title: Impact of experimental hypercalcemia on routine haemostasis testing.
abstract: BACKGROUND
  The blood to anticoagulant ratio is standardized according to the physiological calcium concentration in blood samples conventionally used for hemostasis testing. Specifically, one fixed volume of 0.109 mmol/L sodium citrate is added to 9 volumes of blood. Since little is known about the impact of hypercalcemia on the calcium-binding capacity of citrate, this study was planned to investigate the effect of experimental hypercalcemia on routine hemostasis testing.
  
  
  METHODS
  Fifteen pooled citrated plasmas with matching lithium-heparin pooled plasma from patients with different values of prothrombin time (PT) were divided in three aliquots of 0.6mL each. The first paired aliquots of both citrate and lithium-heparin plasma were supplemented with 60μL of saline, the second paired aliquots with 30μL of saline and 30μL of calcium chloride and the third paired aliquots with 60μL of calcium chloride. Total and ionized calcium was measured in all aliquots of citrate and lithium-heparin plasma, whereas PT, activated partial thromboplastin time (APTT) and fibrinogen were measured in citrate plasma aliquots.
  
  
  RESULTS
  Total calcium concentration gradually increased in both lithium-heparin and citrate plasma aliquots 2 and 3 compared to baseline aliquot 1. The concentration of ionized calcium also gradually increased in lithium-heparin plasma aliquots 2 and 3, whereas it remained immeasurable (i.e., <0.10 mmol/L) in all citrate plasma aliquots. No significant differences were observed for values of PT, APTT and fibrinogen in citrate plasma aliquots 2 and 3 compared to the baseline aliquot 1, with a mean bias was always comprised within the desirable quality specifications derived from biological variability data.
  
  
  CONCLUSIONS
  Hypercalcemia, up to severe hypercalcemia does not generate significant bias in results of first-line coagulations tests, so that hypothetical consideration of adjusting citrate-blood ratio is unjustified in hypercalcemic patients.
authors.affiliation: Section of Clinical Biochemistry, University of Verona, Verona, Italy.
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Lippi
authors.affiliation: Section of Clinical Biochemistry, University of Verona, Verona, Italy.
authors.forename: Gian Luca
authors.initials: GL
authors.lastname: Salvagno
authors.affiliation: Section of Clinical Biochemistry, University of Verona, Verona, Italy.
authors.forename: Giorgio
authors.initials: G
authors.lastname: Brocco
authors.affiliation: Section of Clinical Biochemistry, University of Verona, Verona, Italy.
authors.forename: Matteo
authors.initials: M
authors.lastname: Gelati
authors.affiliation: Section of Clinical Biochemistry, University of Verona, Verona, Italy.
authors.forename: Elisa
authors.identifier: http://orcid.org/0000-0002-2454-0410
authors.initials: E
authors.lastname: Danese
authors.affiliation: Department of Haematology, Sydney Centres for Thrombosis and Haemostasis, Institute of Clinical Pathology and Medical Research, NSW Health Pathology, Westmead Hospital, Westmead, New South Wales, Australia.
authors.forename: Emmanuel J
authors.initials: EJ
authors.lastname: Favaloro
mesh_terms: D000925:Anticoagulants / Q000097:blood; D001777:Blood Coagulation / Q000502:physiology; D019343:Citric Acid / Q000097:blood; D005260:Female; D005340:Fibrinogen / Q000378:metabolism; D006487:Hemostasis; D006493:Heparin / Q000097:blood; D006801:Humans; D006934:Hypercalcemia / Q000097:blood*; D008094:Lithium / Q000097:blood; D008297:Male; D010314:Partial Thromboplastin Time; D011517:Prothrombin Time
chemical_list: D000925:Anticoagulants; D019343:Citric Acid; D005340:Fibrinogen; D006493:Heparin; D008094:Lithium