Introduction

Question 1

3 Classes of Hormones

Answer 1

1. Peptide & 2. Monoamine
   - Peptide: Insulin, ACTH, TRH
   - Monoamine: Epinephrine, Serotonin
   - Cell membrane receptors
   - activate 2nd messenger membrane channel
2. Hydrophobic: Steroids, Vitamin D3, T3
   - Have nuclear receptor
   - Activate transcription factor
   - transport in blood via plasma binding protein

Question 2

Tropic vs. Target Hormones

Answer 2

Trophic hormones: control levels of Target Hormones

• e.g., Hypothalamic-Pituitary Axis
• Often under negative feedback by the target hormones
• May stimulate or suppress target hormones

Question 3

Hormone Measurement & Variability

Answer 3

Measurement techniques:

• Bioassay
• Immunoassay
• Chemical Assay

Peptide Hormones:
- variability in isoforms
- Bioactivity: improper peptide sequence may affect ability to bind to receptor
vs.
- Immunoactivity: variability in how antibodies interact with particular isoform

Question 4

Etiologies of Hormone Deficiency

Answer 4

- Gland destruction (autoimmune,
infarction, trauma, etc)
- Abnormal gland development
- Bioinactive hormone
   » Abnormal synthesis
   » Abnormal prohormone processing

Question 5

Stimulation Testing

Answer 5

• Useful for evaluating HORMONE DEFICIENCY
• goal is to provide a physiologic or pharmacologic stimulus to hormone secretion and measure the hormone response

Example:
Pituitary function:
- Hypoglycemia normally stimulates cortisol
and growth hormone secretion (both restore blood glucose to normal)
- Could administer insulin to induce hypoglycemia; normal response would stimulate cortisol & GH

Adrenal Function:
- Aldosterone normally increases in response
to acute volume depletion induced by diuretic
- Cortisol normally increases in response to
synthetic ACTH (cosyntropin)

Question 6

Hormone Excess Classification & Diagnosis

Answer 6

Classification
» Target gland autonomy (Primary)
» Tropic hormone autonomy (Secondary)
» Ectopic hormone production

Diagnosis
» Characteristic clinical syndrome
» Elevated target hormone level
» Target hormone does not suppress
» Tropic hormone low (primary autonomy)
» Tropic hormone “normal” or high (secondary
autonomy or ectopic)

Question 7

Suppression Test

Answer 7

• useful for evaluating AUTONOMOUS HORMONE PRODUCTION

- perform maneuvers that should normally suppress hormone secretion and we measure the response

Question 8

Hormone Resistance Classification & Diagnosis

Answer 8

Classification

• Receptor defect
• Post receptor defect
• Endogenous receptor blocker

Diagnosis
» Variable clinical syndrome with features
consistent with hormone deficiency
» Target hormone level normal or elevated
» Diminished or absent response to
exogenous hormone

Testicular Feminization in 46XY:
- Male levels of testosterone, but abnormal testosterone receptors –> female body habitus

Severe insulin resistance type B:
» Anti-insulin receptor antibodies present
» Hyperglycemia despite high insulin level

Question 9

Target Cell Activation Classification & Diagnosis

Answer 9

Classification
» Receptor-activating mutation
» Post-receptor autonomy
» Endogenous hormone agonist

Diagnosis
» Clinical syndrome consistent with hormone
excess
» Hormone level low

Question 10

McCune Albright Syndrome

Answer 10

• Clinical features: pseudoprecocious puberty, Cushing syndrome, thyrotoxicosis, café au spots, fibrous dysplasia of bone, etc.
  » Pituitary tropic hormones (ACTH, TSH, LH, FSH) are low
  » Due to Gs constitutive activating mutations

Question 11

Humoral hypercalcemia of malignancy

Answer 11

• Hypercalcemia
  » Parathyroid hormone (PTH) low
  » “PTH-related” peptide present