Adrenal Gland Disorders Study Notes

Adrenal Gland Anatomy and Hormone Regulation

• Adrenal gland location and organization

  • Located above each kidney

  • Outer cortex and inner medulla

  • Cortex consists of three zones with distinct steroidogenic outputs:

  • Zona glomerulosa → mineralocorticoids (Aldosterone)

  • Zona fasciculata → glucocorticoids (Cortisol)

  • Zona reticularis → gonadocorticoids (Androgen)

  • Inner medulla contains chromaffin cells that secrete catecholamines (Adrenaline and Noradrenaline)

• Regulation of adrenal hormones (HPA axis and sympathetic inputs)

  • Hypothalamus releases CRH (corticotropin-releasing hormone)

  • Pituitary gland releases ACTH (adrenocorticotropic hormone)

  • Adrenal cortex produces cortisol (glucocorticoid) in response to ACTH

  • Adrenal medulla is innervated by sympathetic nerves and secretes catecholamines (Adrenaline and Noradrenaline) directly

  • The cascade links to systemic effects via cortisol and catecholamines

  • Hormones associated with adrenal gland function include}

  • Cortisol (stress response, metabolism, immune modulation)

  • Aldosterone (sodium and water retention, potassium excretion via kidney)

  • Androgens (gonadal effects; minor adrenal source)

  • Catecholamines (acute sympathetic responses: fight/flight)

Actions of Cortisol

• Liver- Increases gluconeogenesis from amino acids and fatty acids

  • Decreases glycogen and protein synthesis

• Adipose tissue and muscle- Decreases glucose uptake and utilization

  • Increases protein catabolism and lipolysis

• Vascular system- Increases vascular reactivity

• Immune and tissue effects- Long-term immunosuppressive effects reduce wound healing

• Systemic/survival roles- Supports the long-term stress response

  • Suppresses non-essential organ functions (e.g., digestion, reproduction) to mobilize glucose stores and help maintain blood pressure

Actions of Aldosterone

• Target: kidney

• Regulatory role- Increases sodium (and water) reabsorption via the Renin–Angiotensin–Aldosterone system (RAAS)

  • Regulates blood levels of potassium by increasing potassium excretion (decreases potassium reabsorption)

Hyposecretion of Adrenocortical Hormones (Cortisol & Aldosterone) – Addison Disease

• Causes- Autoimmune destruction of the adrenal cortex

  • Infections/disease (e.g., Tuberculosis)

  • Adrenal hemorrhage

• Pathophysiology- Increased ACTH due to loss of cortisol feedback → hyperpigmentation of the skin (ACTH shares precursors with melanocyte-stimulating hormone)

  • Addison Disease as the clinical syndrome when cortisol and aldosterone are deficient

• Clinical features due to specific deficiencies- Decreased Aldosterone

  • Hyponatremia (Na+), Hyperkalemia (K+)

  • Dehydration and hypotension

  • Weight loss

  • Muscle weakness and potential cardiac arrhythmias

  • Nausea, vomiting, and diarrhea (gastrointestinal symptoms)

  • Decreased Cortisol

  • Hypoglycemia

  • Irritability, depression, confusion, lethargy

  • Decreased Androgens

  • Loss of axillary and pubic hair

  • Loss of libido and amenorrhea

Hypersecretion of Adrenocortical Hormones – Cushing’s Syndrome

• Causes- Endogenous sources: adrenal tumour or pituitary tumour (Cushing’s disease)

  • Exogenous: corticosteroid administration

• Hypercortisolism cascade- Elevated cortisol leads to metabolic and systemic changes

  • Hyperglycemia → Hyperinsulinemia and increased fat deposition

• Common phenotypic features- Weight gain with trunk obesity and fat distributions (Moon face, buffalo hump)

  • Muscle and bone wasting due to protein catabolism

  • Osteoporosis with fractures and potentially kyphosis; may contribute to kidney stones

  • Increased androgens causing hirsutism, oligomenorrhea, deepening of voice, acne

  • Decreased libido

Other Common Clinical Manifestations and Consequences

• Cardiovascular and integumentary effects- Hypertension

  • Thin skin with purple striae

  • Easy bruising

• Pigmentation and immune effects- Hyperpigmentation (often due to elevated ACTH)

  • Increased susceptibility to infection; poor wound healing

• Neurological and mood effects- Mood swings, irritability, depression or euphoria

Summary and Learning Objectives (Recap)

• You should be able to:- Describe the causes of hyposecretion and hypersecretion of adrenal hormones (cortisol, aldosterone, androgens)

  • Describe the symptoms associated with hyposecretion and hypersecretion

  • Explain the pathophysiology underlying the adrenal hormone disorders described (Addison’s and Cushing’s syndromes)

• Foundational context and relevance- Relates to regulation of metabolism, fluid balance, stress response, immune function, and reproductive physiology

  • Demonstrates how endocrine feedback loops (hypothalamus-pituitary-adrenal axis) and adrenal outputs interact to maintain homeostasis

  • Clinical implications include potential for metabolic derangements, cardiovascular risk, immune compromise, and quality-of-life impacts

Conceptual Connections and Practical Implications

• Clinical reasoning- Distinguish between cortisol-driven and aldosterone-driven symptoms when patient presents with fatigue, hypotension, hyponatremia/hyperkalemia, or features of Cushing’s

• Therapeutic considerations (high-level)- Treatment strategies depend on whether the issue is hypo- or hypersecretion and whether etiologies are autoimmune, neoplastic, infectious, or iatrogenic (steroid-induced)

• Ethical and societal context- Not explicitly discussed in the material; standard medical ethics apply to diagnosis, treatment, and patient autonomy in managing chronic endocrine disorders