Thyroid dyshormonogenesis

Thyroid dyshormonogenesis is a rare condition due to genetic defects in the synthesis of thyroid hormones.
It is due to either deficiency of thyroid enzymes, inability to concentrate, or ineffective binding.

Signs and symptoms

The symtptoms of this disease are:
Very Frequent

Decreased circulating thyroxine level
Elevated circulating TSH concentration

Frequent

Abnormality of epiphysis
Congenital hypothyroidism
Constipation
Delayed closure of the cranial suture.
Delay of proximal femoral epiphyseal ossification
Feeding difficulties
Goitre
Big posterior fontanelle
Neurodevelopmental problems
Neonatal jaundice
Umbilical hernia

Occasional

Abnormality of circulating thyroglobulin concentration
Slow heart rate
Saddle nose deformity
Edema of face
Decreased reflexes
Hypotonia
Hypothermia
Increase of radioactive iodine uptake
Mental handicap
Large tongue
Neonatal hyperbilirubinemia

Very Rare

Sensorineural hearing loss

Cause

This is due to inability to produce thyroid hormones due to congenital absence of peroxidase or dehalogenase enzymes

Types

One particular familial form is associated with sensorineural deafness.
OMIM includes the following:

Type	OMIM	Gene
Type 1		SLC5A5
Type 2A		TPO
Type 2B		SLC26A4
Type 3		TG
Type 4		IYD
Type 5		DUOXA2
Type 6		DUOX2

Diagnosis

Diagnosis can be made by elevated serum TSH level and low T4 or free T4 level. Thyroid dyshormonogenesis diagnosis is based on high radioactive iodine uptake of the thyroid gland followed by more than 90% release after sodium perchlorate administration. Thyroid dyshormonogenesis is diagnosed with a 50%-90% release after perchlorate administration, which can be confirmed by genetic testing.

Treatment

Levothyroxine is the treatment of choice, with the immediate goal of raising the serum T4 level above 130 nmol/L as quickly as possible; with these doses, serum TSH usually normalizes within 2–4 weeks. Frequent laboratory monitoring in infancy is essential to make sure of optimal neurocognitive outcome. Serum TSH and T4 should be measured every 1–2 months in the first 6 months of life, every 3 months between 6 months and 3 years of age, and 4 weeks after any dose change.