Endo: Pituitary Dysf 2

Question 1

Describe the HPA axis for FSH and LH

Answer 1

1. Hypothalamus releases GnRH
2. GnRH stimulates gonadotropes in anterior pituitary to release FSH, LH
3. FSH and LH stimulate gonads to release sex hormones

Question 2

When should you test a female’s LH, FSH, estradiol?

Answer 2

During the first 5 days of her cycle (follicular phase)

Question 3

What is the definition of hypogonadism?

Answer 3

Reduced hormone release from the gonads (ovaries/testes)

Question 4

A patient has hypogonadism and low FSH/LH.

Where is the problem.

Answer 4

The hypogonadism is being driven by the low FSH/LH

Problem is in the pituitary or hypothalamus (central)

Question 5

These are all symptoms of what?

• Hot flashes
• Decreased libido
• Breast atrophy
• Osteoporosis
• Vaginal dryness
• Amenorrhea

Answer 5

Hypogonadism in females!

same symptoms as menopause

Question 6

Reduced libido, erectile dysfunction, infertility, decreased muscle mass, testicular atrophy are all symptoms of __________

Answer 6

Hypogonadism in men

Question 7

What are the typical symptoms of gonadotropinoma?

Answer 7

Gonadotropinoma (pituitary tumor secreting FSH/LH) will be asymptomatic until mass effects occur

Question 8

Describe the HPA axis for thyroid

Answer 8

1. Hypothalamus secretes TRH
2. TRH stimulates thyrotropes in anterior pituitary to release TSH
3. TSH stimulates thyroid to release T3, T4

*Somatostatin also inhibits TSH release

Question 9

What are the T3/T4 and TSH levels in central hyperthyroidism?

Answer 9

T3/T4 elevated

TSH elevated

Question 10

How is T3 made?

Answer 10

5’ deiodinase converts T4 to T3 (5,4,3)

Question 11

What are the effects of T3? (6)

Answer 11

• Brain maturation
• Bone growth
• B-adrenergic stimulation
• Basal metabolic rate increased
• Blood sugar increased
• Breakdown of lipids is increased

Question 12

Symptoms of hyperthyroidism

• Body habitus 2
• GI 2
• Bones 1
• Neuro 2
• Repro 1
• Temp 1
• CV 2

Answer 12

• Body habitus: weight loss, goiter
• GI: diarrhea, increased appetite
• Bones: osteoporosis
• Neuro: tremor, hyperactive
• Repro: irregular menses
• Temp: heat intolerant
• CV: HTN, palpitations

Question 13

Symptoms of hypothyroidism

• Temp: 1
• Body habitus/skin: 4
• GI: 1
• Neuro: 2
• CV: 1
• Repro: 1

Answer 13

• Temp: cold intolerant
• Body habitus/skin: weight gain, dry skin, hair loss, edema
• GI: constipation
• Neuro: lethargy, delayed DTR’s
• CV: Bradycardia
• Repro: irregular menses

Question 14

Define hypopituitarism

Answer 14

Deficiency of 1+ pituitary hormones

Question 15

What is hypophysitis?

What cell type is most commonly involved?

What is one cause?

Answer 15

Hypophysitis is inflammation of pituitary

Usually lymphocytic

Side effect of antibody cancer therapy

Question 16

Define apoplexy

How is it diagnosed?

Answer 16

Sudden hemorrhage of pituitary gland

Diagnosed with MRI or CT

Question 17

What is empty sella syndrome?

Compare primary and secondary

Answer 17

Empty sella syndrome: sella turcica is mostly filled with CSF instead of pituitary

Primary: Herniation of arachnoid layer presses on pituitary and causes atrophy

Secondary: due to pituitary disease

Question 18

ADH deficiency is most commonly seen with which type of tumor?

Answer 18

Metastatic tumors (not pituitary adenomas)

Question 19

What are the hormone levels in central hypothyroidism?

Answer 19

Free T4 is low

TSH is normal or low (it should be very high in response to low T4, but it’s insufficient)

Question 20

ADH is released in response to ____________ (2)

This is sensed by ______________ (2)

Answer 20

ADH is released in response to increased plasma osmolality and hypovolemia

This is sensed by hypothalamic chemoreceptors and baroreceptors

Question 21

Effects of ADH binding to…

• V1:
• V2

Answer 21

Effects of ADH binding to…

• V1: vasoconstriction, platelet aggregation
• V2: aquaporin translocation in collecting duct -> increased water reuptake

Question 22

In SIADH, there is

• _____ water retention
• __volemic hyp__natremia
• hyp__tonic plasma
• urine osmolality ___ plasma osmolality

Answer 22

In SIADH, there is

• increased water retention
• euvolemic hyponatremia
• hypotonic plasma
• urine osmolality >> plasma osmolality

Question 23

Tx of SIADH

Mild/Moderate (4)

Severe (1)

Answer 23

• Mild/Moderate: Fluid restriction, salt tablets, diuretics, vaptans/demeclocyline
• Severe: Hypertonic saline

Question 24

With severe hyponatremia from chronic SIADH, should we correct the sodium quickly or slowly? Why?

Answer 24

Correct is SLOWLY (less than 12 mmol decrease in first 24 hrs)

Too rapid correction will cause central pontine myelinolysis

Question 25

A marathon runner comes into the ED with severe hyponatremia. Should we correct their sodium quickly or slowly?

Answer 25

Correct it quickly - it onset was quick, correction can be quick

Question 26

What is Diabetes Insipidus? What is the primary feature?

Answer 26

Diabetes Insipidus is insufficent ADH release by pituitary or insufficient renal response to ADH Pts have LOTS of dilute urine

Question 27

What drug is most responsible for diabetes insipidus?

Answer 27

Lithium

Question 28

Describe the triphasic response of ADH following trauma

Answer 28

1. Axon shock -\> decreased hormone release -\> diabetes insipidus 2. Axon degeneration -\> release of stored granules -\> SIADH 3. After axons degenerate and ADH stores are depleted, get permanent Diabetes Insipidus

Question 29

Is cerebral edema possible in hypo or hypernatremia?

Answer 29

Cerebral edema is a possible consequence of hyponatremia

Question 30

Tx of central and nephrogenic DI

Answer 30

* _Central DI:_ desmopressin * _Nephrogenic DI:_ NSAID, HCTX, amiloride

Question 31

Why are patients with SIADH euvolemic?

Answer 31

* Pts with SIADH have excess ADH, causing water retention * The body responds by decreasing the Renin-Agtn system * This leads to decreased sodium reabsorption (which worsens the hyponatremia and causes total body water to be normal)