Effect of levonorgestrel contraceptive implants, NORPLANT®, on blood coagulation

CONTRACEPTION

EFFECT

OF LEVONORGESTREL NORPLANT’=,

M.M.

Shaabanl+*, Sohair

Departments Pathology*,

of

Sawsan A.

CONTRACEPTIVE

IMPLANTS,

ON BLOOD COAGULATION

FarghalyZ

I.

Elwar?, and

M.Y.

Nabila

El-Kabsh*,

Thabet*

Obstetrics and Gynecology1 Faculty of Medicine, Assiut P. 0. Box 30, Assiut, Egypt

and Clinical University,

Abstract A longitudinal study of coagulation parameters was carried out on 47 women using the levonorgestrel subdermal implants, NORPLANT@. The study comprised measurement of platelet count, prothrombin time, thrombin time, partial thromboplastin time with kaolin, clotting factors I, II, V and VI through XIII, plasminogen, antithrombin III (AT III), al antitrypsin, a2 macroglobulin and fibrinogen degradation products. The tests were done at admission and after one, three and six months of NORPLANT@ use. Parallel and similar studies were done on two groups of oral contraceptive users; the first group used a pill containing 1 mg norethisterone and 50 pg mestranol! and the second a pill consisting of 150 pg levonorgestrel and 30 ug ethinylestradiol. Results from this ongoing study have indicated that women using NORPLANT” implants evidenced lack of effects on most of the parameters tested except for factor VII activity which was increased and AT III concentration which was decreased after six months of use. The combined pill users evidenced marked changes in the platelet count, the screening tests and in most of the changes were apparent after three the coagulation-promoting factors; months of use and became more pronounced after six months. The results demonstrate, that the implants had less pronounced with marked contrast, effects on the blood coagulation system than did the combined pills used in

this

study.

Submitted Accepted

*

for publication for publication

NORPLANT” is contraceptive

**

5, 26,

1984 1984

the Population Council’s subdermal implants.

To whom correspondence

NOVEMBER

October October

should

1984 VOL. 30 NO. 5

be

registered

trademark

for

addressed

421

CONTRACEPTION Introduction Epidemiological studies have indicated that users of combined contraceptive pills (OC) stand a slightly but significantly increased risk of in thromboembolism, and that this risk is related to the dose of estrogen These observations were supported by laboratory findings of the OC (1). changes in different coagulation and fibrinolytic parameters in users of The effect of progestogens on the coagulation these contraceptives (2,3). system seems to be minimal (41, but cannot be ruled out completely (5,6). There is paucity of information in this respect about the progestogen norgestrel which is now contained in many hormonal contraceptive systems. The NORPLANT” system has recently been introduced for long-term contraception and depends upon the release of levonorgestrel from subdermally The present investigation is a longitudinal placed Silastic” capsules. study of the effect of this contraceptive upon various blood coagulation parameters. For the sake of comparing the effects of NORPLANT@’ implants with those which have been described for combination contraceptive pills, parallel studies were conducted on two groups of women using oral one group used a regular-dose combined pill containing contraception; norethisterone, and the other used a low-dose combined pill containing levonorgestrel. Material

and Methods

One-hundred-and-two women were recruited for this study from among the attendees of the Family Planning Clinic of the Assiut University Hospital. They belonged to the lower socio-economic group and were all parous but not breast-feeding. All were non-smokers and were clinically healthy. They were not diabetic or hypertensive and had no history of thromboembolic or hepatic disease or abnormal genital or extragenital bleeding. They had not used any hormonal contraception for at least three months before admission to the study. They comprised 47 women who used NORPLANT@ implants and 55 Twenty-five of the latter who used oral combined contraceptive pills. group used a pill containing 1 mg norethisterone (NET) and 50 pg mestranol (MS) (Norinyl/SO, Syntex) and 30 used a pill containing 150 pg levoThe norgestrel (LNG) and 30 pg ethinylestradiol (EE) (Nordette, Wyeth). NORPLANT@ group had a mean parity of 5.6 (range: 3-11) and a mean age of The OC group had a mean parity of 3.4 (range: 32.8 years (range: 25-40). I-8) and a mean age of 27.2 years (range: 20-35). Clinical assessment and blood sampling for the study were done at admission and after one, three NORPLANT@ insertion was done during and six months of contraceptive use. the first eight days of the menstrual cycle and was always made under the skin of the left upper arm; the blood samples were taken from the right arm. The

