AIIMS CRE, SNO-2024: Intracellular iron sequestration is performed by:

AIIMS CRE, SNO-2024

Biochemistry & Nutrition

Easy

Appeared in: AIIMS CRE, SNO-2024

Explanation

Ferritin is the primary intracellular protein for iron storage, safely sequestering iron to prevent cellular toxicity from free iron radicals.
It is a ubiquitous protein found in almost all cells, but especially in the liver, spleen, and bone marrow, which are major sites of iron storage.
Ferritin maintains iron in a soluble, non-toxic, and bioavailable form, ready to be mobilized when the body's iron needs increase.
Serum ferritin levels directly correlate with the body's total iron stores, making it a key diagnostic marker for iron-related disorders.

Option A: Transferrin is responsible for the transport of iron through the bloodstream, not for its storage within cells.
Option C: Hemoglobin's primary function is to transport oxygen in red blood cells. While it contains a large amount of the body's iron, it is a functional protein, not a storage protein.
Option D: Hemosiderin is an insoluble iron-storage complex that forms when ferritin stores are overloaded. It is considered a secondary or pathological form of iron storage, not the primary method of sequestration.

Visual 1: Diagram: Iron Metabolism Cycle. A flowchart showing iron absorption from the gut, transport in blood via transferrin, uptake by cells, storage as ferritin, utilization in hemoglobin, and recycling by macrophages. This visual would clarify the distinct roles of each protein.
Visual 2: Illustration: Ferritin Protein Structure. An image depicting the spherical shell of the ferritin protein with iron atoms stored inside, illustrating how it safely contains iron.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain The concept tested is the body's mechanism for storing iron at the cellular level, specifically identifying the primary protein responsible for this function as background academic context rather than a clinical decision trigger.
Assessing serum ferritin is a standard nursing practice to evaluate a patient's iron status. Low ferritin indicates iron deficiency anemia, while high ferritin can signal iron overload (hemochromatosis) or inflammation.
Nurses must understand that ferritin is an acute-phase reactant. In patients with chronic inflammation, infection, or liver disease, ferritin levels can be elevated even if the patient is iron deficient. This requires careful interpretation of lab results.
What if? If a patient with chronic kidney disease has low hemoglobin, a nurse would anticipate orders for iron studies, including ferritin. If ferritin is low, iron supplementation is needed before erythropoietin therapy will be effective, as red blood cell production requires adequate iron stores.

How to Approach the Question

First, break down the question. The key terms are 'Intracellular' (inside the cell) and 'iron sequestration' (storing or hiding iron).
Next, consider the function of each option provided.
Eliminate options with clearly different primary functions. Hemoglobin's main job is oxygen transport, and Transferrin's is iron transport in the blood. This leaves Ferritin and Hemosiderin.
Differentiate between the remaining two options. Both are involved in intracellular iron storage.
Recall or deduce that there must be a primary, regulated storage system and potentially a secondary or overflow system. Ferritin is the primary, soluble, and readily accessible storage protein.
Identify Hemosiderin as the insoluble, less accessible form that accumulates when ferritin capacity is exceeded. Therefore, Ferritin is the correct answer for primary sequestration.

Concept Tested & Keywords

Concept Tested: The concept tested is the body's mechanism for storing iron at the cellular level, specifically identifying the primary protein responsible for this function.
Stem keywords: Intracellular, iron, sequestration
Lead-in keywords: performed by