Chemistry - Osler: Pituitary, Gonads And Bones

Front 1

What stimulates prolactin?

Back 1

TRH, Dopamine antagonists

sleep, acute stress, sex, chest/nipple stimulation, pregnancy, seizures, antipsychotics

Front 2

What inhibits prolactin

Back 2

dopamine

chronic stress, chronic illness, malnutrition

Front 3

What are some causes of increased prolactin?

Back 3

Adenoma, pituitary stalk compression, H2 blocker, phenothiazines, TRH

Front 4

A prolactin level of >200 indicates what?

Back 4

A tumor

Front 5

An elevated prolactin but less than 100 ng/ml suggests what?

Back 5

A cause other than a tumor

Front 6

What stimulates the release of growth hormone? Inhibits?

Back 6

Stimulated by GHRH, inhibited by somatostatin. Also stimulated by sleep, acute stress, fasting, hypoglycemia

Front 7

How do we evaluate growth hormone production?

Back 7

Look at growth hormone levels and IGF-1 levels.

Growth hormones fluctuate, so IGF-1 (somatomedin) is a better test.

Front 8

Underproduction of GH causes?

Back 8

Rare cause of dwarfism

Front 9

Overproduction of GH?

Back 9

Gigantism or acromegaly

Front 10

What does LH regulate?

Back 10

wants to make hormones!

stimulates steroid synthesis

in females: androgens before ovulation and progesterone after ovulation

in males: testosterone

Front 11

What does FSH regulate?

Back 11

wants to make eggs and sperm!

stimulates development of follicles to prepare for ovulation. stimulates proliferation of germ cells to form sperm

Front 12

What stimulates gonadotropins?

Back 12

Cyclic GnRH, norepinephrine, light

Front 13

What do theca cells produce?

Back 13

LH converts cholesterol to androstenedione (hint: tHeca and LH both have H as the second letter in their name)

In fat, this is converted to testosterone

in granulosa cell, this is converted to estradiol by FSH

Front 14

How are estradiol and testosterone found in circulation?

Back 14

Bound to SHBG or albumin

Front 15

How does obesity affect SHBG levels?

Back 15

inhibits production

Front 16

What part of HCG is tested with the assay

Back 16

the beta subunit

Front 17

What are the 2 major physiologic causes of amenorrhea?

Back 17

Menopause - increased FSH (also increased LH).

pregnancy - increased HCG.

Front 18

What are causes of hirsutism?

Back 18

PCOS high LH FSH ratio
Cushing syndrome
CAH - high steroid precursors

familial - increased 5-alpha reductase

Front 19

How is extracellular calcium forms transported?

Back 19

Free 50%, protein bound 40%, complexed 10% (PO4, HCO3)

Front 20

How does PTH act?

Back 20

Acts on the bone to mobilize calcium from the osteocytes
Also acts on the kidneys to cause loss of the complexing ions increasing free calcium

Front 21

How is calcitriol produced?

Back 21

By the kidney, stimulated by PTH

Front 22

What does calcitriol do?

Back 22

It acts on the bone to increased mobilized CA. Acts on the intestinal tract and increases absorption, and then inhibits PTH production and it's own production.

Front 23

What level do you check for VIt D deficiency?

Back 23

25-hydroxy vitamin D

Front 24

Where is calcitonin produced?

Back 24

parafollicular C cells in thyroid, lung

Front 25

What is the function of calcitonin?

Back 25

Inhibits bone resorption, lowers serum calcium by increasing renal excretion of calcium and phosphate

Front 26

How does gadolinium affect calcium?

Back 26

Will lead to falsely low calcium results

Front 27

What is the halflife of PTH?

Back 27

3-5 minutes

Front 28

What are the three etiologies responsible for 99% of hypercalcemia cases?

Back 28

Hemoconcentration, Primary hyperparathyroidism, Maignancy

Front 29

How many hydroxyl groups in 25 OHD? 1,25 dihydroxy vitamin D? 7-dehyrdrocholesterol?

Back 29

2, 3 and 1, respectively

Front 30

Causes of hypocalcemia?

Back 30

Low albumin, renal failure
Uncommon - hypmagnesemia, malapsorption, vit D deficiency, Hypoparathyroidism, sepsis, shock, pancreatitis

Front 31

What are the labs seen in secondary hyperparathyroidism?

Back 31

PTH much higher than primary hyperpara
More severe bone disease
Due to chronic hypocalcemia
Often associated with high phoshate when due to renal failure

Front 32

What is seen in FHH? (Familial hypocalciuric hypercalcemia)

Back 32

Abnormal receptors which dont respond to calcium, leading to more pth and hypercalcemia
Decreased urine excretion of calcium

Front 33

what is macroprolactin?

Back 33

high molecular weight form bound either to IgG or prolactin receptor. 10% of people with increased prolactin have macroprolactin

Front 34

in hypopituitism, what order do you see hormones decrease usually?

Back 34

GH and gonadotropins early

TSH later

ACTH last

Front 35

which four hormones have a common alpha subunit and distinct beta subunits?

Back 35

TSH, HCG, FSH, LH

Front 36

how can you distinguish central and nephrogenic diabetes insipidus?

Back 36

after water deprivation test, give ADH.

central DI: urine concentration rises and volume falls

nephrogenic DI: no response

Front 37

when is testosterone highest?

Back 37

it is highest on rising and declines during the day.

morning testosterone declines slowly with older age and obesity

Front 38

what can be used to evaluate the function of the corpus luteum?

Back 38

progesterone. must be interpreted based on the day of the cycle

Front 39

what is AMH? what produces it?

Back 39

produced by granulosa cells, inhibits excess response to FSH. Declines as follicles are lost. Marker of ovarian reserve. High in PCOS and ovarian hyperstimulation.

Front 40

What are the HCG levels in the following:

ectopic pregnancy

threatened miscarriage

trophoblastic neoplasia

Back 40

ectopic pregnancy - slower rate of increase than normal and low for dates.

threatened miscarriage - low and falling results.

trophoblastic neoplasia - often high for dates, needed to follow treatment.

note: ectopic and trophoblastic neoplasia may have abnormal HCG forms not detected by some assays.

Front 41

how can DHEAS (dehydroepiandrosterone sulfate) and testosterone be used to determine source of increased androgens?

Back 41

ovarian: increased testosterone but not DHEAS

adrenal: increased DHEAS but not testosterone

Front 42

where is PTHrP produced and what does it do?

Back 42

produced by most cells but in greatest amounts by fetal parathyroid, squamous epithelial cells and breast epithelial cells.

It is involved in bone formation in fetus, calcium mobilization in the mother during pregnancy and lactation and transplacental transport of calcium.

Front 43

which form of vitamin D do you get from plants? sun?

Back 43

ergocalciferol - plants.

7-dehydrocholesterol - sun.

Front 44

what test do you do to measure total calcium? what are 2 interferences?

Back 44

colorimetric assay. Interferences include chelating agents such as EDTA and gadolinium

Front 45

how do you measure free calcium?

Back 45

ion selective electrodes

Front 46

what are 3 etiologies for hypercalcemia?

Back 46

hemoconcentration, primary hyperparathyroidism, and malignancy

Front 47

in sarcoid, there can be ectopic production of what?

Back 47

calcitroil

Front 48

what are two causes of secondary hyperparathyroidism?

Back 48

chronic renal failure and vitamin D deficiency

Front 49

what are four causes of hypoparathyroidism?

Back 49

hypoparathyroidism labs: low calcium and high phosphate.

causes: surgical removal of parathyroids, autoimmune destruction, DiGeorge syndrome and parathyroid infiltration (hemochromatosis)