ENDO

Question 1

Experimental rats undergo resection of the pituitary gland. The experimental animals are subsequently found to have decreased production of epinephrine by the adrenal medulla and cortisol from the adrenal cortex. Decreased activity of which enzyme is most likely responsible for the lower epinephrine in the experimental animals?

Answer 1

PNMT
Cortisol is produced in Adrenal cortex (zona Fasiculata) and is converted into EPINEPHRIN BY PNMT IN ADRENAL MEDULLA.However, following pituitary resection, the loss of ACTH leads to decreased synthesis of cortisol in the adrenal cortex. The result is decreased PNMT activity because cortisol upregulates PNMT.
Less PNMT activity means less Epinephrine formed in Medulla.

Question 2

VIPOMA arises in ________

Answer 2

Pancreas.

Vipoma—> WDHA (WADDA)—> Watery Diarrhea, Hypokalemia, Achlorhydria.

Question 3

How will a TBG deficiency manifest in a newborn?

Asked in NBME20

Answer 3

Decreased T3, T4.
But NORMAL TSH AND FREE T4.

Mnemonic is: Normal free.

Question 4

Riedel Thyroiditis is associated with which autoimmune condition?
(RIDDLES ARE HARD)

Answer 4

IgG4-related systemic disease (eg, autoimmune pancreatitis, retroperitoneal fibrosis, noninfectious aortitis)

Question 5

All of these conditions will present with HYPOCALCEMIA, which of the following condition will have hypophosphatemia as well?
Vitamin D deficiency
Hypoparathyroidism
2° hyperparathyroidism (CKD)
Pseudohypoparathyroidism 
Hyperphosphatemia

Answer 5

Vitamin D deficiency-CORRECT.
Vitamin D deficiency occurs in Celiac disease. And will show the following labs: (asked in uworld specifically)
>Low 25-OH Vitamin D
>ELEVATED PTH--> ELEVATED ALP
> Low serum phosphate and calcium!

Question 6

In which conditions, SHBG is increased or decreased?

What is the mechanism of conditions related to increase and decrease of SHBG?

Answer 6

SHBG is increased in—–> INCREASED estrogen in Cirrhosis, OCP use, Pregnancy, Hyperthyroidism.
SHBG is decreased in—> Exogenous androgens, Nephrotic Syndrome, Hypothyroidism.

So androgens bind to SHBG more than estrogen—>
In men, increased SHBG binds to testosterone more and then free estrogen levels in serum rise–> gynecomastia.

In decreased SHBG in females, less bound testosteron and more free testosterone means–> Hirsutism.

Question 7

MAP kinase pathway?

Answer 7

Growth factors that have a receptor tyrosine kinase. 
Insulin
PDGF
IGF-1
FGF
EGF

Question 8

What kind of receptors cause JAK/STAT pathway transduction?

Answer 8

Non-receptor Tyrosine kinase
(without a receptor—> they move haphazard or if I may say JAK/STAT!)
PIGG-L-ET (L is extra, just to complete the word)
Prolactin, Interleukins (2,6,interferon gamma), Growth hormone, G-CSF (filgrastim is a G-CSF analog), Erythropoietin, Thrombopoietin (stimulates megakaryocyte proliferation).

Question 9

What stimulates production of 1,25 OH vitamin D?

Answer 9

25-OH D3 is converted to 1,25-(OH)2D3 by 1 α-hydroxylase!

1α-hydroxylase is stimulated by REDUCED PHOSPHATE, INCREASED PTH.

Question 10

PTH-related peptide (PTHrP) is commonly increased in

malignancies such as _________________?

Answer 10

squamous cell carcinoma of the lung,

renal cell carcinoma

Question 11

Action of 1,25-(OH)2D3 on bone and gut?

You did this wrong on NBME

Answer 11

It functions to increase calcium and phosphate in serum so:

1. INCREASES Ca2+ and PO4 released from bone!
2. INCREASES absorption of Ca2+ and PO4!

Question 12

PTH affects on kidney?

Answer 12

decreased phosphate reabsorption in PCT

increased calcium reabsorption in DCT.