Alt; Ammonium Heparin Tube Not Acceptable; Alt/Ast Activated Versus Alt/Ast; Differences - Abbott AEROSET Troubleshooting Manual

Assays/Reagents

ALT

Ammonium Heparin Tube Not Acceptable

ALT/AST Activated Versus ALT/AST

Differences

ALT Activated

Ammonium Heparin Tube Not Acceptable
104
PROPRIETARY INFORMATION
CONFIDENTIAL MATERIAL
Not for Customer Distribution
Ammonium heparin was removed from the list of approved
anticoagulants for ALT, ALT-A, AST, and AST-A. The reference
used to support this recommendation is Burtis CA, Ashwood
ER, editors. Tietz Textbook of Clinical Chemistry, 2nd ed.
Philadelphia, PA: WB Saunders, 1994:795.
This reference states:
"Elevated levels of
some sera from patients with parenchymal liver disease. If
ammonia is also present in the serum specimen or in one of
the reagents, the GLD reaction will proceed and interfere with
the AST determination by consuming oxoglutarate and NADH.
Thus, use of ammonia-free reagents is recommended."
ALT Activated and AST Activated assays contain the coenzyme
(activator) pyridoxal-5-phosphate (P-5-P); ALT and AST assays
do not contain P-5-P. Most laboratories in the U.S. prefer
non-activated formulations, while use of activated assays is
prevalent in European laboratories. The IVD Directive is
encouraging laboratories to use activated forms of the reagent.
There is no difference in reaction, and there are minimal
differences with most patient results. The activated reagent is
useful in patients with nutritional deficiencies, where the
coenzyme P-5-P level may be decreased with resultant
decreased enzyme activity. With these patients, the activated
reagent provides an advantage because it activates enzymes
that may not otherwise be fully active if the patient has a P-5-P
deficiency.
However, ALT Activated and AST Activated assays require
reconstitution, and have shorter onboard stability than the
non-activated assays—seven days vs. 27 days.
Refer to ALT in this section for details.
-GLD (EC 1.4.1.3) may be encountered in
L
AEROSET
94816-107—November 2004
®
System Troubleshooting Guide