At 2001-03-15 09:49 +0000, Dave Hullin wrote:
> Gordon
>
>Given that the paraprotein was an IgM could the hypercalcaemia be
>artefactual ?
Most formulae correct calcium only for the binding to albumin. However all
proteins have a certain calcium-binding capacity, and this includes also
paraproteins.
Obviously it is impossible to compensate for calcium bound to all kinds of
proteins and hence, if paraprotein is present, a falsely high value is
expected.
This further underlines the importance of direct measurement of ionized
calcium in ANY case where an error of calcium metabolism is suspected.
As Gordon mentioned, serum electrophoresis revealed the correct diagnosis
and probably the patient had no error in calcium metabolism. This
assumption, however, can ONLY be confirmed by direct measurement of ionized
calcium.
Hypothetically also Li may interfere with the the analytical method used
for the calcium measurement. I suppose that this source of error was taken
into account when the method was set up in the laboratory.
IgM paraproteinemia often is associated with increased plasma viscosity and
cold agglutination protein. Did the symtoms support this? Did the patient
suffer from bad circulation escpecially in hands and feet and i cold weather?
How was the patient treated? Plasmaferesis?
Mr Sten Öhman, PhD
Sten Öhman, PhD
Elfin Lab & Milieuconsult
P O Box 133
S-590 70 Ljungsbro
Sweden
Tel Nat: 013-368940 Int: +46 13 368940
Fax Nat: 013-368941 Int: +46 13 368941
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