title: Impact of an Intravenous Magnesium Shortage on Potassium Doses in Adult Surgical Patients Receiving Parenteral Nutrition.
abstract: Shortages of parenteral nutrition (PN) components have been common in recent years. Effects on patient management and outcomes have not been well documented. This study aimed to determine the effect of a parenteral magnesium shortage, and an institutional decision to omit magnesium from adult PN, on magnesium and potassium doses and serum concentrations.
  
  
  
  This was a retrospective cohort study of adult surgical patients during two 6-month periods: prior to the magnesium shortage (2011) and during the shortage (2012). The relation between study period and electrolyte doses was evaluated by unadjusted and adjusted mixed models, while the relation between study period and hypokalemia and hypomagnesemia exposure was evaluated by Student's t tests and multiple linear regression.
  
  
  
  During the shortage, patients received more supplemental magnesium (0.11-0.12 mEq/kg/d, P < .0001) but received less total daily magnesium (0.08-0.09 mEq/kg/d, P < .0001) and had greater exposure to hypomagnesemia (9.6-14.2 h·mcg/dL/h, P < .05 for all comparisons except multivariate analysis in a matched subpopulation). Patients received similar amounts of potassium in PN (0.06-0.08 mEq/kg/d less, P < .05 for full cohort but P > .05 for matched cohort), in supplemental doses (0.01-0.05 mEq/kg/d less, P > .05), and in total (0.07-0.14 mEq/kg/d less, P > .05), and they had similar exposure to hypokalemia.
  
  
  
  Daily magnesium doses were lower and hypomagnesemia exposure was greater during the shortage, but the differences were numerically small and their clinical significance was questionable. Potassium doses and hypokalemia exposure were not higher during the shortage. This supports the strategy of omitting magnesium from PN of select patients and supplementing as clinically necessary.
authors: Department of Pharmacy, University of Michigan Health System, Ann Arbor, Michigan.
authors: Lisa A
authors: LA
authors: Scherkenbach
authors: Department of Pharmacy, University of Michigan Health System, Ann Arbor, Michigan College of Pharmacy, University of Michigan, Ann Arbor, Michigan.
authors: Michael D
authors: MD
authors: Kraft
authors: Metabolism, Interactions & Genomics Group, Wolters Kluwer Health/Clinical Solutions, Hudson, Ohio.
authors: Stephen M
authors: SM
authors: Stout
authors: Department of Pharmacy, University of Michigan Health System, Ann Arbor, Michigan College of Pharmacy, University of Michigan, Ann Arbor, Michigan.
authors: Michael P
authors: MP
authors: Dorsch
authors: College of Pharmacy, University of Michigan, Ann Arbor, Michigan.
authors: Xinwei
authors: X
authors: Chen
authors: College of Pharmacy, University of Michigan, Ann Arbor, Michigan.
authors: Hong-Diem
authors: HD
authors: Tran
authors: Department of Pharmacy, University of Michigan Health System, Ann Arbor, Michigan College of Pharmacy, University of Michigan, Ann Arbor, Michigan mpleva@med.umich.edu.
authors: Melissa R
authors: MR
authors: Pleva
mesh_terms: D000328:Adult; D000368:Aged; D015331:Cohort Studies; D005260:Female; D006801:Humans; D007008:Hypokalemia / Q000453:epidemiology; D008274:Magnesium / Q000008:administration & dosage* / Q000097:blood / Q000600:supply & distribution*; D008275:Magnesium Deficiency / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D010288:Parenteral Nutrition; D019990:Perioperative Care / Q000379:methods*; D011188:Potassium / Q000008:administration & dosage* / Q000097:blood; D012189:Retrospective Studies
chemical_list: D008274:Magnesium; D011188:Potassium
keywords: parenteral formulas/compounding; parenteral nutrition