to

were always rested for 15 minutes before venipuncture. This was the morning, and 20 ml of blood were withdrawn in a plastic The sample was divided into four fractions. The first was added The second was added to sodium and used for platelet counts. buffer and immediately centrifuged at 4°C at 3000 rpm for ten

women

done in syringe. EDTA

citrate

422

NOVEMBER

1984VOL.30NO.S

CONTRACEPTION

minutes. The separated plasma was used for measurement of prothrombin time (PT), thrombin time (TT), partial thromboplastin time with kaolin (PTT-K) and clotting factors I, II, V, and VII through XII. Measurements of factor VII, PT and PTT were carried out within 30 minutes from blood withdrawal; the rest of the tests were done within two hours. A third fraction of 4.5 ml blood was added to 0.5 ml citrate buffer and 0.1 ml aprotinin in a plastic tube and centrifuged as described above. This plasma which was intended for assay of factor XIII activity was kept frozen until processed (usually within four months). The rest of the blood sample was left to clot at 37”C, and the serum separated was used for estimation of fibrinogen degradation products (FDP), plaaminogen, antithrombin III !AT III), al antitrypain (al-AT) and a2 macroglobulin (a2-MG). The overall screening teats: PT, Direct platelet count was performed (7). TT and PTT-K, were measured by the methods described by Bigga (8). The coagulation factor assays performed were factor I measurement (9) and estimation of the activity of factors II and V (IO), factor VII (II), factors VIII and IX (121, factor X (13), factor XI and XII (14) and factor These assays were made with kits purchased from Behringwerke XIII (15). (West Germany) using an automatic end-point fibrometer purchased from Biomerieux Laboratories, Ltd. (France). Plaaminogen, AT III, al-AT and ag-MG were measured by single radial immunodiffuaidn (16) using chemicals FDP were assayed with a kit obtained from the obtained from Behringwerke. same source a method dependent on the clumping of certain using staphylococcus strains by serum containing FDPs (17). Quantities of the reagents auffic’ient for the study were purchased in large single lots. Control Plasma-N (Behringwerke Code Number ORKE 13) was used for accuracy control of the one-stage PT using Thromborel@, TT using Teat Thrombin and and fibrinogen determinations. The interassay PTT-K using Pathromtine coefficients of variability for the four teats were, respectively, 5.‘2%, 10.2X, 5.2?; and 5.2%. A standard human plasma (Behringwerke Code Number ORKL 07) was used for constructing the reference curves used in the determinations of the activities of factors II, V, VII, VIII, IX, X, XI and XII. An aliquot of a batch of pathological plasma (Behringwerke, Pathoplaama@ II, Code Number OTXL 11) was incorporated in the assays of factors II, VII and X activity. This pathological plasma was prepared from and the activity of these a pool of plasma from selected healthy donors, three factors was diminished by special procedure. The interassay VII and X activity were, coefficients of variability for factor II, respectively, 9.1X, 7.1% and 9.7%. The changes in the various coagulation parameters during contraceptive use were statistically evaluated by the paired t teat using the admission The one-month follow-up values of the same subjects as baselines. laboratory teats were skipped in the pill-using groups in an effort to However, the drop-out rate in pill diminish the subjects’ inconvenience. users was high.

