Cancer Diagnosis Program | Biorepositories and Biospecimen Research Branch

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Preanalytical study concerning the influence of tube type and centrifugation conditions on the concentration of calprotectin in ascites.

Author(s): Dorotić A, Siter-Kuprešanin M, Čičak H, Saračević A, Vuljanić D, Troskot Perić R, Alfirević I

Publication: Biochem Med (Zagreb), 2026, Vol. 36, Page 020703

PubMed ID: 41971521 PubMed Review Paper? No

Purpose of Paper

Conclusion of Paper

Studies

1. Study Purpose

    This study compared calprotectin, lactate dehydrogenase (LDH) and potassium levels in case-matched ascites transferred and stored in clot activator, K₂EDTA and lithium heparin tubes and then centrifuged at 400 g, 1,500 g or 3,000 g. Ascites was collected from the lower left or right quadrant of the abdomen of twenty supine patients with advanced or suspected liver cirrhosis and patients with malignancies along with symptoms necessitating diagnostic paracentesis (abdominal pain, fever, encephalopathy, hypotension, renal failure, acidosis or peripheral leukocytosis). After collection, ascites was transferred in triplicate into K₂EDTA tubes (lavender top), clot activator tubes (red top) and lithium heparin tubes (green top).  Tubes were mixed and case-matched specimens were centrifuged at 400 g for 15 minutes, at 1,500 g for 15 minutes or at 3,000 g for 15 minutes. Calprotectin levels were measured using the Bühlmann fCAL turbo test. Levels of potassium and LDH were quantified using an auto-analyzer (potassium not measured in K₂EDTA specimens). Data did not have a normal distribution, so statistical significance was evaluated using the Friedman test. A > 14% change in calprotectin levels relative to levels in the clot activator tube centrifuged at 15,000 g for 15 min (control) was considered clinically significant.

   Summary of Findings:

   Calprotectin levels were highest in ascites from clot activator tubes centrifuged at 1,500 g for 15 min (control, median 0.349 mg/L). Compared to the control, calprotectin levels were significantly lower in ascites collected in K₂EDTA tubes and centrifuged at 400 g (median 0.121 mg/L, P<0.001), 1,500 g (median 0.162 mg/L, P<0.001) or 3,000 g (median 0.109 mg/L, P<0.001) for 15 min and in lithium heparin ascites centrifuged at 400 g for 15 min (median 0.186 mg/L, P<0.0001).  Importantly, the bias in calprotectin levels relative to the control exceeded the 14% threshold for clinical significance for all specimens collected in K₂EDTA or lithium heparin tubes, regardless of centrifugation speed and for clot activator tubes centrifuged at 400 or 3,000 g for 15 min instead of 1,500 g. Potassium levels did not differ between ascites collected in clot activator and lithium heparin tubes (K₂EDTA not compared), regardless of centrifugation speed.  LDH levels were lower in K₂EDTA ascites centrifuged at 1,500 or 3,000 g (median 66 and 67 U/L) than in clot activator ascites centrifuged at 400 g, 1,500 g, or 3,000 g (median 68, 69 and 68 U/L, respectively; P=0.046).  The authors concluded that calprotectin should be measured in ascites collected in clot activator tubes and centrifuged at 15,000 g for 15 min.

   Biospecimens

   • Bodily Fluid - Ascites

   Preservative Types

   • None (Fresh)

   Diagnoses:

   • Cirrhosis
   • Other diagnoses
   • Neoplastic - Other

   Platform:

   Analyte	Technology Platform
   Electrolyte/Metal	Clinical chemistry/auto analyzer
   Protein	Clinical chemistry/auto analyzer

   Pre-analytical Factors:

   Classification	Pre-analytical Factor	Value(s)
   Biospecimen Acquisition	Type of collection container/solution	Clot activator tube Lithium heparin tube K2EDTA tube
   Biospecimen Acquisition	Anticoagulant	Lithium heparin Potassium EDTA None
   Biospecimen Aliquots and Components	Centrifugation	Multiple speeds compared

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