Contrast Jill V. Hunter,

MB,

BS, MRCP,

FRCR

Patricia

R. N. Kind,

#{149}

Media

PhD

Nonlonic lodinated Contrast Media: Potential Renal Damage Assessed with Enzymuria’ The potential of digital subtraction angiography (DSA) to enable study of the physiology of renal transplantation after a single intravenous injection of nonionic iodinated contrast material stimulated this investigation into the possible nephrotoxicity of the contrast material used. Levels of urinary enzyme activity, used as markers of renal damage, were measured before, immediately after, and up to 72 hours after intravenous injection of nonionic iodinated contrast material in two groups of patients undergoing DSA. Twenty-six patients had undergone renal transplantation and 10 control patients had normal renal function. Both groups showed a transient rise in the level of urinary enzyme activity that peaked within 24 hours and returned to levels obtained before DSA within 72 hours. In the transplantation group, the baseline levels of enzymes were higher, and the response after administration of contrast material was greater. Nevertheless, the duration of the response was the same as in the control group, and the enzyme levels of all patients returned to their pre-DSA baseline levels.

D

(DSA)

Contrast toxicity

giography,

81.12433

giography,

81.1243 1992;

Radiology

I

From

the

media, effects #{149} Con#{149} Digital subtraction an#{149} Enzymes #{149} Renal an-

183:101-104

Pathology

Address

reprint

Massachusetts

requests Division

General

Boston, MA 02114. C RSNA, 1992

contrast

material

dure

itself can

be

is able

to

simultaneously

about both structure and has been of use of the renal transplant and

ad-

and function in the assessment (1). The proce-

is relatively

noninvasive

performed (2).

on

tient basis The potential dinated contrast

an outpa-

nephrotoxicity media has

long

of iobeen

a cause for concern, especially in a transplanted kidney. The purpose of the study reported herein was to assess the degree and reversibility of any membrane damage to a trans-

planted an

kidney

that

intravenous

iodinated

contrast

compare

might

injection

this

of a similar

occur

material

finding

with

injection

after

of nonionic

and the

to effects

of contrast

rial in a group of patients kidneys. Nephrotoxicity

mate-

with normal was assessed

on the basis of changes in levels of urinary enzyme concentration, particularly (NAG), (AAP),

N-acetyl-3-D-glucosaminidase alanine aminopeptidase and y glutamyl transpeptidase

(GGT).

Measurement

zymes

has

index

been

of renal

of these shown

en-

of Radiology

(P.R.N.K.),

(J.V.H.)

St Thomas

to J.V.H., Department of Neurology,

Hospital,

Gray

II,

55 Fruit St,

with men,

cyclosporine aged 29-57

This

group

was

(six women years; mean, studied

and six 40 years).

17 days

to 9

months (mean, 3 months) after they had undergone transplantation. Five of the patients receiving azathioprine and 10 of the patients receiving cyclosporine had a serum creatinine concentration above the accepted upper limit of the reference range (ie, serum creatinine concentration > 120 p.mol/L). Ten consecutive patients referred to the radiology department for intravenous DSA were also invited to participate in the study. The patients in the control group were all normotensive, with normal renal function, as evidenced by a normal serum creatinine level and, when information was available, a normal glomerular filtration rate. They had no history of renal dysfunction. The control patients underwent DSA for reasons unrelated to renal disease. The nine men and one woman were aged 43-75 years (mean, 55 years). All patients were required to give written informed consent prior to entering the study, which had been approved by the local Ethics and Human Studies Committee. The characteristics of the patients who had undergone renal transplantation reflected those of a cross section of the transplantation population being monitored and managed at our institution.

to be a sensi-

tubular

damage

Clinical

Methods

(3-5). All patients were asked to fast for 4 hours prior to DSA, but no fluid restriction

