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We compared

the performance of the D.A.T. method with

that of amylase patients. amylase healthy

the Pantrak

method

activity

in

110 urine

by using specimens

We also generated a reference from the results for timed urine volunteers.

both to measure from hospitalized

interval

for

urine

specimens

from

95

Materials and Methods

Reagents.

Pantrak

and

D.A.T.

reagents

(supplied

by

Beh-

ring Diagnostics, with de-ionized

San Diego, CA water according

92112) were reconstituted

to

specifications

in

the

manufacturer’

s inserts. Reagent vials were gently agitated

for 10 mm after reconstitution,

One

drop

of ‘Wetting

Agent

W”

then stored at 5#{1 un}til

(Technicon,

Tarrytown,

use. NY

10591)

was

added per

7.5 mL

of reagent,

as specified

by the

manufacturer.

Reagents

were

freshly

prepared

daily.

Quality Miami,

control. FL 33152)

Dade’s “Monitrol ES” (American Levels I and II, Beckman’s

Dade, “Triad”

(Beckman Instruments, and Fisher’s “UriChem”

Brea, CA 92621) (Fisher Scientific,

Levels 1 and 3, Orangeburg, NY

10962) Level Monitrol was

I were used reconstituted

as quality-control

materials.

with

diluent

according

to

the

manufacturer’s

specifications;

UriChem

was reconstituted

with

25

mL

of de-ionized water.

Triad

requires

no reconsti-

tution. All beginning

five materials were assayed in and end of each set of patients’

duplicate at the

urine

samples.

Apparatus

and analytical

performed

at 37#{17 inC an

procedures. All RA-1000 analyzer

assays were (Technicon

Instruments tinge for

Corp., Pantrak

Tarrytown, and D.A.T.

NY 10591). Instrument set- assays differed only with

respect to sample volume volume (335 and 359 pL,

(8 and 6 giL, respectively), reagent respectively), and read-delay time

(5 and 1 mm, respectively). All specimens assayed in duplicate.

were sampled and

Specimens.

For comparison of

untimed University

urine of

specimens from Virginia Hospital

the two

methods, we used

urines

submitted to

the

Clinical

Laboratories

for

routine or urgent the 110 specimens

(“stat”) were

urinalysis. Approximately selected without conscious

half of bias; the

rest

were

screened

for

above-normal

amylase

activity

in

order to Screened

expand the distribution

specimens

were

selected

of data for comparison.

on

the

basis

of

either

above-normal relative

history

of pancreatitis.

density (specific gravity) Specimens were stored

or a clinical at 5#{17until

analysis (no longer than fuged the specimens at

two days). Before assay, we centri-

1000

x

g.

Amylase

activity

was

measured concurrently

by the direct

and

comparison

meth-

ods in

a

single

RA-1000

instrument.

Subjects for the reference-interval

study were selected

from

hospital

employees

who

were

without

acute

or

chronic

illness and were in population consisted age of 32 (SD 8) years

apparent good health. The reference of 50 men and 45 women, with a mean (range: 21-59). Subjects were instruct-

ed to void and approximately 2

then collect the h later, recording

entire urine

specimen

the exact time

interval.

MonitrolI

46 (7.3)

MonitrolII

351 (3.5)

Triad 1

71(7.0)

Triad 3

406 (3.8)

Table 1. EstImates of Total Imprecision In Our Day-to- Day Precision Study Amytase actIvity, U/L(and CV,%)

Sample

Pantrak (n = 24)

D.A.T.(n = 28)

42 (5.0)

334 (3.7) 50 (6.0) 260 (42)

0

  • -

    J

0 0

D.A.T U/h

Fig. 1. Histogram of amylaseactivity unitsexcretedper hour by 95 healthyvolunteersages21-59: 50 men, 45 women

All specimen collections were begun and completed between 0600 and 1800. After the volume was noted, the amylase activity was measured by the D.A.T. method and amylase excretion was expressed as U/h in order to compensate for

variable degrees of hydration. Human pancreatic and salivary as described earlier (11).

amylases were purified

Resufts

Table 1 gives day-to-day precision data for the direct (D.A.T.) method and for the comparison method. Precision

was calculated by using the first of duplicate determinations

for

each

of the

four

quality-control

materials.

Within-run

CVs, based on the duplicates, were 3.5% or less in all

(not shown).

Fisher’s UriChem

was

deemed

unsuitable

quality-control

material for

urine

amylase

because

cases as a of its

instability no assay

over one or two data for amylase

days. The manufacturer activity in this product,

provides although

our results suggested that

amylase activity

in the

prepared material rim precision for

was 100

to 130

the urine

control

U/L (by D.A.T.). was acceptable

freshly- Within- by each

method (for Pantrak: 5%, n = 14).

CV

=

3%, n =

12; for D.A.T.: CV

=

Regression analysis of results from determination

lass

in

untimed

urine

specimens

by

the

direct

of amy- (y) and

comparison (x) methods yielded a slope of the regression line

of 0.947 estimate

and ay-intercept

of 4 U/L. The standard

was

25

UIL.

Amylase

activities

ranged

error

from

of the 11 to

1465 UIL,

and the mean activity

was 358 U/L (SD =

U/L)

as

measured

by the

comparison

method.

The

mean

275 and

SD of the y-assay (direct

respectively.

Twenty-five

lase activities

exceeding

method) were 343 and 267 of the urine specimens had 500 U/L, for 15 it was >700

U/L, amy- UIL,

and for three it was >1000 To assess the relative Pantrak reagents toward

U/L. reactivities the salivary

of the D.A.T. and and pancreatic amy-

lass isoenzymes,

human

isoenzymes

we measured

by

the

direct

the and

activities of purified comparison methods.

The

activities of

the salivary

346

and 322 U/L

as measured

isoenzyme preparation were by the direct and comparison

methods,

respectively.

Corresponding

atic

isoenzyme

preparation

were

276

values for the and 274 U/L.

pancre-

Results of the reference-interval

study are summarized

in

Figure 1. The mean units of aniylase

hour

for

the

reference

population

was

activity excreted per 7.2, with a standard

CLINICALCHEMISTRY, Vol. 34, No. 4, 1988 755

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