10/7- Case Conference 1: Pituitary and Hypothalamus

Question 1

Case 1)

• A 45-year-old man is referred to you for management of diabetes mellitus diagnosed during a recent admission for bilateral carpal tunnel release.
• Other past medical history includes HTN for 10 years
• On review of systems he describes arthralgias and fatigue as well as recent impotence, which he attributes to an increase in the dosage of his BP medicine.
• Shoe and ring sizes have increased in the past 5 years.
• On exam, he has a gravelly voice, broad nose, prominent jaw, thick palms and soles, skin tags on his trunk and guaiac positive stool.

What are you thinking/DDx?

Answer 1

Acromegaly

Question 2

What is a condition associated with acromegaly you would like to pursue?

Answer 2

Polyps (possible blood in stool)

Question 3

What is causing the problem in acromegaly?

Answer 3

Pituitary tumor secreting excess GH

Question 4

What questions would you ask to assess possible pituitary adenoma (ROS)?

Answer 4

Tumor mass effect

• Vision defects (expecting possible bitemporal hemianopia or double vision due to CN impingement)
• Rhinorrhea/nasal discharge
• Headaches

Question 5

What tests would you do for acromegaly?

Answer 5

• IGF-1 levels (random GH levels are not particularly useful for diagnosis)
• Glucose tolerance test if IGF-1 is inconclusive
• MRI to assess for pituitary tumor
• More?

Question 6

How is GH affected by glucose?

Answer 6

Glucose will inhibit GH

• Low glucose -> higher GH/release
• High glucose -> lower GH

Question 7

Treatments for acromegaly?

Answer 7

• Surgery (TSR)
• Somatostatin agonst: Octreotide
• GHRA (recep antagonist): Pegvisomant
• DA agonist: Cabergoline

Question 8

Case 2)

• 27 yo woman is referred for evaluation of amenorrhea
• She had menarche at age 13 with regular menses until 3 years ago when they became irregular.
• She is GOPO.
• Menstrual periods ceased entirely 1 year ago.
• Her gynecologist gave her Provera, which resulted in a 2-day period.
• Serum prolactin = 295 ng/ml.
• She has occasional headaches and mild acne
• Physical examination is normal; there is no galactorrhea or hirsutism

What are your thoughts/DDx?

What else would you like to know/do next?

Answer 8

General DDx:

• Need to rule out pregnancy (do a serum B-HCG)
• Anorexia
• Chest wall injury or breast invasion

High prolactin level DDx:

• Prolactinoma
• Stalk effect (except not very likely; doesn’t typically result in such drastic inhibition of DA/rise in prolactin)
• Hypothyroid (low T4 will promote TRH release, which can stimulate prolactin) (do a TSH/FT4)
• Psychiatric drugs that are DA antagonists
• Kidney disease (inability to clear prolactin)

Question 9

Expect a macroprolactinoma. What would you order for diagnosis?

Answer 9

• MRI
• Humphrey visual field testing (if abnormal, follow up treatment to verify improvement)

Question 10

How would you treat someone with (macro)prolactinoma?

Answer 10

First line is medical treatment (not surgery!)

DA agonists:

• Cabergoline (1-2x/week)
• Bromocriptine

Surgery only done if hemorrhage or significant neurological compromise (or quick resolution if woman is planning pregnancy)

Question 11

Case 3)

• 58-yo man comes to your office with his wife. You begin to take his medical history, but soon realize that all the answers are coming from the wife. The patient himself does little more than sit back in his chair with a pleasant but faintly exhausted expression.
• Tiredness is his main complaint. He was quite active until his early 50’s, working as a clerk in a company warehouse. Three years ago he had to quit his job because he lost all his energy.
• He has stopped driving because of a series of minor accidents (“can’t see cars coming up alongside me”).
• History also reveals that he has been impotent over the last 2-3 years, likes to be sitting or lying down as much as possible because of mild dizziness when he stands, and spends most of his time dozing in front of the TV.
• On systemic review the wife recalls that he complained of a very severe headache (“like a bomb going off in his head”) about 3 years ago - the pain lasted about 2 days and was treated as “migraine” in a local ER. He shaves only once in 2 weeks.

Exam: A slow but cooperative man.

• Appears curiously boyish and elderly at the same time. Sallow complexion. Fine wrinkles (“crow’s feet”) around the eyes. Very little facial hair. Thyroid impalpable. Bilateral gynecomastia. Slightly protuberant abdomen. Female escutcheon (pattern of pubic hair). Testes 8 cc bilaterally.
• Symmetrically decreased muscle tone and strength. Slow return of deep tendon reflexes. Poor at calculation and immediate recall.

What are the clues in this physical exam/DDx?

Answer 11

All of this points toward hypothyroidism

• Decreased cortisol?
• GH-deficiency?

Question 12

What labs/tests would you like?

Answer 12

• Pituitary panal (ACTH, prolactin, IGF-1, etc.)
• T4 levels
• ITT is the gold standard for hypothyroid (GH axis and hypothalamic-pituitary-adrenal axis)
• Induced hypoglycemia should bump up GH (lack thereof confirms deficiency)

Question 13

How should hypothyroid pt be treated/managed?

Answer 13

Supplement deficient hormones:

• Steroids*
• Thyroid hormone*
• Testosterone
• GH (case-by-case basis)
• *Always give steroids before thryoid hormone, b/c full dose of thyroid hormone can cause adrenal crisis*

Determine if tumor; concerned about possible growth

Question 14

Why do you measure T4 rather than TSH?

Answer 14

If T4 is low, TSH will be high

• TSH can be inappropriately normal (if T4 is low, TSH should be high)?