Many thanks to all who showed interest and provided
valuable comments on this case. It proves that real
life cases are immensly educational when presented to
experienced audience and I would welcome similar
presentations on this mailbase. It seems that we all
agree that:
1. Pseudohypercalcaemia due paraproteinaemia is not
widely reported. John et al reported two cases of
pseudohypercalcaemia associated with IgM
paraproteinaemia (Ann Clin Biochem 1997 Nov;34:
694-6). Vivek kindly supplied 6 further references on
this topic. Probably that is all available so far.
2. How common this phenomenon in paraproteinaemic
patients is uknown. It is probably more common than we
think if we start investigating it. It may even be
present in normocalcaemic patients with
paraproteinaemia. A study involving measurement of
total calcium, ionised calcium and total calcium after
PEG precipitation of immunoglobulins may through some
light on the extent of the problem.
3. In hypercalcaemic paraproteinaemic patients,
ionised calcium should be measured to prove true
hypercalcaemia before embarking on treatment.
Alternatively the crude method of precipitating
immunoglobulins with PEG and re-measuring calcium on
supernatant allowing for dilution, may be employed.
Happy Easter to you all.
Mohammad
=====
Dr. M A Al-Jubouri
Consultant Chemical Pathologist
Whiston Hospital
Prescot
Merseyside L35 5DR
UK
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