Dear Mailbase Members,
I received an interesting sample in the laboratory with some unusual
properties that maybe some one could shed some light on.
There were two blood samples collected from the one patient, a serum sample
in a gel separated tube and an EDTA plasma sample.
The patient was found to have the following results:
Total protein = 128g/L
Albumin = 18g/L
IgG = 89g/L
Kappa = 98g/L
IgG kappa paraprotein by immunofixation.
When the serum sample is separated it forms a gelatinous mass with the
appearance of denatured serum within 30 minutes
(cryoglobulin/cryopreciptitate). Separating the serum and immediately
putting it into a 37 C water bath maintains the sample in a liquid state
with normal appearance. When the primary sample tube was retrieved from the
4 C cold room after being there for 3 days, the serum above the gel
separator had formed a gelatinous mass, however, the serum below the gel
separator which was in contact with the red cell clot had normal appearance.
This could be seen quite easily through the plastic primary tube as the clot
had retracted further on standing. The EDTA plasma sample was recovered
after 3 days storage at 4 C and the plasma appeared quite normal as the red
cells had settled to the bottom. Separating the plasma from the red cells
caused it also to form a gelatinous mass. Trying to warm the serum or
plasma sample at 37 C overnight does not cause the sample to re-"liquify",
i.e. once the conformation of the protein has changed, cannot revert it back
to a liquid state.
In summary, the serum and EDTA plasma when in contact with the red cells
have a normal appearance, even when refrigerated. When the serum or plasma
is separated from the red cells, it denatures irreversibly. Separating the
sample and putting it immediately into a 37 C bath, maintains the sample in
a liquid state for a limited time.
Why is it that the serum or plasma does not denature when in contact with
the red cells even at 4 C for a number of days, but when removed it
denatures??
Thanking you in advance for any replies posted.
Geoff Whittaker
Hospital Scientist
Clinical Chemistry
South Western Area Pathology Service
Liverpool Hospital Sydney.
Email: [log in to unmask]
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