Roch have reformulated their Testosterone assay, to get rid of interferences
to improve the measurement of female levels. However, it appears that in
doing so they may also have changed the male levels too, if the quoted guide
reference rangesa are anything to go by.
Has anyone looked at this assay to see if the levels achieved with the new
assay can be used against the older levels. This is important as the new upper
limit for female samples is about 50% of the upper limit being quoted by the
laboratory we currently send high samples to for measurement after extraction.
Also it looks like we will not be seeing the large number of males with low
Testosterone levels but normal FSH and LH levels either based on the quoted
ranges. (Our endocrinologists are terming these patients as having
eugonadotrophic hypogonadism).
I know the old assay left a lot to be desired, but how does this new assay
agree with other assays out there regarding reference values?
It will be interesting to see where this new assay sits on the Sterdoid EQA
scheme, as the current assay gives lower values than other direct assays.
Also, will the organisers be assigning a seperate group for the new formulation,
otherwise, if both kits are used to report results, then the apparent
performance will deteriorate for the Roche group.
Yes I know I am putting my head up there, but as this kit is going to replace
the existing one by 31st May 2010, I think it will be useful to get as much
information as possible before the old kit supplies run out.
Regards,
Gary Mascall
Consultant Clinical Scientist
Worcestershire Acute Hospitals NHS Trust
Old Assay
Male - 9.8 to 27.8 nmol/L
Female - 0.22 to 2.9 nmol/L
New Assay
Male (20 to 50 years) - 7.58 to 31.4 nmol/L
Male ( > 50 years) - 4.57 to 31.2 nmol/L
Female (21 to 50 years) - 0.2 to 1.78 nmol/L
Female ( >50 years) - <0.087 to 1.79 nmol/L
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