AND

METHODS

Patients

Hospital, London. From the 1990 RSNA scientific assembly. Received November 29, 1990; revision requested January 3, 1991; revision received November 19; accepted December 2. of Radiology,

angiography

intravenously

information

PATIENTS

Departments

and Chemical

with

ministered

yield

tive Index terms: trast media,

subtraction

IGITAL

A total of 36 patients were studied. Twenty-six consecutive renal transplantation patients who were attending the outpatient clinic for a routine follow-up examination were invited to participate in the study. Fourteen of the transplantation patients were being treated with azathioprime (Wellcome Diagnostics, Research Triangle Park, NC) and prednisolone (Miles, Elkhart, Ind) (six women and eight men, aged 26-55 years; mean, 40 years). This group of patients was studied 6 weeks to 10.75 years (mean, 5.5 years) after they had undergone transplantation. Twelve of the patients were being treated

was

imposed;

mL H20

indeed,

was

examination. by

given

a water

orally

DSA studies

inserting

a 5-F

catheter

load

I hour

were into

of 200

before

the

performed the

right

atrium or superior vena cava via an antecubital or femoral vein, with a modified Seldinger technique, as a sterile procedure. Forty milliliters of nonionic iodinated contrast material (iohexol, Omnipaque [350 mg of iodine per milliterj; Nycomed, Oslo) was injected at a rate of 25 mL/sec for each acquisition. Patients

Abbreviations: dase, DSA

=

AAP = alanine aminopeptidigital subtraction angiography,

= v glutamyl transpeptidase, N-acetyl-3-D-glucosaminidase.

GGT

NAG

=

101

Resulis

of Mean

Urinary

Enzyme

Activity

from

Spot Urine

Samples

in 36 Patients Pati ents Who Underw

ent

Transplantation

Azathioprine Normal Serum Creatinine (n = 9)

Control Subjects (n

NAG

(U/mmol

urinary

Mean

7.00 7.80 10.40 7.80 8.00

132 1.00 1.68 1.02 1.46

10.65

1.33

12.30

1.21

11.20

9.21

2.02

18.48

7.78 10.52

1.09 0.99

15.05 10.46

2.13 1.07

12.30 10.20

1.45 1.91 1.11

0.63

10.50

1.34

5.52

1.42

7.86

1.09

6.30

1.74

3.56

2.59

331

0.46

1.12 0.58

3.24 5.47 4.09 3.60

0.56 0.34 0.80

3.10

4.60 4.08 8.16 5.28 4.00

1.40

3.98 3.43 3.38

0.86 0.49 0.89 0.73 0.46

0.77

5.96 3.32

0.49 0.40 1.18 0.44

1.62 1.93 3.69 1.72

0.17 0.26 0.55 0.21

1.31 1.50 2.69 2.29

0.25 0.21 0.42 0.72

1.81 2.04 4.98 4.02

0.34 0.27 0.34 1.10

1.53

0.18 3.87

1.02 100.2

0.21 6.63

1.88 180.4

0.15 21.9

1.33 128.9

0.42 17.2

3.77

=

standard

77.1

renal transplantation such injection of con-

trast

control

material.

The

2.77

patients

re-

ceived one to five injections (mean, three injections) of 40 mL of iohexol, depending on why they were undergoing DSA. Urine and blood samples were obtained immediately before and after DSA. Urine samples were also collected on the morning of the DSA

and

daily

for

2 more

days

at

intervals.

