Pituitary Hyperfunction

Question 1

The vast majority of Pituitary Tumors secrete what hormone(s)

Answer 1

Prolactin (50%)

Non-Secretory (40%)

Question 2

Functions of Prolactin

Answer 2

Milk PRODUCTION (not let-down)
Oppose action of Gonadotropins (FSH & LH) and estrogen
Inhibits GnRH release

Question 3

How might a Prolactinoma result in low testosterone in males?

Answer 3

Prolactin opposes the action of Gonadotrophins and inhibits GnRH release

Question 4

MOA for Hyperprolactinemia

Answer 4

Deficiency of Dopamine
Defective delivery of Dopamine
Insensitivity to Dopamine
Stimulation of Lactotroph cells (by oestrogen)

Question 5

What are some pathologies/diseases that can cause Hyperprolactinemia

Answer 5

Prolactinoma
Acromegaly
Pituitary stalk disease (or compression)
Renal insufficiency (dec. prolactin clearance)
Seizures
Cirrhosis
etc.

Question 6

Medications that can cause Hyperprolactinemia

Answer 6

Antihypertensives (Verapamil, Methydopa)
GI meds (Metoclopramide, Domperidone, H2 blockers)
Psych drugs (SSRIs, MAO inhibitors, Chlorpromazine, Atypicals)

Question 7

Signs/Symptoms of Hyperprolactinemia

Answer 7

Female:

• galactorrhea
• Menstrual irregularity
• Infertility
• loss of pubic hair

Male:

• galactorrhea
• Impotence (erectile dysfunction & dec. libido)
• Visual Field Abnormalities
• Extraocular Muscle Weakness
• loss of pubic hair

Question 8

The earliest change that occurs with Hyperprolactinemia (in females) is the loss of ____ and ___ due to the inhibition of _____ release from the Hypothalamus

Answer 8

LH and FSH; GnRH

*remember that prolactin opposes the actions of gonadotrophins and inhibits GnRH

Question 9

Treatment for Hyperprolactinemia

Answer 9

Dopamine agonist therapy (1st line)

Monitor w/o tx if asymptomatic with stable prolactin and no loss of sex hormones
*surgery and radiotherapy have limited use

Question 10

Examples of Dopamine Agonists (for Hyperprolactinemia treatment) (2 total)

Answer 10

Bromocriptine

Cabergoline

Question 11

Side Effects of Dopamine Agonist

Answer 11

Orthostatic Hypotension
Psychosis
Nausea & Vomiting
Sleep Disturbances

Question 12

Acromegaly is due to _______ excess in adults

Answer 12

Growth Hormone

Question 13

Signs of Acromegaly (GH excess)

Answer 13

Bone growth (acral changes like shoe size, ring size, hat size)
neuromuscular
Thickening of skin (heel pad)
Hypertension
Resp. problems
Cardiomyopathy

Question 14

IGF-I

Answer 14

insulin-like growth factor I (good for GH monitoring)

Question 15

Diagnostic methods for Acromegaly

Answer 15

1. Measure IGF-I (stable and unaffected by meal; more reliable than GH)
2. Failure to suppress GH < 1 ng/mL after oral glucose administration

Question 16

Which sign/symptom of Acromegaly (GH excess) has the most impact on mortality

Answer 16

Acromegaly + Cardiac disease (HTN, cardiomyopathy, etc.)

• life expectancy dropped by 10 YEARS!!

Question 17

Treatments for Acromegaly

Answer 17

Medication (1st line)

• Dopamine Agonists (direct inhibition of GH)
• Somatostatin Analogs (direct inhibition of GH)
• GH receptor antagonists (most potent)

Surgery
Radiotherapy

Question 18

Example of GH Receptor Antagonist

Answer 18

Pegvisomant

Question 19

The earliest presenting symptom in women with hyperprolactinemia is

Answer 19

infertility

* due to loss of mid-cycle surge of LH and FSH

Question 20

What symptoms always appears along with amenorrhea?

Answer 20

galactorrhea

Question 21

(T/F) Dopamine agonists reduce pituitary tumor size.

Answer 21

True

Question 22

_______ (organs) are stimulated by GH to synthesize _______ , which stimulate other target tissues

Answer 22

1. bone, muscle, fat, and liver

2. IGF-1

Question 23

Pattern of GH secretion

Answer 23

pulsatile

Question 24

Examples of Somatostatin analogs (for acromegaly treatment)

Answer 24

Octreotide
Lanreotide

• -otides

Question 25

Major pros of using D2 agonists for acromegaly tx

Answer 25

Pros: - GH suppression - Possible tumor shrinkage - serum IGF-1 normalizes in many patients

Question 26

Major pros and cons of using somatostatin analogs for acromegaly tx

Answer 26

Pros: - GH suppression - Possible tumor shrinkage Cons: - Majority of patients do not achieve IGF-1 normalization

Question 27

(GH/IGF-1) is associated with reduced morbidity (disease) and mortality (life expectancy)

Answer 27

IGF-1

Question 28

Acromegaly with un-normalized IGF-1 is associated with what morbidity conditions?

Answer 28

1. CVD (main cause of their death) 2. Colon cancer 3. Thyroid cancer 4. Diabetes Mellitus

Question 29

What is the method of choice for treating acromegaly?

Answer 29

Transsphenoidal adenomectomy * Medication if tumor is inoperable