Serum separator gel tubes are widely used in laboratories for blood collection since their advantages. These contain a gel that forms a barrier between serum and clot after centrifugation. Rarely, some conditions may arise from unusual separation patterns. In this case, the floating separator gel due to hyperproteinemia was reported. A 49-year old woman admitted to the chest diseases department. The blood sample was collected into a gel separation tube, transported to the Medical Biochemistry Laboratory within 45 minutes and centrifuged at 1500 g for 10 minutes. The separator gel formed the topmost layer, with the serum in the middle and the clot at the bottom. The sample was recentrifuged, but this atypical phenomenon did not change. The serum was aspirated under the gel layer by a pipette. Biochemical analyses showed markedly elevated total protein concentration (147 g/L). The patient's file revealed that she had no history of chronic disease other than chronic obstructive pulmonary disease. When consulted, the clinician informed us that the patient was directed for further examination because of the high total protein levels. Laboratories should be careful of the limitation of gel separation tubes. In addition, all samples must be visually checked before analysis, as an aspiration of misplaced gel may obstruct the analyzer probes; causing technical problems, time loss, adverse patient outcome, and extra cost.
1. Bowen RA, Remaley AT. Interferences from blood collection tube components on clinical chemistry assays. Biochem Med (Zagreb) 2014;24(1):31–44.
2. Fatás M, Franquelo P, Franquelo R. Anomalous flotation of separator gel: density or viscosity? Clin Chem 2008;54(4):771–2.
3. Demir M, Ozdem S, Sarier M. Abnormal Flotation of Separator Gel in Blood Test Tubes in the Hemodialysis Patients. EJMI 2019;3(4):280–4.
4. Srivastava R, Murphy MJ, Card J, Severn A, Fraser CG. The case of the floating gel. J Clin Pathol 2004;57(12):1333–4.
5. Daves M, Lippi G, Cosio G, Raffagnini A, Peer E, Dangella A, et al. An unusual case of a primary blood collection tube with floating separator gel. J Clin Lab Anal 2012;26(4):246–7.
6. Bowen RA, Hortin GL, Csako G, Otañez OH, Remaley AT. Impact of blood collection devices on clinical chemistry assays. Clin Biochem 2010;43(1-2):4–25.
7. van den Ouweland JM, Church S. High total protein impairs appropriate gel barrier formation in BD Vacutainer blood collection tubes. Clin Chem 2007;53(3):364–5.
8. Chakraborty S, Chowdhury SR, Krishnan P, Sanyal S, Bhattacharya C, Sen S. Improper serum separation on gel tubes: a trivial laboratory problem or an indicator of monoclonal gammopathy? Clin Chem Lab Med 2014;52(12):e275–8.
9. Piyophirapong S, Wongtiraporn W, Sribhen K. Factitious Results in Clinical Chemistry Tests Caused by Common Endogenous Interferents. Siriraj Med J 2010;62:185–8.
10. Pallavi B, Krishnamurthy U. An unique encounter with paraprotenemia. J Lab Physicians 2019;11:391–3.