{"id":"8c4123b5-e118-5510-8581-137262825b79","stable_key":"434e1e27-eb90-583a-956b-62472726ffba:cal-carbonate-levothyroxine-absorption","predicate":"has_reported_effect_on","statement":"Simultaneous calcium carbonate reduced measured levothyroxine absorption in a seven-volunteer experiment.","claim_class":"observational","status":"source_derived_draft","evidence_grade":"ungraded","direction":"negative","is_public":true,"mechanism_event_id":"afd80940-c6f7-54cc-98b3-fd8bc683e74f","mechanism_event_label":"The tested calcium preparation reduced the medicine reaching circulation.","subject":{"id":"4ee1cbd0-1cec-58e1-9fee-bdb2c13db94d","slug":"calcium-carbonate","display_name":"Calcium carbonate","entity_type_key":"chemical_species"},"object":{"id":"ef8d6bed-42c5-5e78-8b97-73efcab6f4af","slug":"levothyroxine-absorption","display_name":"Levothyroxine absorption","entity_type_key":"cellular_process"},"evidence_count":1,"mechanism_event":{"id":"afd80940-c6f7-54cc-98b3-fd8bc683e74f","stable_key":"434e1e27-eb90-583a-956b-62472726ffba:cal-carbonate-levothyroxine-absorption-event","event_type":"observed_intervention","label":"The tested calcium preparation reduced the medicine reaching circulation.","description":"Simultaneous calcium carbonate reduced measured levothyroxine absorption in a seven-volunteer experiment.","status":"provisional","compartment":null,"participants":[{"entity":{"id":"4ee1cbd0-1cec-58e1-9fee-bdb2c13db94d","slug":"calcium-carbonate","display_name":"Calcium carbonate","entity_type_key":"chemical_species"},"role":"tested_input","stoichiometry":null,"state_label":"","sequence_order":0,"notes":""},{"entity":{"id":"ef8d6bed-42c5-5e78-8b97-73efcab6f4af","slug":"levothyroxine-absorption","display_name":"Levothyroxine absorption","entity_type_key":"cellular_process"},"role":"measured_outcome","stoichiometry":null,"state_label":"","sequence_order":1,"notes":""},{"entity":{"id":"f2b25f38-ec94-57d0-a46d-dd0fee45f01e","slug":"thyroxine","display_name":"T4","entity_type_key":"small_molecule"},"role":"coadministered_medicine","stoichiometry":null,"state_label":"","sequence_order":2,"notes":""}]},"contexts":[{"dimension":"experimental_model","value_text":"Two visits separated by four weeks; serum-based pharmacokinetic estimation.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"exposure","value_text":"1000 micrograms levothyroxine with or without 2 g elemental calcium as carbonate; six-hour total absorption differed (P=0.02).","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"limitations","value_text":"Small acute high-dose experiment, not individualized medicine instructions.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"nutrient_topic","value_text":"Calcium research collection; topical membership is not evidence of a direct dietary effect.","comparator":null,"unit":null,"notes":"","entity":{"slug":"calcium","display_name":"Calcium","entity_type_key":"nutrient_element"}},{"dimension":"organism","value_text":"Homo sapiens","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"plain_language","value_text":"The tested calcium preparation reduced the medicine reaching circulation.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"primary_references","value_text":"[cal-clin-singh2001] The acute effect of calcium carbonate on the intestinal absorption of levothyroxine (2001). https://pubmed.ncbi.nlm.nih.gov/11716045/ DOI: 10.1089/105072501753211046","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"tissue_or_cell_type","value_text":"Human clinical or absorption endpoint","comparator":null,"unit":null,"notes":"","entity":null}],"evidence":[{"id":"5605ed8f-c923-59ce-842b-749fae20d309","evidence_kind":"source_excerpt","locator":"Lines 1400-1410","start_line":1400,"end_line":1410,"excerpt":"### cal-carbonate-levothyroxine-absorption\nSimultaneous calcium carbonate reduced measured levothyroxine absorption in a seven-volunteer experiment.\nCondition category: normal\nnutrient_topic: Calcium research collection; topical membership is not evidence of a direct dietary effect.\nplain_language: The tested calcium preparation reduced the medicine reaching circulation.\norganism: Homo sapiens\ntissue_or_cell_type: Human clinical or absorption endpoint\nexperimental_model: Two visits separated by four weeks; serum-based pharmacokinetic estimation.\nlimitations: Small acute high-dose experiment, not individualized medicine instructions.\nexposure: 1000 micrograms levothyroxine with or without 2 g elemental calcium as carbonate; six-hour total absorption differed (P=0.02).\n[cal-clin-singh2001] The acute effect of calcium carbonate on the intestinal absorption of levothyroxine (2001). https://pubmed.ncbi.nlm.nih.gov/11716045/ DOI: 10.1089/105072501753211046","model_system":"Two visits separated by four weeks; serum-based pharmacokinetic estimation.","directness":"author_interpretation","verification_status":"source_derived_draft","notes":"Exact curation-document quotation, not publisher quotation. Study references: [cal-clin-singh2001] The acute effect of calcium carbonate on the intestinal absorption of levothyroxine (2001). https://pubmed.ncbi.nlm.nih.gov/11716045/ DOI: 10.1089/105072501753211046","relationship":"supports","weight":1.0,"link_notes":"","source":{"id":"3c083fa0-59c6-50e9-af42-678d0e3c1006","stable_key":"import-434e1e27-eb90-583a-956b-62472726ffba","title":"Calcium: mechanism-first literature curation (2026-09-17)","document_type":"imported_text","citation_label":"AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text.","file_path":"","sha256":"965c934d6b147f2b62f8d45ce6d7a87681a600bfe5c46a585b4704889afd3fc1","revision_id":"543ec48b-4f70-5197-9d76-f5a3c443664c","review_status":"unverified_draft","notes":""}}],"relations":[],"conflicts":[],"corrections":[],"research":null}