The Endocrine System, Pathology, Hormone Evolution

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Three basic patterns of endocrine pathologies:
Hormone excess, Hormone deficiency, and abnormal responsiveness of target tissues to a hormone.

CRH-ACTH-Cortisol-Target Tissue-Response

Hypersecretion Exaggerates a Hormones Effects
Adenomas may cause hypersecretion.
Tumours, including non-endocrine tumours may secrete hormones.
Exogenous source of hormones, eg Exogenous Cortisol. Prolonged use may cause cellular atrophy.


Hyposecretion Diminishes or Eliminates a Hormones Effects
Most commonly due to atrophy of the endocrine gland.
Adrenal Gland atrophy secondary to tuberculosis, diminishing cortisol production

Receptor or Second Messenger Problems Cause Abnormal Tissue Responsiveness

  1. Downregulation
    1. Hyperinsulinemia - sustained levels of insulin cause the insulin receptors of target tissues to remove insulin receptors from the cell membrane. Patients suffering from hyperinsulinemia show signs of diabetes despite their high insulin levels.
  2. Receptor and Signal Transduction Abnormalities
    1. Testicular feminising syndrome
    2. Pseudohypoparathyroidism  - Signs of low parathyroid hormone even though the blood levels of the hormone are normal or elevated. Inherited defect of teh G protein that links the hormone to cAMP amplifier enzyme, adenyl cyclase. Because the signal transduction pathway does not respond to parathyroid hormone, and the signs of hormone deficiency appear.
Diagnosis of Endocrine Pathologies depends on the Complexity of the Reflex
  1. Pituitary is damaged by head trauma and ACTH secretion diminishes, the resulting cortisol deficiency is considered secondary hyposecretion of cortisol.
  2. Tumour of the pituitary - 
Hormone Evolution:

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