Rare diseases · Sign or symptom
Hypothyroidism
Underactive thyroid
HP:0000821
What it means
Deficiency of thyroid hormone.
In everyday care
Most people with this sign do not have a rare disease — it appears in common conditions far more often. These general reference pages cover the same topic:
Rare diseases that can present with this131
Very common80–99%
13- Athyreosis
- Bangstad syndrome
- Blepharophimosis-intellectual disability syndrome, SBBYS type
- Cystinosis
- Dahlberg-Borer-Newcomer syndrome
- Fucosidosis
- Hypohidrotic ectodermal dysplasia-hypothyroidism-ciliary dyskinesia syndrome
- Jung syndrome
- Methimazole embryofetopathy
- Muscular pseudohypertrophy-hypothyroidism syndrome
- Thyroid ectopia
- Thyroid hypoplasia
- Woodhouse-Sakati syndrome
Common30–79%
15- Ascher syndrome
- Deafness-intellectual disability syndrome, Martin-Probst type
- Fetal iodine syndrome
- GNE myopathy
- IgG4-related thyroid disease
- Maternal uniparental disomy of chromosome 2 syndrome
- Mitochondrial DNA-related progressive external ophthalmoplegia
- Pendred syndrome
- Pituitary stalk interruption syndrome
- POEMS syndrome
- Short stature-craniofacial anomalies-genital hypoplasia syndrome
- Steroid-responsive encephalopathy associated with autoimmune thyroiditis
- Syndromic multisystem autoimmune disease due to Itch deficiency
- Thyroid lymphoma
- Trichomegaly-retina pigmentary degeneration-dwarfism syndrome
Sometimes5–29%
52- 14q11.2microduplication syndrome
- 19p13.12microdeletion syndrome
- 1p36deletion syndrome
- 22q11.2deletion syndrome
- 3-methylglutaconic aciduria-neonatal cataract-neurologic involvement-congenital neutropenia syndrome
- 45,X/46,XY mixed gonadal dysgenesis
- Acetazolamide-responsive myotonia
- Acquired aneurysmal subarachnoid hemorrhage
and 44 more in this range
The range is how often this sign appears among people diagnosed with each disease — it is not a probability of having any of them. Many of these signs also occur in common, non-rare conditions, and Orphanet separately records 1 disease where this sign is specifically absent. A sign on this page is a conversation to have with a clinician, not a conclusion.
Part of the broader category
Also called: Low T4
Tracking symptoms like this for someone? Eleplan keeps symptoms, diagnoses, medications and every specialist in one plan.
Start free with EleplanThis page uses the Human Phenotype Ontology (2026-06-23) — Human Phenotype Ontology Consortium, hpo.jax.org. Disease associations from Orphanet (INSERM), CC BY 4.0. Content is educational and is not medical advice.