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 : Vitamin A 

Vitamin A is a subclass of a family of lipid-soluble compounds referred to as retinoic acids.There are two main forms of vitamin A: provitamin A carotenoids which can be found in plants source of food like green leafy vegetables, sweet potatoes, and carrots, and Preformed vitamin A (retinol, retinal, retinoic acid, and retinyl esters) is the most active form of vitamin A, it is mostly found in animal sources of food like liver, kidney, egg yolk, and butterand is also the form supplied  by most supplements. Some supplements provide a combination of provitamin A (beta-carotene) and preformed vitamin A
serum vitamin A normal range is (15-60 ) microgram/dl and it vareis slightly in different labs , but we dont use serum vitamin A to measure defeincy that it doesnt reflect the total vitamen A stores under certain condition so we depend more  in clincal manifstation and serum retinol levels to be less 20 micorgram/dl to concider defiency
  :Clinical manifestations 
Xerophthalmia(pathologic dryness of the conjunctiva and cornea)
Poor bone growth
Nonspecific dermatologic problems, such as hyperkeratosis, phrynoderma
Impairment of the humoral and cell mediated immune system

 : Actions

Vision : In the eye, vitamin A has two major roles, prevention of xerophthalmia (abnormalities in corneal and conjunctival development) and phototransduction
 .Cellular differentiation
 : Recommendations
To visit your doctor to determine deficiency and start mangment if required