Nephrotoxicity

was

assessed

by

mea-

surement of the urinary activity of NAG, AAP, and GGT. NAG is a proximal renal tubular lysosomal enzyme, while AAP and GGT are present in the brush border cells of the proximal tubule. All of these enzymes have been shown to be sensitive markers of nephrotoxicity and have been used extensively in the clinical environment

to document

Laboratory Urine

damage

were as the

were

urine

stored

samples

analyzed final

Radiology

#{149}

Mean

SEM

Mean

All

Creatinine (n = 10)

Patients (n = 12)

SEM

Mean

SEM

Mean

SEM

8.30 5.25 8.70 17.15 9.90

2.12 2.62 3.39 13.2 2.40

31.46 27.51 40.98 36.41 30.78

3.73 3.71

27.60 23.80

5.95 5.56

4.66

35.60

8.11

8.45 4.75

33.20 27.30

7.54 7.80

2.18

0.52 0.65

3.72 3.16 2.82

0.71 0.71 0.79 0.06 0.03

specimen

1.09

1.49 1.69

0.19 0.17

1.35

1.15

331

0.47

2.91

0.54

2.75 2.55 1.35 110.5

2.76 2.40 0.07 636

used.

In all three assays, use of a small volume of sample relative to the volume of bufferreduced

to a minimum

any

in-

terference by inhibitors. It was therefore not necessary for the samples to undergo dialysis before measurement of enzyme activity. The concentration of nonionic at 4#{176}C prior from

a single

simultaneously had

been

as re-

ceived. Urinary NAG activity was measured by using an automated fluorometric procedure (14), with minor modifications (15). GGT activity was measured by using centrifugal analysis (Centrifichem 400; Union Carbide, Danbury, Conn) with kit reagents (catalog no. 543098; Boehringer Mannheim, Indianapolis, md).

102

SEM

A method for analysis of AAP activity (16) was adapted for the centrifugal analyzer. Twenty microliters of urine was diluted with 65 L of buffer (tromethamine [TRIS] hydrochloride, 59 mmol/L; pH, 7.8) and 250 L of alanine-4-nitro-analide hydrochloride (2.6 mmol/L in buffer) to give a final optimum substrate concentration of approximately 2 mmol/L. The reaction was carried out at 37#{176}C, and the optical density of the released p-nitroalanine was read at 405 nm. The enzyme activity in units per liter was calculated by using a factor of 1,776 to take into account the molar extraction of p-nitroanaline and the volume of urine and of buffer-substrate

substrate

(3-13).

Methods

The

patient soon

renal

samples

to assay.

Mean

High

Serum

2.34

4.36

0.51

4.93 9.10 5.93 4.69

0.67 1.17

0.64

5.98

0.64

4.95 10.43

9.26 6.04 188.1

4.00 4.50

0.60

8.20 5.47

0.57

4.38

0.99 0.95

5.21

0.71

0.96 1.80 1.03 1.12

1.60 1.47

4.32

1.75

9.15

2.23

1.80

8.14

1.02

5.26 175.20

2.42 2.02

38.3

25.1

of the mean.

error

who had undergone received only one

after

Patients (n = 14)

SEM

DSA

Note.-SEM

24-hour

Creatinine (n = 5)

Normal Serum Creatinine (n = 2)

creatinine)

Day 2 Day 3 Day 4 AAP (U/mmol of urinary creatinine) Before DSA After DSA Day 2 Day 3 Day 4 Serum creatinine (.tmol/L)

day

SEM

All

Mean

DSA

After

10)

High

Serum

of

urinary creatinine) Before DSA After DSA Day 2 Day 3 Day 4 GGT (U/mmol of Before

=

Cyclosporine

contrast

material

in the

urine,

after

a sin-

gle intravenous injection, was calculated. A quantity of contrast material was then added to one-half of a pre-DSA sample of urine to simulate a “physiologic” content of filtered contrast material. Both halves of the sample were then analyzed; no differences were found in the enzyme activities. It was therefore shown that contrast material present in the concentrations to be found in urine did not alter the assay results. Urine enzyme levels were expressed as

a ratio thereby

of urine creatinine concentration, compensating to some degree for variations in the rates of flow of urine (7,17). In this study all three enzymes were expressed in terms of level of urine creatinine, which was measured with a centrifugal

analyzer

by

using

the

standard

alka-

line picrate method. The baseline values were compared with established normal reference values for NAG ( < 10 U/mmol urinary creatinine), GGT ( < 5.9 U/mmol urinary creatinine), and AAP ( < 1.5 U/mmol urinary creatinine) (17).

