title: New-onset hyponatraemia after surgery for traumatic hip fracture.
abstract: BACKGROUND
  hyponatraemia in orthopaedic patients is common but has been poorly investigated following surgery for traumatic hip fracture. The aims of this study were to define the incidence of new-onset post-operative hyponatraemia and to investigate associations between hyponatraemia and patient demographics, medication use and duration of hospital stay.
  
  
  METHODS
  all patients admitted to the Orthopaedic Unit for hip surgery following trauma in 2012 were retrospectively reviewed. Patients who developed post-operative hyponatraemia within 10 days of surgery were compared with patients who remained normonatraemic pre- and post-operatively.
  
  
  RESULTS
  a total of 254 patients were included. Overall, this study identified a significant (P =< 0.001) mean post-operative drop in serum sodium of 1.8 mmol/l (95% CI: 1.3-2.3%) compared with pre-operative levels. The incidence of moderate (<135 mmol/l) and severe (<130 mmol/l) post-operative hyponatraemia was 27% (95% CI: 21.7-32.5%) and 9% (95% CI: 5.7-12.8%), respectively. Statistical analysis revealed significant associations between the development of post-operative hyponatraemia and: (i) proton pump inhibitor use, (ii) selective serotonin re-uptake inhibitor use and (iii) increasing number of medications. Length of hospital stay was significantly increased in patients with moderate post-operative hyponatraemia compared with normonatraemic patients (30 versus 21 days; P =< 0.001). The incidence of new-onset post-operative hyponatraemia was not significantly increased by ethnicity, gender, fracture type, functional status or operative procedure.
  
  
  CONCLUSIONS
  hyponatraemia after surgery for hip fracture is common and results in longer hospital stay. This study provides evidence that an average post-operative drop in serum sodium concentration should be expected in this patient group. Moreover, patients taking SSRI or PPI medications may be at increased risk of post-operative hyponatraemia.
authors.affiliation: City Hospital, Sandwell and West Birmingham Hospitals NHS Trust - Postgraduate Centre, Birmingham, UK.
authors.forename: James Edward
authors.initials: JE
authors.lastname: Rudge
authors.affiliation: City Hospital, Sandwell and West Birmingham Hospitals NHS Trust - Postgraduate Centre, Birmingham, UK.
authors.forename: Daniel
authors.initials: D
authors.lastname: Kim
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D015415:Biomarkers / Q000097:blood; D015536:Down-Regulation; D004739:England; D005260:Female; D005592:Fracture Fixation / Q000009:adverse effects*; D006620:Hip Fractures / Q000175:diagnosis / Q000601:surgery*; D006801:Humans; D007010:Hyponatremia / Q000097:blood / Q000175:diagnosis / Q000453:epidemiology*; D015994:Incidence; D007902:Length of Stay; D008297:Male; D008875:Middle Aged; D010343:Patient Admission; D019338:Polypharmacy; D054328:Proton Pump Inhibitors / Q000009:adverse effects; D012189:Retrospective Studies; D012307:Risk Factors; D017367:Selective Serotonin Reuptake Inhibitors / Q000009:adverse effects; D012964:Sodium / Q000097:blood*; D013997:Time Factors; D016896:Treatment Outcome
chemical_list: D015415:Biomarkers; D054328:Proton Pump Inhibitors; D017367:Selective Serotonin Reuptake Inhibitors; D012964:Sodium
keywords: fracture; hip; hyponatraemia; older people; orthopaedic; post-operative