We are also seeing 30-40% lower values with new PTH assay.  We have not completed the reference range study, but it is ironic to see that DPC is providing about the same reference ranges for both kits.  The question is if the new ranges are right, were previous ranges provided wrong!!!

Uttam Garg, PhD, DABCC
Associate Professor
Director of Clinical Chem & Tox Labs
Children's Mercy Hospital
Kansas City, MO 64108
Phone: 816-234-3803
Fax: 816-234-3794

-----Original Message-----
From:   Collins, Wayne [SMTP:[log in to unmask]]
Sent:   Tuesday, November 06, 2001 8:09 AM
To:     [log in to unmask]
Subject:        DPC Immulite new PTH assay Cat No. LKPP1 or LKPP5

Reviewing the evaluation data for this new PTH kit I have certain concerns
over the 30% decrease in values over the current (but soon to be
unavailable) kit. As well as a reformulation of the antibodies, there is now
also a marked downward shift in results, presumably due to recalibration of
the assay.The DPC data sheet shows good agreement of the new kit with the
Nichols Chemiluminescent and IRMA methods. Is this perhaps the sole
justification for the apparent recalibration of the method ??

My other concern is the reference range stated in the DPC insert: this is
virtually identical for the new and old PTH kits, in spite of a 30 %
difference in results. Square pegs and round holes come to mind.

In the September 2001 NEQAS return for PTH there are 18 laboratories
returning results for the new DPC kit (Immulite plus Immulite 2000). I would
be interested to know what reference range these people use and their
opinions (or anyone else) on manufacturers making such major shifts in
calibration. Is this another case of manufacturers chasing each to obtain
similar EQAS results ?

Wayne Collins
Royal Preston Hospital