Rare diseases · Sign or symptom
Abnormal pineal melatonin secretion
HP:0012689
What it means
An anomaly in the amount or timing of melatonin secretion by the pineal gland. Note that melatonin is also synthesized by multiple tissues outside of the pineal gland.
The rhythm of melatonin synthesized in and released from the pineal gland is characterized by a prominent nocturnal peak, which also contains temporal information that had originated in the suprachiasmatic nucleus. Strong reductions of circulating melatonin are also observed in numerous disorders and diseases, including Alzheimer's disease, various other neurological and stressful conditions, pain, cardiovascular diseases, cases of cancer, endocrine and metabolic disorders, in particular diabetes type 2.
Rare diseases that can present with this4
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. A sign on this page is a conversation to have with a clinician, not a conclusion.
Part of the broader category
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.