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Questions and Answers
Which of the following is a key difference between pasireotide and other somatostatin analogs like octreotide or lanreotide?
Which of the following is a key difference between pasireotide and other somatostatin analogs like octreotide or lanreotide?
Which of the following describes the mechanism of action of pegvisomant?
Which of the following describes the mechanism of action of pegvisomant?
Which of the following is NOT a common side effect of pegvisomant therapy?
Which of the following is NOT a common side effect of pegvisomant therapy?
Which of the following is a common cause of hyperprolactinemia?
Which of the following is a common cause of hyperprolactinemia?
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What is the principal mechanism through which bromocriptine and cabergoline reduce prolactin levels?
What is the principal mechanism through which bromocriptine and cabergoline reduce prolactin levels?
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Which hormone is NOT derived from proopiomelanocortin (POMC)?
Which hormone is NOT derived from proopiomelanocortin (POMC)?
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Which of the following hypothalamic hormones inhibits the release of growth hormone (GH) from the pituitary gland?
Which of the following hypothalamic hormones inhibits the release of growth hormone (GH) from the pituitary gland?
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A patient with a growth hormone deficiency is being treated with somatropin. Which of the following effects would NOT be expected as a result of this treatment?
A patient with a growth hormone deficiency is being treated with somatropin. Which of the following effects would NOT be expected as a result of this treatment?
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What is the primary indirect mechanism of action of somatropin?
What is the primary indirect mechanism of action of somatropin?
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Which of the following is a potential indication for the use of growth hormone (somatropin)?
Which of the following is a potential indication for the use of growth hormone (somatropin)?
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Besides growth hormone (GH), which other anterior pituitary hormone is inhibited by somatostatin?
Besides growth hormone (GH), which other anterior pituitary hormone is inhibited by somatostatin?
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Which of the following hormones is NOT a glycoprotein hormone?
Which of the following hormones is NOT a glycoprotein hormone?
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What is the effect of growth hormone on insulin receptor sensitivity?
What is the effect of growth hormone on insulin receptor sensitivity?
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Which of the following is a common side effect of growth hormone therapy?
Which of the following is a common side effect of growth hormone therapy?
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What is the primary indication for the use of mecasermin?
What is the primary indication for the use of mecasermin?
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How does the mechanism of action of somatostatin analogs contribute to a common side effect?
How does the mechanism of action of somatostatin analogs contribute to a common side effect?
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A patient on cabergoline for acromegaly reports dizziness and headache. How should this be interpreted?
A patient on cabergoline for acromegaly reports dizziness and headache. How should this be interpreted?
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What distinguishes octreotide from lanreotide in the treatment of acromegaly?
What distinguishes octreotide from lanreotide in the treatment of acromegaly?
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Why is caution advised when using growth hormone in diabetic patients on insulin therapy?
Why is caution advised when using growth hormone in diabetic patients on insulin therapy?
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What is the primary difference in half-life between bromocriptine and cabergoline?
What is the primary difference in half-life between bromocriptine and cabergoline?
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A patient starts a new medication for acromegaly and experiences significant diarrhea, nausea, and abdominal cramps. Which type of medication is most likely causing these symptoms?
A patient starts a new medication for acromegaly and experiences significant diarrhea, nausea, and abdominal cramps. Which type of medication is most likely causing these symptoms?
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Study Notes
Anterior Pituitary Hormones
- The anterior pituitary secretes various hormones including TSH, ACTH, LH, FSH, GH, and prolactin.
Learning Objectives
- Students should identify and describe hormones secreted by the anterior pituitary.
- Students should identify and describe the mechanisms of action of agents used to treat GH deficiency and overproduction in adults and children.
- Students should identify and describe adverse effects of agents used to treat GH and prolactin deficiency/hypersecretion in adults and children.
- Students should identify and describe the indications for use of GH, mecasermin/mecasermin rinfabate.