NOVEMBER

1984 VOL

30 NO. 5

423

CONTRACEPTION

Results Table

I

gives

the

values

of

the

broad-spectrum

the individual clotting, Fibrinolytic before and during NORPLANT@ Implant use. count or the three plasma clotting times:

plasma

clotting

times

and

of

and antlthrombin Factors measured There were no changes in platelet PT, TP and PTT-K. The levels of

individual Factors showed some changes that did not attain statistical significance except For Factor VII activity which significantly increased and AT III concentration which significantly decreased after 6 months From NORPLANT@’ insertion. The other antithrombrns, ,I-AT and a2-MG, did not change. Testing For FDP consistently yielded negative results (indicating values
Discussion The coagulation system is composed of two systems: the clotting system which leads to the Formation of Fibrin, and the Fibrinolytic system which leads to its dissolution. The Formation of Fibrin is dependent on Formation of thrombin From prothrombin. The latter conversion is enhanced by several clotting Factors and inhibited by a number of antithrombins. Fibrinolysis is initiated when plasminogen is converted to plasmin, a process that has its activating Factors and inhibiting antiplasmins. This simplistic description of coagulation indicates how difficult it is to be comprehensive in evaluating this system. Even at this time, there is no laboratory test or combination of tests that will, with accuracy, reliability and specificity, predict whether under certain circumstances a patient will develop a thromboembolic event or not (18). The present study used 20 tests to look at different aspects of the process, but it Falls short of being comprehensive. On the whole, the changes in the various parameters tested were less marked in the NORPLANT@ group than in the two contraceptive pill groups. However, there was a significant increase in the activity of Factor VII and a decrease in AT III concentration after six months of implant use. Factor VII is important in initiation of the extrinsic pathway of clotting by complexing with a certain tissue Factor. Under pathologic conditions,

424

NOVEMBER

1984 VOL. 30 NO. 5

(set)

(set)

106/dL)

thromboplastin

time

XIII

Factor

III

P

** = p<.o1,4***=

.OOl

(mg/dl)

o(2 Macroglobulin

(mg/dl)

(mg/dl)

(mg/dl)

%

%

o(, Antitrypsin

Antithrombin

Plasminogen

XII

Factor

%

XI %

Factor

%

IX 9,

VIII

Factor

X 8

VII

Factor

Factor

V %

Factor

Factor

II %

Factor

(mg/dl)

(set)

