EVERYTHING THE USMLE CAN ASK YOU ABOUT VITAMIN A

by / Tuesday, 01 March 2011 / Published in Biochemistry

Vitamin A:

– is a cofactor in PTH (Caclium and PO4 are always in opposite direction – is a PTH problem)

– helps in csf production

– epithelial cell maturation (vitamin a does this)

– night vision is the most unique function of vitamin A

– slight antioxidant

 

Deficiency:

– poor night visiion (test wont say explicity “night vision”)

– lowered csf production

– hypoparathyroidism

– failure of epithelial cells to mature

 

** knowing the most unique function is imperative to know because these are the things the usmle will test on.

**translocation 15;17 promyeloblastic leukemia, give vitamin A and cells mature to AML, allowing to live longer since promyeloblastic patients die fast, where AML lasts a bit longer.

** any disease wearing away at an organ, giving vitamin A can regenerate epithelium, no matter what cell is being worn away

** calcium and PTH direction in same direction, PO4 opposite

 

Vitamin A excess:

Рexcessive csf = pseudotumor cerebri (papilledema, headache) Рthis combo should always be suspect of increased ICP, always want to rule out a brain mass by doing a ct or mri.  if there is not a mass, check csf with LP

hyperparathyroidism = hypercalcemia (what are hypercalcemia sx: stones, moans, groans, bones)

 

Pseudotumor cerebri:

main sign – papilledema

main symptom – headache

1st evaluating tool – ct scan will show enlargement of ventricles

managment Рstop vitamin a administration  + serial lumbar punctures

Main complication of P. Cerebri is blindness.

 

** NOTE: this is the only time when an increase in ICP is not worrisome of a herniating condition.  Only 30cc because any more will cause an osmotic shift

 

2 Responses to “EVERYTHING THE USMLE CAN ASK YOU ABOUT VITAMIN A”

  1. Cynthia says : Reply

    I really liked this material. Is this found in the USMLE Bible?

    • Jeff Anderson, MD says : Reply

      Hi Cynthia, yes everything on the site is found in the USMLE Bibles as well as our Live Step 1 course. Hope that helps!

      Paul

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