Adrenal Glands and Metabolism

Adrenal Glands Overview

  • The adrenal glands interact with the hypothalamus-pituitary axis for hormone production.

Hormonal Regulation

  • Corticotropin-releasing hormone (CRH): Induces production of ACTH in the anterior pituitary.
  • Adrenocorticotropic hormone (ACTH): Stimulates adrenal cortex to produce hormones.

Hormones Produced by Adrenal Cortex

  • Types of Hormones:
    • Glucocorticoids (e.g., cortisol)
    • Mineralocorticoids (e.g., aldosterone)
    • Sex hormones
  • Functions: Glucocorticoids control sugar metabolism; mineralocorticoids regulate sodium and potassium balance.

Glucocorticoids

  • Cortisol:
    • Catabolic, breaks down resources under stress.
    • Increases blood sugar, suppresses immune function, causes muscle breakdown.
  • Cortisol Release: Triggered by stress, regulated through negative feedback to hypothalamus.

Mineralocorticoids

  • Aldosterone:
    • Regulates fluid balance, retains sodium/water, excretes potassium.

Adrenal Insufficiency

  • Addison’s Disease: Chronic adrenal insufficiency, can be primary (adrenal damage) or secondary (pituitary damage).
  • Symptoms: Fatigue, low blood sugar, fluid imbalance, hyperpigmentation.
  • Treatment: Hormone replacement therapy (hydrocortisone, fludrocortisone).

Addisonian Crisis

  • Definition: Severe acute adrenal insufficiency, life-threatening due to lack of cortisol and aldosterone.
  • Causes: Stress, illness, surgery.
  • Symptoms: Hypovolemia, hypotension, electrolyte imbalance.

Adrenal Excess Conditions

  • Cushing’s Disease: Pituitary tumor causing excessive ACTH.
  • Cushing Syndrome: Hypercortisolism with various clinical symptoms (e.g., obesity, skin issues).

Tumors of the Adrenal Gland

  • Pheochromocytoma: Tumor in the adrenal medulla producing excess epinephrine; causes hypertension and increased heart rate.

Pancreas Summary

  • Endocrine Function: Produces hormones regulating glucose metabolism.
  • Key Hormones:
    • Insulin: Lowers blood glucose, promotes uptake.
    • Glucagon: Raises blood glucose via glycogenolysis and gluconeogenesis.
    • Amylin: Slows glucose absorption.
    • Somatostatin: Decreases GI activity, suppresses insulin/glucagon.

Diabetes Mellitus Overview

  • Types:
    • Type 1 Diabetes: No insulin production (autoimmune destruction of beta cells).
    • Type 2 Diabetes: Insulin resistance; insufficient or malfunctioning insulin.
  • Symptoms: Polydipsia, polyuria, polyphagia.
  • Diagnosis: Blood tests (casual, fasting, A1C).

Insulin and Glucose Regulation

  • Insulin Actions: Stimulates glucose uptake, amino acid delivery, and various metabolic activities.
  • Insulin Resistance Components:
    • Inadequate insulin production
    • Ineffective insulin
    • Dysfunctional receptors.

Gestational Diabetes

  • Can develop during pregnancy. Often resolves post-pregnancy but may persist. Requires monitoring and treatment with insulin.