The Question is from neet-zoology chemical-coordincation-and-integration , and it was created by the author T SAILAJA

Question

A rare genetic disorder affects the synthesis of a specific enzyme crucial for converting T4 to T3. Which of the following would be the MOST likely clinical presentation in a patient with this disorder?

T SAILAJA · Accepted Answer

## CORE INFORMATION
✓ **Answer**: [Option C]
## CONCEPT FRAMEWORK
	**Primary Concept**: Thyroid hormone metabolism
	**Related Topics**: Hypothyroidism, Thyroid function tests
	**Prerequisites**: Understanding of T4 and T3 roles in metabolism, thyroid hormone feedback regulation
## SOLUTION PATHWAY
**Given Information**:
		- The disorder affects an enzyme that converts T4 (thyroxine) to T3 (triiodothyronine).
		- T4 is a prohormone that is converted to the more active T3 in peripheral tissues.
**Method & Steps**:
	1.	Identify the consequences of impaired conversion of T4 to T3.
		Reasoning: Since T3 is the active form, a decrease in T3 levels will result from this disorder.
		Formula/Rule: T3 = f(T4, conversion enzyme)
	2.	Consider the feedback mechanism involving TSH (Thyroid Stimulating Hormone).
		Working: Decreased T3 levels will lead to a lack of negative feedback on the pituitary gland, resulting in increased TSH production.
		Key Point: Elevated TSH is a response to low T3 levels.
	3.	Conclude the expected laboratory findings.
		Result: Elevated TSH levels and decreased T3 levels due to the disorder.
		Verification: Confirm against normal physiology where T3 levels regulate TSH secretion.
## OPTION ANALYSIS
[A] :x: Elevated TSH and T3 levels: This option contradicts the expected decrease in T3 due to the disorder.
[B] :x: Decreased TSH and T3 levels: This does not align with the expected increased TSH due to low T3 levels.
[C] ✓: Elevated TSH levels and decreased T3 levels: Correct as TSH would increase in response to low T3.
[D] :x: Decreased TSH and elevated T3 levels: Also incorrect as T3 would not be elevated in this disorder.
## LEARNING AIDS
	**Common Mistakes**:
		1. Confusing T4 and T3: Remember, T3 is the active hormone, and T4 is converted into T3.
		2. Misunderstanding feedback loops: Review how thyroid hormone levels affect TSH secretion.
	**Quick Tips**:
		1. Remember the relationship: Low T3 leads to high TSH.
		2. Use mnemonics to recall hormone functions: 'T3 is the active key, T4 is the prohormone sea.'

T SAILAJA · Answer

Elevated TSH and T3 levels

T SAILAJA · Answer

Decreased TSH and T3 levels

T SAILAJA · Answer

The correct Option is "Elevated TSH levels and decreased T3 levels"

T SAILAJA · Answer

Decreased TSH and elevated T3 levels

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