Which vitamin is regarded as kidney hormone?

RUHS, Jaipur, PB B.Sc Nursing Entrance-2022

Applied Nutrition & Dietetics

Medium

Appeared in: RUHS, Jaipur, PB B.Sc Nursing Entrance-2022

Explanation

Vitamin D is unique among vitamins because it functions as a prohormone.
It is obtained from the diet or synthesized in the skin but is biologically inactive in these forms.
The final and critical activation step occurs in the kidneys, where it is converted into its active hormonal form, 1,25-dihydroxyvitamin D (calcitriol).
Calcitriol is a steroid hormone that circulates in the blood to regulate calcium and phosphate levels by acting on the intestines, bones, and parathyroid glands.

Option A: Vitamin A (retinol) is a fat-soluble vitamin essential for vision, immune function, and epithelial cell integrity. It does not undergo activation in the kidney to become a hormone.
Option B: Vitamin C (ascorbic acid) is a water-soluble vitamin that functions as an important antioxidant and is required for collagen synthesis. It does not have hormonal properties.
Option D: Vitamin E (tocopherol) is a fat-soluble vitamin that primarily acts as an antioxidant, protecting cell membranes from oxidative damage. It is not classified as a hormone.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Hormonal function of Vitamin D and the endocrine role of the kidney as background academic context rather than a clinical decision trigger.
In Chronic Kidney Disease (CKD), the kidneys' ability to activate Vitamin D is progressively lost. This is a major cause of mineral and bone disorders in CKD patients.
Nurses caring for CKD patients must monitor calcium, phosphorus, and PTH levels and administer prescribed active Vitamin D analogs (like calcitriol) to prevent renal osteodystrophy.
Patient education should include the difference between nutritional Vitamin D (cholecalciferol) and active Vitamin D (calcitriol), explaining why the latter is needed when kidney function fails.

How to Approach the Question

First, analyze the core of the question, which is to identify a vitamin that acts as a 'kidney hormone'.
The term 'hormone' implies a substance produced in one part of the body that travels to and acts on another part.
The qualifier 'kidney' suggests the kidney is the site of production or activation.
Review the functions of the listed vitamins. Recall that most vitamins are essential nutrients obtained from the diet and cannot be synthesized by the body.
Consider the metabolic pathway of Vitamin D. Remember that it can be synthesized in the skin but requires activation. The final, crucial activation step to its hormonal form (calcitriol) happens in the kidney.
This unique two-step activation process, with the final step in the kidney, distinguishes Vitamin D from other vitamins and fits the description of a 'kidney hormone'.

Concept Tested & Keywords

Concept Tested: Hormonal function of Vitamin D and the endocrine role of the kidney.
Stem keywords: vitamin, kidney hormone
Lead-in keywords: Which
Negative lead-in flag: false

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E6 Parks TextBook of Preventive & Social Medicine part 2 — Subpart A (pp 1-232 of 464) p. 151-153

E6 Medicine Harrison 22e Part 2 p. 1172-1174