Anterior Pituitary Hormone Classification
- POMC-derived hormones: ACTH, α-MSH
- Somatotropes: GH, PRL
- Glycoprotein hormones: LH, FSH, hCG, TSH
Hypothalamus-Pituitary Axis
- Hypothalamic releasing hormones regulate pituitary hormone release, including CRH for ACTH, GHRH for GH, GnRH for LH/FSH, and TRH for TSH.
- Somatostatin (SST) inhibits pituitary GH and TSH release.
- Dopamine (DA) inhibits pituitary PRL release.
Treatments for GH Deficiency
- Somatropin is a growth hormone treatment.
- The structure of somatropin is a peptide hormone with 191 amino acid residues.
Physiological Actions of GH
- Impairs glucose uptake in tissues.
- Lowers glucose utilization in peripheral tissues.
- Increases lipolysis.
- Increases muscle mass.
- Increases gluconeogenesis in hepatocytes.
- Decreases insulin receptor sensitivity.
- Decreases post-receptor insulin action.
GH Mechanism of Action
- GH acts indirectly via a liver-derived signal, IGF-1.
- IGF-1 stimulates clonal expansion and differentiation/proliferation in target tissues.
Indications for Use of GH
- GH deficiency, short stature in children.
- Treatment of pediatric patients with short stature.
- Prader-Willi syndrome with growth failure.
- Turner syndrome, idiopathic short stature.
- Treatment of wasting in patients with AIDS.
- Treatment of patients with short bowel syndrome.
Side Effects of GH Treatments
- Pancreatitis, gynecomastia, carpal tunnel syndrome, CYP450 induction, peripheral edema, myalgias, and arthalgias.
- Caution with diabetic patients on insulin therapy.
- Increased risk of asphyxiation in severely obese patients with Prader-Willi syndrome and airway obstruction.
Mecasermin/Mecasermin Rinfabate
- Indications: Growth failure in children with primary IGF-1 deficiency (IGFD), GH gene deletion with developed neutralizing antibodies to GH.
- Mechanism: Provides IGF-1.
- Route: Parenteral (s.c.).
- Side Effects: Hypoglycemia, intracranial hypertension, adenotonsillar hypertrophy.
Treatments for GH Excess (Acromegaly) - Dopamine Agonists
- Bromocriptine (short half-life)
- Cabergoline (longer half-life, high affinity for D2 receptors)
Treatments for GH Excess (Acromegaly) - Somatostatin Analogs
- Octreotide
- Sandostatin
- Lanreotide (Depot)
- Pasireotide
Side Effects of Somatostatin Analogs
- Most common: Diarrhea, nausea, abdominal cramps, malabsorption of fat and flatulence.
- Cholelithiasis is common, but most patients are asymptomatic.
- Octreotide/lanreotide: injection-site pain, conduction abnormalities, biliary tract disorders, subclinical hypothyroidism, abnormalities with glucose metabolism.
- Pasireotide: similar to octreotide/lanreotide EXCEPT for higher incidence of hyperglycemia.
Treatments for GH Excess (Acromegaly) - GH Receptor Antagonists
- Pegvisomant
- Route: Parenteral (s.c.).
- Mechanism: Blocks GH receptor
- Side Effects: Injection site pain, GI complaints (nausea and diarrhea), significant elevations in hepatic aminotransferase (25%), Flu-like symptoms, tumor growth (in small fraction of patients).
Treatments for Hyperprolactinemia
- Most common causes: Prolactinomas, DA receptor antagonists (antipsychotics, oral contraceptives), DA blockade in Tuberoinfundibular pathway.
- Most common drugs used: Bromocriptine, Cabergoline.
- Mechanism: Agonist at DA receptor (Tuberoinfundibular pathway).
- Both drugs are Category B for pregnancy
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Description
Test your knowledge on the various hormones secreted by the anterior pituitary, including TSH, ACTH, and GH. This quiz covers their mechanisms of action, treatment for deficiencies, and associated adverse effects. Learn how the hypothalamus regulates these hormones for a comprehensive understanding.
