title: Severe hypercalcemia after transition from calcium carbonate to calcium citrate in an elderly woman treated with ergocalciferol 50,000 IU per day.
abstract: BACKGROUND
  Absorption of calcium carbonate in the fasting state has been reported to be significantly compromised in subjects with achlorhydria. Although calcium carbonate malabsorption in the fasting state cannot be predicted, it might be corrected if the compound is administered with meals. However, administering calcium carbonate with meals is logistically challenging in long-term care facilities.
  
  
  OBJECTIVE
  The aim of this study was to report the case of a woman who was transitioned to calcium citrate and subsequently experienced symptomatic severe hypercalcemia.
  
  
  METHODS
  An 89-year-old female resident of the Wisconsin Veterans Home, a skilled nursing facility in King, Wisconsin, was receiving long-term treatment with ergocalciferol (vitamin D2) 50,000 IU/d. The patient also was receiving calcium carbonate supplements in the morning, and she rarely ate breakfast (fasting state). The patient was transitioned from 2000 mg/d of elemental calcium as carbonate to 1230 mg/d as citrate.
  
  
  RESULTS
  After being switched from calcium carbonate to calcium citrate, the patient developed severe symptomatic hypercalcemia (16.8 mg/dL), the primary cause of which was the administration of an inappropriately high dose of vitamin D.
  
  
  CONCLUSIONS
  We report a case of symptomatic severe hypercalcemia in a skilled nursing facility resident treated with an inappropriately high daily dose of vitamin D. Hypercalcemia manifested when calcium carbonate was replaced with calcium citrate.
authors.affiliation: Wisconsin Veterans Home, King 54946-0620, USA. Paul.Drinka@dva.state.wi.us
authors.forename: Paul J
authors.initials: PJ
authors.lastname: Drinka
authors.forename: Jackie
authors.initials: J
authors.lastname: Moore
authors.forename: Michael C
authors.initials: MC
authors.lastname: Boushon
mesh_terms: D000369:Aged, 80 and over; D002119:Calcium Carbonate / Q000008:administration & dosage*; D019355:Calcium Citrate / Q000008:administration & dosage / Q000009:adverse effects*; D004872:Ergocalciferols / Q000008:administration & dosage* / Q000009:adverse effects*; D005215:Fasting; D005260:Female; D006707:Homes for the Aged; D006801:Humans; D006934:Hypercalcemia / Q000139:chemically induced*; D012866:Skilled Nursing Facilities; D014815:Vitamins / Q000008:administration & dosage / Q000009:adverse effects*
chemical_list: D004872:Ergocalciferols; D014815:Vitamins; D002119:Calcium Carbonate; D019355:Calcium Citrate