Fibrinogen

time

Partial

Thrombin

(X

I: Coagulation

time

Count

Prothrombin

Platelet

Table

+ _ + -

13.9 20.3

2.2

1.0

48

_+ + + -+ -+ + + _ + _ -+ _+ -+ _+

102 81 104 100 93 102 97 98 15.7 17.2 382 256

91

169

4.7

5.3

16

16

14

19

t test

-2

+

25

-0.26

+:.01

+0.49

+2.36

+2.12

+4.29

-0.52

-0.79

15

-1.0

17

-0.69

_+

+ -

_+

_+

_+

+ _

-+

_+

_+

-+

-+

-+

_+

-+

-3.21 +0.86

+ -

-+

-+

+ _

+0.23

-0.05

-0.18

i3.2

n=42-

l-Month Change +

24

14

13

Paired

-+

114

41.9 + 3.7 350 _ + 63

-+

262

Admission Level + SD n-= 47

FROM

CHANGES

63

152

4.89

6.10

10.5

9.8

15.6

20.9

16.3

20.7

27.9

11.5

17.3

64.0

2.3

0.73

-3

+

24

+1.6

+0.3

+0.6

+2.7

-0.2

+2.8

+1.0

+0.2

+2.0

-0.5

+2.4

+2.98

-0.15

-0.61

-0.27

+0.4

2.37

2.10

0.91

27

SD

_f

-+

+ _

+

70

154

4.9

4.1

+19.6 _

+18.4 -

+14.9 _

+19.1 -

_+16.9

-+11.6

-+30.5

_+16.4

+14.5 -

+54.7 _

_+

-+

+ -

_+

Change + n= 43-

3-Month

2.6

+ 57 - 12

- 2.6

- 2.2

+ 4.2

f 4.6

+ 2.0

+ 5.0

+ 5.2

+ 3.8

+10.1

+ 3.4

+ 6.6

_ + 17.7 + 7.7 + 4.8*** + 148 + 61

_ + 20.5

+ 24.5 + _ 17.0

+ 13.7 _ + 16.2 _

_ + 23.3**

+ 19.6 + - 15.6

- 1.71 _ + 2.61 +10.91 + 46.0

- 0.71 +

+ 37 - 0.23 + 1.40

+18.2

6-Month Change + SD n= 45-

NORPLANT (R) Implants

0.48

21.2

SD

Using

ADMISSION

in Women

Studies

=s

z

z

3

8

time

V %

VII

VIII

IX %

X %

XI %

XII

XIII

Factor

Factor

Factor

Factor

Factor

Factor

Factor

Factor

%

%

III

*= P<.O5,

(mg/dL)

**= Pl.01,

QI2 Macroglobulin

(mg/dL)

(mg/dL)

(mg/dL)

%

%

Antitrypsin

Antithrombin

Plasminogen

II %

Factor

q,

(set)

(set)

(mg/dL)

(see)

***=

Studies

(X 106/dL)

time

thromboplastin

Fibrinogen

time

Partial

Thrombin

Prothrombin

Count

II: Coagulation

Platelet

Table

P(.OOl

+ -

250

91

_+ 36

391

5.9

+

20.1

12

_+ 4.9

-+

102

35

16.3

_+

107

91 _+ 23

99 _ + 12 89 + _ 12

75 _ + 19 94 _ + 10

114 _ + 10 96 _ + 20

38.9 -+3.8 358 + 59

257 -+ 55 13.49+0.8 19.9 +2.8

Admission Level + SD n= 25

CHANGES

in Women

NET

1 mg/MS

+ -

-

+34.3** _ _+29.5** +15.2*** _

+29.8 +24.3

9.0

5.1

3.8

_+ 5 _+

41+88 _

t test

__

39

7.9

1.8

-+30.7 -+13.7***

-+30.6

0.83+ - 2.7

-

+15.9

+

+

+39.8

+

-+23.6 -+33.2***

_+14.2***

+14.1

+16.0

-+28.3**

1.9

+23.3

-

2.5

1.5**

50***

-+ 2.1**

-+

0.3

+ _

40

- 0.8

+ 1.9***

-+22.8** +19.6*** _ _+14.4*** -+39.1* +26.8*** -

+20.1 +48.3

+23.6

-+ _+

1.1

-

- 4.1 36

18 +

+

39

_f 72

5.7*

2.8

+29.7** +14.8** -

+23.3 +23.2

-+20.4

+12.1

+59.7

+28.4

_+17.1***

+20.7

+43.9*** _

-+

0.5***

-+ 2.6***

-

+ _

-+ 46***

- 2.8

3.1

-

+51.7

57 1.5

+

6-Month Change + SD n= 15

50 ug Contraceptive

3-Month Change + SD n= 18

ADMISSION

Paired

FROM

Using

Pill

VI

thromboplastin

(set)