RESULTS The Table.

results are summarized The data were analyzed

ing standard statistical are displayed in Figures baseline enzyme levels just above the reference

in the by us-

methods and 1-3. The were within ranges for

or

the 10 control patients (an older age group), for the nine transplantation patients who were treated with azathioprine and who had serum creatinine levels in the normal range (mean, 100.2 imol/L), and for the two transplantation patients who were treated with cyclosporine and who had serum creatinine levels in the normal range (mean, 110.5 p.mol/L). The baseline levels of NAG and AAP for patients who were treated with cyclosporine and who had elevated serum creatinine levels (mean, 188.1

April

1992

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(normal).

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120

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(b, c) Curves

p.mol/L)

and

of the mean

show

(c) com-

are plotted.

of the

Several icity

mechanisms

secondary

of nephrotox-

to administration

Figure

3.

urinary

Graphs

depict

GGT before

levels

DSA and

of activity

of

immediately

after DSA and at 24, 48, and 72 hours after DSA. (a) Curves show the responses of patients in the three groups who had serum creatinine levels below 120 imol/L (normal). (b, c) Curves show (b) responses of patients with elevated serum creatinine levels ( > 120 p.mol/L) and (c) composite values for all patients by group. Mean values ± standard error of the mean are plotted.

increased more than levels of either GGT or NAG. Since AAP is localized superficially in the brush border membrane, it may be released more

DISCUSSION

The

control group, albeit at a higher level. Thus in all patients, irrespective of their serum creatinine status, urinary enzyme activity returned to the preDSA baseline levels. Volume

below creatinine values

three

baseline levels of NAG and AAP for the patients who were treated with azathioprine and who had elevated serum creatinine levels (mean, 170.1 p.mol/L) were just above the reference ranges. The urinary enzyme activity in all groups rose within 24 hours of DSA and returned to pre-DSA levels within 72 hours; the predominant effect was on the level of AAP. Patients who had undergone renal transplantation and who had normal creatinine levels had levels of enzymuria similar to those of the control group. Most of the abnormal elevation in enzyme levels was seen in patients with high initial serum creatinine levels. It should be noted, however, that even in these compromised patients, the pattern of enzyme

L4()

Tim.

C.

1, 2. (1) Graphs depict levels of activity of urinary NAG before DSA and immediately after DSA and at 24, 48, and 72 hours after DSA. (a) Curves show the responses of patients in the three groups who had serum creatinine levels below 120 imol/L (normal). (b, c) Curves show (b) responses of patients with elevated serum creatinine levels ( > 120 p.mol/L) and (c) composite values for all patients by group. Mean values ± standard error of the mean are plotted. (2) Graphs depict levels of activity of urinary AAP before DSA and immediately after DSA and at 24, 48, and 72 hours after DSA. (a) Curves show the responses of patients in the

groups

F5

DSAPsst’DSA24s.,.4l,s72sss

Time

2c.

(b) responses

,,

Sample

Figures

three

S

2

of

easily

than

which

enzymes

nal damage instead of 32-microgIobulin, a low-molecular-weight protein, because of the greater stability of the enzymes. Measurement of urinary

gested that the enzyme release was part of a diuretic phase response (12). In four patients studied more recently, levels of AAP were found to be higher at 12 hours than at 24 hours

NAG

after

activity

used

as markers

of re-

is a well-established

NAG,

membrane

is integrated

into

were

the

GGT,

iodinated contrast material have been proposed (18). These include glomerular injury, as evidenced by nonspecific proteinuria, and tubular injury, reflected by increased activity of tubule-specific enzymes in the urine. In our study, levels of specific urinary

which

Burchardt tients

phritis, crease

itself

(3,11),

is a lysosomal

et al, when with

acute

found in AAP

administration

DSA,

studying

or chronic

papyelone-

a four- to fivefold excretion after of diatrizoate

which

or

enzyme.

