CC Sem 3 Week 11 409

CC Sem 3 Week 11 Overview

  • NUR 409 Module 9
  • NUR 417 Module 5-6
  • NUR 417 Exam 2 Overview

NUR 409 Module 9: Mastering Metabolism & The Endocrine System

Hypofunction and Hyperfunction

  • A Clinical Guide to Assessment, Pathophysiology, and Nursing Care.
  • The Scales of Homeostasis

The Engine of Homeostasis

Core Principle 1

  • Bloodstream hormone concentrations are maintained at a constant level based on physiological need in a healthy state.
  • Inhibition (Feedback)
  • Central Nervous System involvement

Feedback Mechanisms

  • Negative Feedback Loop
      - Describes how hormone concentrations are regulated.
  • Override Mechanism
      - The CNS can stimulate or suppress the negative feedback loop via sympathetic or parasympathetic responses.

The Brake and Accelerator Systems

  1. Brake System:
       - Hormone production rate is inhibited when hormone concentration increases.
  2. Accelerator System:
       - Rate of hormone production increases when concentration decreases.

The Endocrine Diagnostic Dashboard

Assessment of Fluid and Electrolytes

  • Focus: Pituitary function
Key Lab Tests
  1. Fluid & Electrolytes:
       - Serum Sodium (Na)
       - Serum Potassium (K)
       - Serum Osmolality
       - Urine Specific Gravity
  2. Metabolic Rate:
       - Thyroid hormone assessment:
         - Thyroid Stimulating Hormone (TSH)
         - Triiodothyronine (T3) & Thyroxine (T4)
       - Diagnostics: Ultrasound, Thyroid Scan, Radioactive Iodine Therapy
  3. Stress & Output:
       - Serum Cortisol Levels
       - Diagnostics: Fluid Deprivation Test, Desmopressin Challenge Test

Water Balance: Pituitary Gland Dysfunction

Diabetes Insipidus (DI)

Mechanism
  • Characterized by decreased ADH leading to excess water loss.
Clinical Profile
  • Symptoms include excessive thirst, hypovolemia, and urine output of up to 20L/day.
Key Labs
  • Elevated Serum Sodium
  • Decreased Urine Osmolality
  • Decreased Specific Gravity (<1.005)
  • Hallmark: Dehydration

SIADH (Syndrome of Inappropriate Antidiuretic Hormone Secretion)

Mechanism
  • Characterized by increased ADH leading to water retention.
Clinical Profile
  • Symptoms include brain swelling/edema and risk of seizures if sodium drops below ~115 mEq/L.
Key Labs
  • Decreased Serum Sodium (dilutional hyponatremia)
  • Elevated Urine Osmolality
  • Elevated Specific Gravity (>1.030)
  • Oliguria (<20 mL/hr)

Clinical Interventions for Fluid Imbalance

Diabetes Insipidus (DI) Management Pathway

  1. Monitor & Replace Fluids (Continuous)
  2. Check Neuro Status & Mucous Membranes
  3. Monitor Vitals (watch for dropped BP, elevated HR)
Clinical Pearl
  • Vasopressin Therapy Indicator:
      - When administering vasopressin (DDAVP), the primary therapeutic indicator of success is a decrease in urine output, not a change in blood sugar or blood pressure.

SIADH Management Pathway

  1. Assess Nonendocrine Risks
  2. Implement Seizure Precautions (due to hyponatremia)
  3. Strict I&O Monitoring (especially for age >60 and patients with lung cancer)
Clinical Pearl
  • Post-Op Alert:
      - A patient developing oliguria following a craniotomy should be highly suspected of developing SIADH.

The Metabolic Engine: Thyroid Function

Hypothyroidism (Hashimoto's Disease)

Mechanism
  • Autoimmune attack leads to decreased metabolic activity.
Presentation
  • Symptoms include cold intolerance, bradycardia, weight gain despite unchanged diet, hair loss/receding hairline, constipation, masklike face, and thickened skin.
Diagnostic Marker
  • ELEVATION in TSH as the pituitary tries to stimulate the underactive thyroid.

Hyperthyroidism (Graves' Disease)

Mechanism
  • Antibodies bind to TSH, causing excessive production of T3 and T4.
Presentation
  • Symptoms include heat intolerance, tachycardia, weight loss, exophthalmos (bulging eyes), flushing, and frequent emotional changes.
Diagnostic Marker
  • DECREASED TSH level, significantly below reference ranges.

Thyroid Emergencies: Pushing into the Red Zone

Myxedema Coma (Extreme Hypothyroidism)

Profile
  • Hypothermic, unconscious, severe respiratory depression, facial and periorbital non-pitting edema.
Priority Actions
  • Manage cardiopulmonary status.
  • Implement aspiration precautions due to laryngeal edema and tongue thickening.
  • Administer fluids cautiously to avoid water intoxication.
  • Avoid the use of heating pads (risk of burn and vascular collapse).

Thyroid Storm (Extreme Hyperthyroidism)

Profile
  • Hyperpyrexia (temperature >101.3°F to 105.8°F), extreme tachycardia (>130 bpm), severe agitation/delirium, often precipitated by stress/injury.
Priority Actions
  • Immediately reduce temperature using cooling blankets and acetaminophen.
  • DO NOT administer aspirin (it displaces thyroid hormone and exacerbates hypermetabolism).
  • Maintain a low-stimulus, quiet environment.
  • Administer PTU (propylthiouracil)/methimazole and hydrocortisone.

Restoring Metabolic Balance

Levothyroxine Therapy

  1. Protocol:
       - Lifelong replacement therapy; discontinue only after consulting when symptoms improve.
  2. Therapeutic Goal:
       - A decrease in TSH levels indicates medication effectiveness and restoration of the feedback loop.
  3. Toxicity Alert: