Fat soluble vitamins : Vit D [ part 2 ]

               ★Vitamin D★

👉 Solar vitamin

👉 In human skin : 7-Dehydrocholesterol, an intermediate in synthesis of cholesterol

👉Undergoes a nonenzymaticreaction on exposure to UVL yielding pre-vitamin D.

👉Cholecalciferolis formed  after further reaction over a period of hour and absorbed into bloodstream.

👉Maximum vitamin synthesis: 10AM –2PM

        🔰Dietary Sources🔰  

* Required only in individuals with limited exposure to sunlight

* Plant-D2/ Ergocalciferol

* Animal-D3/ Cholecalciferol

* Fatty fishLiver

* Egg yolk

* Milk-after fortification

* Cheese

* Butter

Formation of vit D & Active Vit D

      ★★Functions of vitamin D★★

* Maintain adequate plasma Ca level by

* ↑uptake of Ca by intestine

* Minimize excretion of Ca by kidney (stimulate reabsorption in distal renal tubule)

* Stimulate Ca mobilization from bone when necessary

* Regulate gene expression & cell differentiation

* Insulin secretion

* Synthesis & secretion of parathyroid & thyroid hormones

* Inhibit production of interleukins by activated T-lymphocytes & immunoglobulin by activated B-lymphocytes

* Differentiation of monocyte precursor cells

* Modulation of cell proliferation

                🔰Rickets🔰

👉 Rickets is the failure in mineralization of growing bone or osteoid tissue.

👉Types1. Nutritional rickets

* In vitamin D deficiency

* Bones of children are undermineralizedas a result of poor absorption of Ca

 * Treatment: Vitamin D

 👉2. Renal rickets

* In CRF-↓Ability to form active vitamin D

* Treatment: Active vitamin D

👉 3. Hypophosphatemicrickets (vitD resistant rickets)

* Defective tubular reabsorptionof PO₄

* Treatment: VitD analog + PO₄4. Vitamin D dependent rickets

* Defective tubular reabsorptionof HCO₃⁻, PO₄, Glucose & AA.

* Treatment: Highest dose of vitamin D

          ⏩⏩Osteomalacia⏪⏪

👉 In  adults

👉 Demineralization of preexisting bones

👉 as a result bone soften & osteoporosis occurs.

👉↑ Susceptibility to fracture.

👉 More incidence-persons in poor daylight

👉 Findings

* ↓ Serum Ca

* ↓ Serum PO₄

* ↑↑ Serum alkaline phosphatase

In the Next article we will discuss about Vit E.
Good Luck
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