger ages, including polypharmacy, functional disabilities, cognitive impairment, depression, urinary incontinence, and falls.

    • Goals for Type 2 Diabetes management are similar to those in younger adults but with an increased risk for hypoglycemia.

Cultural Aspects of Diabetes

  • Risk Factors: Type 2 diabetes risk is higher among American Indians, African Americans, and Hispanics.

  • Cultural Factors: Diet and beliefs play a role in the management and perception of diabetes; nurses need to be sensitive to these cultural norms during care delivery.

Clinical Management of Glucose Regulation

  • Primary Prevention Strategies:

    • Manage body weight.

    • Exercise regularly.

    • Maintain a balanced diet.

    • Monitor glucose levels.

    • Ensure ongoing education.

Collaborative Interventions

  • Patient Education for Self Management:

    • Sick Days Rule.

    • Ongoing lab assessments and routine examinations.

    • Diabetic foot care.

  • Pharmacologic Therapy:

    • Insulin and oral antidiabetic agents; consider statin agents for cardiovascular health.

Insulin Preparations Overview

  • Types of Insulin Preparations:

    • Rapid Acting: e.g., aspart (NovoLog), glulisine (Apidra): onset 10-30 minutes, peak 30 minutes to 3 hours, duration 3-5 hours.

    • Short Acting: e.g., Regular (Humulin R, Novolin R): onset 30 minutes to 1 hour, peak 2-5 hours, duration 6-8 hours.

    • Intermediate Acting: e.g., NPH (Humulin N, Novolin N): onset 1.5 hours, peak 4-12 hours.

    • Long Acting: e.g., glargine (Lantus), detemir (Levemir): onset varies, no pronounced peak, duration 24+ hours.

Mixing Insulin Instructions

  1. Wash hands.

  2. Gently rotate NPH insulin bottle.

  3. Wipe off tops of insulin vials with alcohol sponge.

  4. Draw back air into the syringe equal to the total dose.

  5. Inject air equal to NPH dose into NPH vial, then remove the syringe.

  6. Inject air equal to regular dose into the regular vial.

  7. Invert regular insulin bottle and withdraw the regular insulin dose.

  8. Without adding more air to NPH vial, carefully withdraw NPH dose and add it to the regular insulin already in the syringe.

Oral Agents for Diabetes

  • Oral Agents Overview:

    • Biguanides: e.g., Metformin - decreases hepatic glucose production.

    • Thiazolidinediones: e.g., Rosiglitazone, Pioglitazone - improve peripheral insulin sensitivity.

    • Alpha-glucosidase Inhibitors: e.g., Acarbose, Miglitol - delay carbohydrate absorption.

    • Sulfonylureas and Short-acting Insulinotropic Agents: e.g., Glimepiride, Glipizide, Glyburide, Gliclazide - stimulate insulin secretion from pancreatic beta cells.

Consequences of Hyperglycemia

  • Short-Term Consequences:

    • Inadequate glucose reaching cells.

    • Dehydration.

  • Long-Term Consequences:

    • End-organ disease due to microvascular damage such as:

      • Retinopathy: Damage to the retina causing vision issues.

      • Nephropathy: Kidney dysfunction.

      • Peripheral Neuropathy: Damage to peripheral nerves causing pain/weakness.

      • Macrovascular Angiopathy: Increased risk for hypertension, cardiovascular, and peripheral vascular disease.

Interrelated Concepts of Glucose Regulation

  • Key Interrelated Concepts:

    • Adherence.

    • Family Dynamics.

    • Culture.

    • Nutrition.

    • Mobility.

    • Perfusion.

    • Immunity.

    • Sensory Perception.

    • Elimination.

    • Tissue Integrity.

    • Patient Education.

Chronic Complications of Diabetes

  • Macrovascular Complications (Large Vessel Disease):

    • Cardiovascular disease, including coronary artery disease (CAD), hypertension, and cerebrovascular disease (CVD).

  • Microvascular Complications (Small Vessel Disease):

    • Eye and vision complications (diabetic retinopathy).

    • Diabetic neuropathy.

    • Diabetic nephropathy.

    • Male erectile dysfunction.

Diabetic Retinopathy

  • Overview of Diabetic Retinopathy:

    • Most common cause of new blindness cases among adults aged 20-74 years.

Collaborative Management and Patient Education

  • Patient Education:

    • Teach patients about the importance of daily foot care, recognizing symptoms of neuropathy, and managing glucose levels.

    • Encourage a well-balanced diet, regular exercise, and regular monitoring of blood glucose levels.

  • Supporting Chronic Conditions:

    • Development of a multidisciplinary care plan that incorporates physical therapy, pharmacologic management, nutritional education, and psychological support for diabetes management.