Congenital hypothyroidism due to maternal intake of antithyroid drugs

What it is

From: Orphanet

A rare congenital hypothyroidism disorder characterized by transient, primary, fetal or neonatal hypothyroidism resulting from transplacental transfer of antithyroid drugs due to maternal intake. Patients may present fetal or neonatal goiter, hoarse cry, reduced tendon reflexes, feeding difficulty, constipation, prolonged jaundice and/or respiratory distress. Elevated levels of T4 and thyroid stimulating hormone usually normalize without treatment within 3 weeks of birth.

Reported clinical features and what the terms mean

The following findings are associated with this condition in Orphanet. They are not a checklist for diagnosing yourself, and they do not all occur in every affected person. Some are examination, imaging or laboratory findings that cannot be recognised at home.

The frequency labels describe how often a finding was reported among people with the condition in the source. They do not give the chance that a person with that symptom has the condition. Definitions below reproduce HPO terminology; they explain the term, not the likely severity in an individual.

Abdominal distention · Very frequent (99-80%)

Distention of the abdomen.

Congenital hypothyroidism · Very frequent (99-80%)

A type of hypothyroidism with congenital onset.

Decreased circulating thyroxine level · Very frequent (99-80%)

A reduction below the normal concentration of thyroxine in the blood. Thyroxine (also known as T4) is the main hormone secreted by the thyroid gland into the blood. It can be converted into the active form triiodothyronine (also known as T3).

Elevated circulating thyroid-stimulating hormone concentration · Very frequent (99-80%)

Increased concentration of thyroid-stimulating hormone (TSH) in the blood circulation.

Goiter · Very frequent (99-80%)

An enlargement of the thyroid gland.

Abnormality of epiphysis morphology · Frequent (79-30%)

An anomaly of epiphysis, which is the expanded articular end of a long bone that developes from a secondary ossification center, and which during the period of growth is either entirely cartilaginous or is separated from the shaft by a cartilaginous disk.

Absent ossification of capital femoral epiphysis · Frequent (79-30%)

Lack of ossification of the proximal epiphysis of the femur.

Constipation · Frequent (79-30%)

Infrequent or difficult evacuation of feces.

Depressed nasal bridge · Frequent (79-30%)

Posterior positioning of the nasal root in relation to the overall facial profile for age.

Feeding difficulties in infancy · Frequent (79-30%)

Impaired feeding performance of an infant as manifested by difficulties such as weak and ineffective sucking, brief bursts of sucking, and falling asleep during sucking. There may be difficulties with chewing or maintaining attention.

Hyporeflexia · Frequent (79-30%)

Reduction of neurologic reflexes such as the knee-jerk reaction.

Hypothermia · Frequent (79-30%)

Reduced body temperature due to failed thermoregulation.

Large for gestational age · Frequent (79-30%)

The term large for gestational age applies to babies whose birth weight lies above the 90th percentile for that gestational age.

Macroglossia · Frequent (79-30%)

Increased length and width of the tongue.

Other findings in the same source

From: Orphanet

Additional reported features include Moon facies (Frequent (79-30%)); Mottled pigmentation (Frequent (79-30%)); Neonatal hypotonia (Frequent (79-30%)); Prolonged neonatal jaundice (Frequent (79-30%)); Protuberant abdomen (Frequent (79-30%)); Umbilical hernia (Frequent (79-30%)); Delayed epiphyseal ossification (Frequent (79-30%)); Hypersomnia (Frequent (79-30%)); Bradycardia (Occasional (29-5%)); Dry skin (Occasional (29-5%)). This is a selected summary, not a complete description of the condition.

When it may begin

From: Orphanet

Infancy; Neonatal

Which doctor should you see?

The suggested department for discussing Congenital hypothyroidism due to maternal intake of antithyroid drugs is Endocrinology, with a endocrinologist as the relevant type of clinician. General physician / Family Medicine; paediatrician for children. Referral depends on symptoms.

This is an editorial referral starting point. The appropriate clinic depends on the person’s age, symptoms, previous diagnosis and local services. The first clinician can decide whether another specialty or a team is needed; a department label does not confirm the diagnosis.

How to prepare for an assessment

Bring a short timeline of the main symptoms: when they first appeared, whether they are constant or episodic, what seems to change them, and how they affect daily activities. Include previous reports, discharge summaries, current medicines and supplements, allergies, and any relevant family history. A dated record is more useful than trying to match every feature in an online article.

Ask the clinician what is already established and what remains uncertain. If a test is suggested, ask what question it answers, what its limitations are and how the result would change the next step. The information here is not an instruction to arrange every possible test. In children, bring growth, developmental and school information if it is relevant to the concern.

• Which hormone or metabolic finding is important in this case?
• How should test timing and current medicines be taken into account?
• What follow-up would show whether the care plan is working?

Treatment discussions and follow-up

Where the source describes treatments, these are an overview of possible care, not a prescription for an individual. Ask which option applies to the confirmed diagnosis, what benefit is expected, what adverse effects to watch for and how progress will be assessed. Availability, approvals and local practice can differ from the country described in the source.

Before leaving the appointment, clarify the next review date, who will communicate results, and whom to contact if the situation changes. Discuss difficulties with sleep, work, school, mobility, eating or emotional wellbeing when these are relevant. Practical support may require coordination between the treating clinician and other services.

The collected references do not establish a complete prevention or long-term outlook section for this entry. Missing information should not be interpreted as proof that prevention is impossible or that a particular outcome is inevitable. Ask what is known for the exact subtype, stage and personal circumstances, and which uncertainties remain.

When to seek emergency help

Severe breathing difficulty, collapse, new stroke-like symptoms, a seizure that is prolonged or repeated without recovery, uncontrolled major bleeding, or an immediate risk of self-harm require emergency help. In India, call 112 or reach the nearest emergency department. This is a general, non-exhaustive warning list; it is not a condition-specific triage tool.