Endocrinology8-2

Question 1

Light microscopy of a liver biopsy shows: (1) spotty hepatocyte necrosis & (2) inflammatory cell infiltration. The sample was taken from a patient who had just returned from a trip to Mexico. What is the most likely diagnosis?

Answer 1

Hepatitis A

Hallmarks of acute viral Hepatitis: (1) hepatocye injury/”ballooning degeneration” (2) hepatocyte death/”bridging necrosis”

Recent travel to an endemic country + histological signs of acute viral hepatitis=Hep A

Question 2

What serum molecule(s) is believed to increase insulin resistance in overweight individuals?

Answer 2

1. Free fatty acids (FFA)
2. Triglycerides (TG)

Question 3

List two common causes of hyperosmotic volume contraction.

Answer 3

1. diabetes insipidus
2. profuse sweating

Question 4

Preferred acute treatment for diabetic ketoacidosis.

Answer 4

Regular insulin IV

Question 5

Diagnosis:
Your patient has N/V & abdominal pain. He is found to be hypotensive and tachycardic on physical exam. Urine analysis indicates ketones and glucose in the urine.

Answer 5

Diabetic ketoacidosis

This patient most likely has T1DM. Acute treatment is regular insulin.

Question 6

Diagnosis:

Glucagonoma

Answer 6

Markedly elevated glucagon levels

Question 7

Diagnosis:

Your patient is a 50-year-old male with a 6 month history of decreased libido and headaches. PE reveals: (1) bitermporal hemaniopsia & (2) ophthalmoplegia.

Answer 7

pituitary apoplexy (pituitary hemorrhage)

Often associated with a pre-existing adenoma (Prolactinoma: suggested by the headaches and decreased libido). The patients are a great risk for cardiovascular collapse due to adrenocortical deficiency. Treatement: glucocorticoids

Question 8

Clinical Manifestation:

Glucagonoma

Answer 8

1. Necrolytic migratory erythema: coalescing erythematous lesions, with bronze indurations in the center
2. Diabetes mellitus
3. Anemia

Question 9

Diagnosis:

Fine-needle aspiration cytology shows: (1) Numerous intranuclear inclusion bodies (2) intranuclear grooves & (3) cells with large nuclei and sparse, finely dispersed chromatin.

Answer 9

Papillary carcinoma

Papillary carcinoma is the most common type of thyroid cancer. Psammoma bodies may aslo be detected.

Question 10

Name that Drug!

Rapid-acting insulins (15 minutes until peak)
Short-acting insulin (30 minutes until peak)
intermediate acting insulin (4-12 hours until peak)
Long acting insulin (3-9 hours until peak)
insulin analog (No peak; lasts 24 hours)

Answer 10

Rapid-acting insulins: (1) Aspart (2) lispro (3) glulisine
Short-acting insulin: Regular insulin
Intermediate acting insulin: NPH
Long acting insulin: Detemir
Insulin analog: Glargine

Question 11

What is the most common genotype that causes Klinefelter syndrome?

Answer 11

47XXY

46XY/47XXY mosaicism & 48XXXY are possible but less common.

Question 12

Clinical Manifestation:

Klinefelter Syndrome

Answer 12

1. Primary testicular failure: (1) Small, firm testes, (2) azoospermia, (3)infertility, (4) testosterone deficiency, (5) increased FSH and LH (6) cryptorchidism
2. Eunuchoid body habitus: tall, sparse facial and body hair, gynecomastia, decreased muscle mass
3. Intellectual disability: most are mild or normal, my have psychosocial abnormalities (i.e. lack of insight, poor judgement)

Question 13

Age range at which a diagnosis of Klinefelter Syndrome is often made

Answer 13

Teenage years

Question 14

Pathogenesis:

Klinefelter Syndrome

Answer 14

meiotic non-disjunction during meiosis I

Question 15

Pathogenesis:

Secondary hyperparathyroidism due to ESRD

Answer 15

1. Renal dysfunction prevents the production of 1,25 vitamin D (active form)
2. In the absence of active vitamin D, the serum Ca2+ is low
3. In response to low serum Ca2+, PTH levels increase

Question 16

Where does the conversion from calicidiol (25VitD) to calcitriol (1,25VitD) occur?

Answer 16

Kidney

The kidneys are responsible for producing active vitamin D.