would

inand

sug-

be in keeping

means of detecting and monitoring renal damage (3-10). The activity in the urine of both GGT and AAP, two proximal tubular brush border en-

with this hypothesis. The minor changes seen in the level of AAP in the control group and in the azathioprime-treated transplantation group

zymes,

may,

has

also

been

shown

to be in-

creased with renal damage, and measurement of their levels can be used for monitoring nephrotoxicity (11-13). Endogenous renal GGT is a sensitive indicator of renal ischemic injury and renal homograft rejection in humans (13). In our series, levels of AAP

therefore,

be the

result

of in-

creased fluid intake (as part of the preparation for the procedure) rather than of direct tubular cell damage, especially since there was no significant rise in NAG or GGT activity (which would be considered an mdication of nephrotoxicity). Radiology

103

#{149}

The enzyme levels of all patients with a normal serum creatinine value behaved in a comparable fashion. In

In this study of the effects of nonionic iodinated contrast material on the kidney as evaluated on the

those

basis

of urinary

tion,

the

patients

with

elevated

serum

creatinine levels, findings were interesting in the patients treated with cyclosporine compared with findings in the patients treated with azathioprime: Not only did the patients treated with cyclosporine have higher baseline levels of enzyme activity, but they

also

had

the

greatest

response

to

the administration of nonionic contrast medium. This difference in enzyme activity might be explained by the fact that transplantation had been performed more recently in the group receiving cyclosporine (mean, 3 months) than in the group receiving azathioprine (mean, 5.5 years); hence, there was a difference in the duration of immunosuppressive therapy. However, there is evidence that patients treated with cyclosporine tend to have higher serum creatinine levels than patients treated with azathioprine and steroids (19). This was also observed in our study: Patients treated with azathioprine had a mean serum

creatinine

level

icily, an

with

normal

serum

104

Radiology

#{149}

abnormally

creatinine

in

with who

10.

11.

duced

even

by

a rise

in those high

concentration.

baseline

by aminoglycosides

2.

3.

4.

5.

of transient

Meaney TF, GallagherJH. Use of digital subtraction angiography to assess function. In: Price RR, Rollo FD, Monahan WG, James AE, eds. Digital radiography: a focus on clinical utility. New York: Grune & Stratton, 1982; 235-243. Meaney TF, Weinstein MA, Buonocore E, et al. Digital subtraction angiography of the human cardiovascular system. AIR 1980; 135:1155-1160. Hartmann HG, Braedel HE, Jutzler GA. Detection of renal tubular lesions after abdominal aortography and selective arteriography by quantitative measurements of brush border enzymes in the urine. Nephron 1985; 39:95-101. Skovgaard N, Holm J, Hemmingsen L, Skaarup P. Urinary protein excretion following intravenously administered ionic and non-ionic contrast media in man. Acta Radiol 1989; 30:517-519. Severini G, Aliberti LM. Variation of unnary enzymes N-acetyl-beta-glucosaminidase, alanine-amino-peptidase, and lysozyme in patients receiving radio-contrast

agents. 6.

creatinine 7.

of 8.

Clin Biochem

1987; 20:339-341.

Price RG. Urinary enzymes, nephrotoxicity and renal disease. Toxicology 1982; 23: 99-134. Wellwood JM, Ellis BG, Price RG, Hammond K, Thompson AE, Jones NF. Urinary N-acetyl-beta-D-glucosaminidase activities in patients with renal disease. Br MedJ 1975; 139:408-411. Kunin CM, Chesney RW, Craig WA, England AC, DeAngelis C. Enzymuria as a

studies

in human

kid-

14.

a sensitive 1.

and disease:

jury in experimental animals and renal homograft rejection in man. Ann R Coll Sung EngI 1975; 57:248-261. Tucker SM, Boyd PJR, Thompson AE, Price

with serum

#{149}

injury

13.