-+ + _ _+ +

+ 91 ._

101 16.7 24.1 454 296

XIII

Factor

*= P<.OS,

~~~ ____

(mg/dL)

**= P(.Ol,

o(2 Macroglobulin

(mg/dL)

(mg/dL)

III

(mg/dL)

o(, Antitrypsin

Antithrombin

***=

+ _

94

XII

Plasminogen

+ _

96

XI %

Factor

Factor

%

+ _

96

%

_+

100

IX %

X%

+ -

Factor

+ -

86 101

Factor

%

VIII

8

VII

14

P<.OUl

190

10.1

5

16

16

26

9

16

19

26

18

Factor

_+

Factor

-+

100

IT %

113

4.1 69

V %

+ _

1.1 2.1

Factor

+ _

354

_+

41.7

-+

13.7 20.3

48

Factor

(mg/dL)

-+

258

-+17.8*** _+16.2

+

2.8 2.8 45 4

+

-+

_+

+ _

-+

+ _

20

99

6.1

5.0*

9.9*

-+11.1

t test

5.0 6.1

+

_+41.0 +

-+19.4** 5.2

+

+17.3* -

+17.1

+10.5

4.9

+24.6

6.9***

_+15.8**

+10.9

6.9

_+

3.7***

0.7***

1.2*

43

+

-+

-+

-+

-+

_+15.7***

1.8

0.6

0.6

16

+15.8

-

-

-

+

n= IV

+

3-Month Change

SD

150 ug/EE

ADMISSION

LNG

Paired

FROM

Using

CHANGES

in Women

Admission Level + SD n= 30

Studies

(X 106/dL)

time (set)

time

(set)

Fibrinogen

time

Partial

Thrombin

Prothrombin

Count

III: Coagulation

Platelet

Table

+10.5*** __ +17.0** -.

+16.6** _ +10.6*** -

:12.3"** +38.8* _

-

-

72 _ + 140 f50+121 -

- 3.5 _ + 5.1 - 6.9 _ + 8.4**

+13.7

+14.8

+25.4

+41.1

50 _ +16.9*** + 6.6 _ +19.5 +24.4 +13.4***

+

+16.3

+12.1

- 3.5 _ + 2.3**" +45.3 +37.6***

- 1.8 + l.l**

43 _ + 40*** - 1.8 + 0.7***

+

6-Month Change + SD n= IS

30 ug Contraceptive

Pill

CONTRACEPTION

tissue factor might come from atheromatous lesions factor VII-tissue complex activates factor X, “autocatalytic” reactions (19).

or from blood cells. The initiating a number of

Antithrombin III is the most effective of the antithrombins. Some combined OCs were found to have a definite effect in reducing AT III (19,20), while others did not show this effect (3). It would seem that this difference can be explained by the type and dosage of the steroids in the combination. However, it is most difficult to interpret altered antithrombin levels as indicative of a “prethrombotic” state unless they fall in the range found in states of congential deficiency of this factor, which is 40% to 55X of the normal values (20). In the present study, the levels of the other antithrombins, al-AT and (x2-MG, were not signficantly altered by NORPLANT” use. It was difficult for us to recruit women for a longitudinal study on OCs entailing repeated blood sampling and to keep them in the study. However, in spite of the high dropout rate, the results have shown that the effects of OCs on blood coagulation and fibrinolytic parameters in Egyptian women are similar to those reported for Caucasian women (2,3), but due to these constraints our results in the OC group do not permit us to draw final conclusions as regards the effects of these contraceptives on blood coagulation in our community. Further efforts, on both the laboratory and epidemiological sides, are required. However, it must be pointed out that women on LNG 150 ug/EE 30 ug evidenced less pronounced changes in some blood coagulation parameters than those that developed in women on NET 1 mg/MS 50 pg. It can be concluded from the present work that the balance of evidence points to a relative lack of effect of NORPLANT” implants on the blood coagulation/fibrinolytic system. Undoubtedly, the absence of estrogen and the small dose of the progestogen delivered to the body from the implants (approximately 30 pg per day) have contributed to this benign outcome. The effect on factor VII and antithrombin III as well as on the other blood clotting parameters will need further follow-up; NORPLANT @ is a system intended for five-year use.

