Gel Bottles: Instructions for Use

Indications:

Gel tubes should be used for all serum sample submissions.

Notes:

Where red blood cells remain in contact with serum, autolysis can allow leakage of intracellular contents into the serum. This may affect biochemistry analysis and induce erroneous results. With time, the cells may lyse completely (haemolysis) and make the sample of little diagnostic value.

While many tests are affected by haemolysis, the effects are greatest where potassium, phosphorus, Alkaline Phosphatase, LDH and Total Protein are to be assayed.

With centrifugation at sufficient speed, gel tubes form an inert, impermeable barrier between the red cells and the serum. This prevents haemolysis and samples can be sent without further preparation. To minimise the effects of red cell lysis, samples should be spun soon after clotting.

Protocol:

• Take blood sample and fill the gel tube slowly after removing the needle.
• Allow sample to stand for 20 minutes. Check to ensure sample has clotted.
• Centrifuge at high speed for 5 minutes. The gel will now have formed an inert barrier between the cells and serum.
• Check serum separation is complete. Re-spin if there is not a clear layer between serum and the red cells.
• If the serum is already haemolysed, this may reflect red blood cell damage caused at sampling or be part of the disease condition present (increased red blood cell fragility and/or haemolysis present). A repeat sample is indicated initially before submitting to the laboratory.
• Submit tube(s) and request form to the laboratory.