A one-year-old child presented to the OPD with the history of short stature, tiredness and constipation. Examination revealed a palpable goiter. Serum T4 was decreased and TSH levels were increased. Which is the most probable diagnosis?

1. A

   Thyroid dysgenesis

2. B

   Thyroid dyshormonogenesis

3. C

   TSH receptor blocking antibody

4. D

   Central hypothyroidism

Appeared in: OSSSC Nursing Officer-2023

Explanation

• The patient's signs (short stature, tiredness, constipation) and lab results (low T4, high TSH) confirm primary hypothyroidism.
• Thyroid dyshormonogenesis is an inborn error of thyroid hormone synthesis.
• The low hormone levels trigger the pituitary to release excess TSH.
• Constant TSH stimulation causes the thyroid gland to enlarge, resulting in a goiter.
• The presence of a goiter in primary hypothyroidism strongly points towards a synthesis defect (dyshormonogenesis).

Why Other Options Were Wrong

• Option A: Thyroid dysgenesis involves an anatomically abnormal (absent, small, or ectopic) thyroid gland. Therefore, a goiter would not be present.
• Option C: These antibodies block TSH from stimulating the thyroid gland, which would lead to thyroid atrophy (a small gland), not a goiter.
• Option D: Central hypothyroidism is characterized by low or inappropriately normal TSH levels because the primary defect is in the pituitary or hypothalamus. The patient has high TSH.

Related Visual

Clinical Relevance

• Nursing practice connection: Use the key finding related to Differential diagnosis of congenital hypothyroidism based on clinical and laboratory findings to guide bedside assessment, documentation, and the next nursing action.
• Early diagnosis and treatment of congenital hypothyroidism are critical to prevent irreversible intellectual disability (cretinism).
• Newborn screening programs are essential for detecting congenital hypothyroidism before clinical symptoms become apparent.
• Management involves lifelong thyroid hormone replacement with levothyroxine, with dose adjustments based on regular monitoring of growth, development, and thyroid function tests (TSH and free T4).

How to Approach the Question

• First, identify the core clinical problem from the patient's symptoms (short stature, tiredness, constipation), which are classic for hypothyroidism.
• Next, interpret the laboratory results. Low T4 confirms hypothyroidism. High TSH indicates the problem is in the thyroid gland itself (primary hypothyroidism), as the pituitary is trying to compensate.
• Then, focus on the key physical finding: the palpable goiter. A goiter is an enlarged thyroid gland.
• Correlate the findings. In primary hypothyroidism, a goiter means the thyroid gland is present but unable to produce hormones correctly, despite being heavily stimulated by TSH. This points to a functional defect (synthesis problem).
• Evaluate the options: Thyroid dysgenesis (anatomical defect, no goiter), TSH receptor blocking antibodies (atrophy, no goiter), and central hypothyroidism (low TSH) are all inconsistent with the finding of a goiter and high TSH. Thyroid dyshormonogenesis (synthesis defect) perfectly explains the combination of primary hypothyroidism and a goiter.

Concept Tested & Keywords

• Concept Tested: Differential diagnosis of congenital hypothyroidism based on clinical and laboratory findings.
• Stem keywords: one-year-old child, short stature, tiredness, constipation, palpable goiter, decreased T4, increased TSH
• Lead-in keywords: most probable diagnosis
• Clinical cues: The combination of primary hypothyroidism (low T4, high TSH) and a goiter is the key to differentiating the cause.

Question ID

Q05CCCIBtkDZsmPY1yHate

Copy ID

Reference Book

E6 Ghai Essential Pediatrics(pp 26-904 of 913) p. 538-540

E6 Nelson Textbook of Pediatrics(2024) — Volume 2 p. 1209-1211

E6 Medicine Davidson Principles Practice 24e p. 670-672