Question 17

How would you expect the hypothalamic-pituitary-gonadal axis to be affected by a prolactinoma in a male?

Answer 17

GnRH –> Decreased due to Prl
LH –> Decreased due to Prl decreasing the GnRH
Testosterone –> Decreased b/c there is no LH

Secreting prolactinomas inhibit the entire axis of GnRH-LH/FSH-sex hormones

Question 18

Clinical Manifestation:

Prolactinoma (Pituitary tumor) in a male

Answer 18

1. bitemporal hemianopsia
2. impotence

Often detected late because men do not experience galactorrhea or amenorrhea. Tumor is usually large.

Question 19

Clinical Manifestation:

Prolactinoma (Pituitary tumor) in a female of reproductive age

Answer 19

1. bitemporal hemianopsia
2. amenorrhea
3. galactorrhea
4. infertility (due to elevated Prl supressing GnRH)

Question 20

Clinical Manifestation:

Prolactinoma (Pituitary tumor) in a post-menopausal women

Answer 20

1. bitemporal hemianopsia
2. headaches

These women are already infertile and amenorrheic.

Question 21

How does anorexia affect the the HPA axis for gonadotropic hormones?

Answer 21

Axis becomes hypogonadotropic (Decrease in LH, FSH and Estradiol)

Question 22

Which GLUT transporter is the only transporter that is responsive to insulin concentrations?

Answer 22

GLUT-4

Question 23

Structure:

Location of GLUT-4 receptors

Answer 23

skeletal tissue and adipocytes

Question 24

Which domain of a GPCR contains 20 hydrophobic amino acids? What is the function of this domain?

Answer 24

The alpha-helical segments are the hydrophobic transmemebrane components of a GPCR. This domain integrates the GPCR into the cell membrane.

Question 25

Which anti-hyperlipidemic drugs increase the risk of gallstone precipitation when combined together?

Answer 25

Fibrates (gemfibrozil) and bile acid-binding resins (cholestyramine)

Question 26

What is the most effective lipid-lowering drug for primary and secondary prevention of cardiovascular events, regardless of baseline lipid levels?

Answer 26

HMG-CoA reductase inhibitors (statins)

Question 27

Diagnosis:

Nests of polygonal cells with Congo red-positive deposits

Answer 27

Medullary carcinoma of the thyroid gland

Medullary thyroid cancer arises from neoplastic parafollicular C-cells. The cells secrete calcitonin which forms extracellular amyloid deposits.

Question 28

What is the relationship between glucagon and insulin?

Answer 28

Insulin will decrease the secretion of glucagon.

Insulin brings glucose into the cells. This decreases the hypoglycemic message that stimulates glucagon secretion.

Question 29

How does glucagon affect ketone body production?

Answer 29

Glucagon stimulates (1) ketone body production. It also stimulates (2) glycogenolysis (3) gluconeogenesis & (4) lipolysis.

Question 30

What is the most important determinant of insulin resistance?

Answer 30

Visceral obesity/waist-to-hip ratio

Question 31

Mechanism of Action:

Finasteride

Answer 31

(5 alpha reductase inhibitor): Prevents the peripheral conversion of testosterone to dihydrotestosterone.

Finasteride can be used to treat (1) BPH & (2) androgenetic alopecia

Question 32

Clinical Manifestation:

Late-stage hemochromatosis/”bronze diabetes”

Answer 32

Classic triad: (1) skin hyperpigmentation (2) diabetes mellitus (3) hepatomegaly

Question 33

How does primary hyperparathyroidism manifest in the skeletal system?

Answer 33

It manifests as osteitis fibrosa cystica.

(1) bone pain (2) subperiosteal erosions (3) “salt-and-pepper” skull (4) brown tumor bone cyts

Question 34

Pathogenesis:

amenorrhea in a patient with anorexia nervosa

Answer 34

1. Patients eating disorder results in low body fat
2. low body fat causes pulsatile GnRH secretion to end
3. the pituitary is no longer stimulated to release FSH and LH
4. estrogen levels remain low

Question 35

Function:

Thiazolidinediones (TZDs)

Answer 35

lower blood glucose by decreasing insulin resistance

Question 36

Mechanism of action:

Thiazolidinediones (TZDs)

Answer 36

1. Activate PPAR-_
2. PPAR-_ alters the transcirption of genes that metabolize glucose and lipids (i.e. adiponectin)
3. glucose is lowered