Hypothyroidism due to dysfunction of the hypothalamus, assumed to result in reduced secretion of thyrotropin- releasing hormone. The disease is isolated thyrotropin-releasing hormone deficiency (Monarch Disease Ontology id MONDO_0010140). Also known as: isolated TRF deficiency, isolated TRH deficiency, isolated TSH-releasing factor deficiency, isolated prothyroliberin deficiency, isolated protirelin deficiency, isolated thyroliberin deficiency, isolated thyrotropin-releasing factor deficiency, tertiary hypothyroidism.