I wonder if anyone can make any clever suggestions about the mechanism of
interference with this sample:
35 year old Chinese woman who presented with clinical thyrotoxicosis
FT4 on ECi (Lab 1)was >50 pmol/L (done at another lab so I don't have exact
details)
TSH on ECi (Lab 1) 3-4 (repeatedly about this level)
Clinicians became excited about the possibility of a TSHoma but finally sent the
sample to us to check.
FT4 on Architect was 56
TSH on Architect was <0.005
TSH on Elecsys was <0.005
TSH on Axsym was 0.672
Rheumatoid factor negative
TSH on ECi at another lab (Lab 2) 3.25
TSH dilution at Lab 2 ECi (250 patient + 500 thyrotoxic serum) calculates up to
3.07
Mouse serum on ECi at Lab 2 (5 mouse + 500 patient) calculates up to 3.12
Mouse serum on ECi at Lab 2 (50 mouse + 150 patient) calculates to 1.57
FSH 2.5
LH 3.0
hCG 2.0
In the meantime, the patient was treated for Graves disease and finally another
sample was sent to us 2 months after the initial one:
FT4 on ECi (Lab 1)10.7
TSH on ECi (Lab 1) 1.21
FT4 on Architect 10.24
TSH on Architect 0.0079
OCD kindly gave me a heterophilic antibody blocking tube from Scantibodies:
Straight TSH on ECi (Lab 2) 0.856
Treated TSH on ECi (Lab 2) 0.246
TSH on mouse serum on ECi (Lab 2) [in case anyone is interested] 0.064
Hmm....I'm running out of specimen. Any suggestions as to the mechanism here
and any further tests?
Thank you for any suggestions.
Rob Hawkins
Department of Pathology and Laboratory Medicine
Tan Tock Seng Hospital
Sinagpore
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