Hemolyzed Tubes - scientific question

[phoebe2020, BSN, RN]

I have a sciencey question for y'all. ?

This morning I submitted a CBC (one purple top) and BMP/Mag (one green top) for my patient - I drew them all from the same spot at the same time. Now, I did draw them from an PIV. I am aware of the increased risk for hemolysis when drawing from a peripheral, but our hospital policy allows this in the ICU... and to save a stick, it's always a risk I'm willing to take for the patient's sake. 

That being said, lab were able to result the CBC with no problem. Then, they resulted my Mag--no problem. But then they call to say that my BMP specimen hemolyzed--it's the same vial from which they just managed to result a magnesium.  

Can someone explain to me why this happens? How are they able to get some results from the same vial that apparently hemolyzes minutes later? I have never understood this phenomenon.  

[canoehead, BSN, RN]

This is a great question.

[JBMmom, MSN, NP]

I know sometimes our BMP results don't all cross over at the same time. Perhaps they didn't know the extent of the hemolysis until the potassium results was outside of the range?

[Wuzzie]

The Mag may have been resulted but those results were unreliable and they shouldn't have finalized it. 

[mdsRN2005, ASN, BSN, RN]

CBC results are not affected by hemolysis so they can usually run it regardless.  In a BMP the potassium will be falsely elevated so they usually won't run the panel.  However there are other tests such as liver and pancreatic enzymes that are run from the same tube that can be processed since they're not affected by hemolysis either. 

[Leader25, ASN, BSN, RN]

phoebe2020 said:

That being said, lab were able to result the CBC with no problem. Then, they resulted my Mag--no problem. But then they call to say that my BMP specimen hemolyzed--it's the same vial from which they just managed to result a magnesium.  

In our place this lab results etc is the mystery of the universe,either it clots,not enough,lost,loose label,...enough nonsense to make you lose your mind.Tests repeated 3-4x on very compromised tiny patients, and then some docs would eventually try a vein ,if any good ones left,administration refused to change policy or look into our complaints.All they did was change  lancets and warmers to some Spring stick which never worked well.Daily frustration,when you running behind in your work and have to keep  answering "clotted,lost,insufficent"type phone calls from that lousy lab.

Hope with all my heart you solve the dilemma.

[NRSKarenRN, BSN, RN]

Ugh, remember those lab calls, always on patient with fragile/limited vein sites. doing home lab draws, found very warm compress helped, along with not overinverting blood tubes, promptly centrifuged tubes -kept centrifuge on passenger floorboard during my 10yrs w/ home infusion.

A Quick-Reference Tool for Hemolysis Status

Prevention of hemolysis is important to preserve the quality of a serum sample for testing.

Best Practices to Prevent Hemolysis

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Use the correct needle size for blood collection (20-22 gauge).

Avoid using butterfly needles, unless specifically requested by patient.

Warm up the venipuncture site to increase blood flow.

Allow disinfectant on venipuncture site to dry completely.

Collect blood sample in the correct blood collection tube (red cap/tiger tube = without anticoagulants).

Collect the correct volume for the tube size. Use smaller tubes for difficult draws.

Coagulation: place the tube in an upright position for 15-30 minutes at room temperature. Then store at 4°C.

Centrifuge samples for serum separation within 4 hours of sample collection.

If tests are performed within 48 hours of collection, transfer serum to a sample tube (cryovial) and store at 4°C.

If tests will be performed more than 48 hours after collection, aliquot samples and store at -20°C or lower.

Hemolysis: What is it and How to Prevent it.

Suffice it to say hemolysis is just all-around nasty. So how do those who collect specimens prevent the lab from reporting inaccurate results? Check your practices to minimize these seven top causes:

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Avoid line draws---IV devices are notorious for hemolyzing red cells. Unless you're using a device like PIVO, perform a venipuncture instead;

Avoid vigorous mixing---think of red cells as fragile crystal orbs that fracture with the least amount of disturbance;

Avoid excessive pulling pressure when using syringes---red cells don't tolerate the excessive turbulence from forcefully withdrawing the plunger of the syringe;

Don't rim clots---rimming clots to remove fibrin invariably ruptures red cells at the same time;

Position the needle properly---a needle partially occluded by the vein wall is a needle that hemolyzes red cells;

Prewarm skin puncture sites---this reduces the need to excessively squeeze the tissue, which hemolyzes red cells;

Fill tubes fully---an excessive concentration of anticoagulant when tubes are underfilled is hard on fragile red cell membranes.

Collecting Blood from Patients with Vascular Lines

Identifying and managing hemolysis interference with CBC specimens