Acknowledgement This

428

study

was supported

by Rockefeller

Foundation

Grant

NOVEMBER

No. 80008.

1984VOL.30NO.5

CONTRACEPTION

References Royal

1.

College

Health: New York,

A

of

General

Preliminary

Practitioners: Pitman

Oral contraceptives, Poller, L.: Med. Bult. 34:151, 1978.

3.

Notelovitz, M., Kitchens, C.S., Coone, Low-dose oral contraceptive usage and Gynecol. 141:71-75, 1981.

4.

Poller, L., Thomson, J.M., Thomas, W. and platelet aggregation during oral 8r. Med. J. 27:705, follow-up study. Margulis, R.R., tional agents 93:161-166,

blood

clotting

and

L, McKenzie, coagulation.

thrombosis.

L.

and Am.

Rr.

Carter, R.: J. Obstet.

and Wray, C.: Blood clotting progestogen contraception: 1971.

Ambrus, J.L., Mink, I. and and blood coagulation.

Stryker, Am. J.

A

J.: ProgestaObstet. Gynecol.

1965. Blood coagulation and fibrinolytic and Borges, R.F.: during cyclic and continuous application of progestaAm. J. Obstet. Gynecol. 97:448-459, 1967.

6.

F.K. Belier, enzyme studies tional agents.

7.

Dacie, J.V. and & A. Churchill,

8.

Biggs, R.: Thrombosis, p. 609.

9.

Ratnoff,

Lewis, S.M.: Ltd., London,

Practical 1975.

Haematology,

Appendix 2, Human Blood Coagulation, Blackwell Scientific First Edition.

O.D.

and

Menzie, Clin.

C.:

A new

method

Med.

37:316,

1951.

for

J. Lab.

10.

Deutsch, E.: Normal werke 1969.

In: E. Dutsch, U. und interpretation.

11.

Poller, L., Thomson, J.M., Sear, C.H.J. tion of a congenital defect of factor VII The clinical use of the plasma. J. Clin.

12.

Hardisty, R.M. and Management.

13.

The specific assay of Power-Stuart Denson, K.W.E.: Acta Hematolitica 25:105, 1961. VII.

14.

The Contact Phase Nossel, H.L.: Scientific Publications, Oxford,

and Ingram, Blackwell

G. Geyer, Verlag

Fifth

Edition.

J.

Haemostasis and Publications, 1972,

fibrinogen.

NOVEMBER

and ILtd.,

1974.

2.

5.

Oral Contraceptives Medical Publishing Co.,

Report.

the

determination

of

Laboratoriums diagnostik, August-Steinkpot, Berlin,

and Thomas, W.: Identificain a colony of beagle dogs: Path. 24:626-1979.

G.I.C.: Bleeding Disorders: Investigation Scientific Publications, Oxford, 1965.

1984 VOL. 30 NO. 5

of Blood 1964.

Coagulation.

factor

and

factor

Blackwell

429

CONTRACEPTION

15.

Losowsky, M.S., Hall, R. and Goldie, W.: Congenital deficiency fibrin stabilising factor. Lancet July 2:156, 1965.

16.

Mancini, G., Carbonara, A.O. and Heremans, J.F.: Immunological quantitation of antigens by single radial immunodiffusion. Immunochemistry 2:235, 1965.

17.

Hawiger, J., Niewiarowski, S., Gurewich, V. and Thomas, D.P.: Measurement of fibrinogen and fibrin degradation products in serum by staphylococcal clumping test. J. Lab. Clin. Med. 75:93, 1970.

18.

Hirsh, J.: thrombosis.

19.

MacFarlane, R.G.: An enzyme cascade in the blood clotting mechanism Nature 202:498, 1964. and its function as a biochemical amplifier.

20.

C.R.M., Horne, C.H.W. and Howie, P.W., Mallison, A.C., Prentice, McNicol, G.P.: Effect of combined oestrogen-progestogen oral oestrogen and progestogen on antiplasmin and contraceptives, antithrombin activity. Lancet December ‘2:1329, 1970.

21.

Von Kaulla, F., Droegemueller, W., Aoki, N. and von Kaulla, K.N.: Antithrombin III depression and thrombin generation acceleration Am. J. Obstet. Gynecol. in women taking oral contraceptives. 109:868, 1971.

430

Blood tests for the diagnosis Blood 57:1, 1981.

of

of venous and arterial

NOVEMBER 1984 VOL. 30 NO. 5