12.

in urinary

patients

of renal

neys. In: Fillastre JP, ed. Nephrotoxicity: interaction of drugs with membrane systems mitochondnia-lysosomes. New York: Masson, 1978; 167-174. Burchardt U, Haschen RJ, Krosch H. Clinical usefulness of enzyme determinations in urine. In: Dubach UC, Schmidt U, eds. Diagnostic significance of enzymes and proteins in urine. Bern: Huber, 1979; 106112. Ward J. Gamma-glutamyl-transpeptidase,

References

rise in urine enzyme activity after administration of nonionic contrast material was similar to the pattern of patients

rise

in a transplanted result in nephrotox-

as measured

enzymes,

of 170.12

levels who had undergone transplantation. This same pattern was also seen in healthy subjects in our series, which is in keeping with the results other authors (20).

9.

activ-

high serum creatinine levels were treated with cyclosporine. The level of NAG was least affected, and in all cases the enzyme changes were transient, returning to baseline levels within 72 hours. These data lead us to conclude that DSA performed with a

ture and function kidney does not

Despite the higher mean age of the control patients (55 years) and the increased dose of contrast material pattern

concentra-

enzyme

ity was small, except for the AAP in the group of patients

rial.

the

enzyme

in urinary

single intravenous injection of contrast material to examine renal struc-

p.mol/L and those treated with cyclosporine, 188.14 iimol/L. This observation could lead to the conclusion that inherent nephrotoxicity with cyclosporine is a more likely explanation for the abnormally high baseline enzyme activities and for the increased sensitivity to contrast mate-

administered,

rise

marker

of N-acetyl-beta-glucosaminidase in the general population and in patients with renal disease. Pediatrics 1978; 62:751-760. Adelman RD, Winth F, Rubio T. Fetal and neonatal medicine: a controlled study of the nephrotoxicity of mezlocillin and gentamicin plus ampicillin in the neonate. Pediatr 1987; 111:888-893. Palestine AG, Austin HA, Nussenblatt RB. Clinical studies: renal tubular function in cyclosponine-treated patients. Am J Med 1986; 81:419-424. Mondorf AW, Hendus J, BeienJ, Schenberich JE, Schoeppe W. Tubular toxicity in-

RG.

15.

indicator

Automated

of renal

ischemic

in-

assay of N-acetyl-B-D-

glucosaminidase in normal and pathological urine. Clin Chim Acta 1975; 62:333-339. Kind P. Urinary isoenzymes of N-acetyl-

beta-D glucosaminidase in patients with renal disease, after major surgery and after renal transplantation. Clin Chim Acta 1982; 16.

119:89-97. Jung K, Scholtz

alanine 17.

D.

An optimized

assay

amino

transpeptidase activity Chem 1980; 26:1251-1254.

of

in

urine. Clin Kind P. Corbett CR. Urinary excretion pattern of gamma glutamyl transpeptidase and N-acetyl-beta-glucosaminidase and the validity of relating enzyme activity to urine creatinine concentration. Proceedings of the Tenth International Congress of Clini-

cal Chemistry. Mexico March 3, 1978; 153.

City, February

26 to

18.

Dawson P. Contrast agent ity: an appraisal. Br J Radiol

nephrotoxic1985; 58:121-

19.

Sweny P, HopperJ, Gross M, Varghese Z. Nephrotoxicity of cyclosponine A. Lancet 1981; 1:663. Khoury GA, HopperJC, Varghese Z, et al. Nephrotoxicity of ionic and non-ionic con-

124.

20.

trast material and selective diol

1983;

in digital vascular renal arteriography.

imaging Br J Ra-

56:631-635.

April

1992

Nonionic iodinated contrast media: potential renal damage assessed with enzymuria.

The potential of digital subtraction angiography (DSA) to enable study of the physiology of renal transplantation after a single intravenous injection...
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