The influence of ACTH on blood coagulation

Adrenocorticotropic hormone (ACTH), also known as corticotropin, is a
polypeptide tropic hormone secreted by the anterior pituitary gland. It is an
important component of the hypothalamic-pituitary-adrenal (HPA) axis and its
principal effects are increased production and release of cortisol from the
adrenal cortex (1).

ACTH is most commonly used for diagnosing adrenal insufficiency. The
therapeutic use of ACTH is still under investigation. It is used as a treatment
for infantile spasms (West syndrome) (2). The use of ACTH for the treatment of
shock conditions and of respiratory and cardiocirculatory insufficiencies has
been the subject of extended examination. Studies have shown the potential
usefulness of ACTH as first-aid treatment in cases of severe blood losses
(3-5). Recently, it was discovered that ACTH and melanocyte-stimulating
hormones, collectively called melanocortin peptides, together have multiple
effects on the host. Activation of melanocortin receptors, found in many
different cell types, could be a novel strategy to control inflammation.(6)
Whether activation of these receptors could influence the hemostatic system is
however not known.

Ever since the early 1950*s, several studies have focused on the relation
between ACTH and the coagulation system and the possible therapeutic use of
ACTH in surgery. Reports on the effect of ACTH on the haemostatic system,
however, are conflicting. In in vivo studies several coagulation abnormalities
have been reported after administration of ACTH. Two studies found a temporary
thrombocytosis both in normal and in thrombopenic subjects after administration
of ACTH (7; 8). Cosgriff et al, found a shortening of the venous clotting time
suggesting a state of hypercoagulability (9). Smith et al, on the contrary,
found prolongation of the venous clotting time (10). In a study performed by
Chatterjea an increased incidence of thromboembolic compications during ACTH
and cortisone therapy was found and a higher dosage of anticoagulants was
needed to obtain plasma prothrombin activity at the optimum level (11).
Mc Graw et al suggested a differential effect of ACTH on blood clotting: in the
right dose a hypocoagulable state was observed, with a dramatic improvement in
signs and symptoms and the favourable changes in the prothrombin times and
heparin levels, whereas a hypercoagulable state was found after administration
of massive doses or sudden withdrawal. They would possibly implicate the
therapeutic use of ACTH in the acute phase of a phlebothrombosis but also state
the potential danger that ACTH may finally induce a prothrombotic state (12).

Chronic endogenous and exogenous hypercortisolism are known to induce a
hypercoagulable state (13). In Cushing*s syndrome a higher incidence of venous
thromboembolic events was found (14). Therefore, it remains uncertain whether
the coagulation abnormalities found in the studies mentioned can be attributed
to the direct effect of ACTH or to an increased level of cortisol produced by
the adrenal gland following ACTH administration. Hutton et al found a decrease
in platelet aggregability after an intramuscular injection of tetracosactrin
(1-24 ACTH) with a rise in plasma cortisol concentration. Intravenous injection
of hydrocortisone however, had no effect on platelet aggregation (15). Fahey
failed to detect any significant alteration of the coagulation time after
injection of ACTH in normal human subjects or in patients with hypo-or
hyperadrenocortisism (16).

Most published studies have important methodological drawbacks. Lack of a
control group, small study size, and (at this moment) obsolete laboratory
assays obscure the real in vivo effects of administrated ACTH on the
haemostatic system.
Also, none of these studies have shown direct activation of coagulation or
inhibition of fibrinolysis despite the individual haemostatic changes observed
after administration of ACTH. As such, studies including measurements of
endogenous thrombin generation and overall fibrinolytic activity (prothrombin
fragment 1+2, thrombin generation test, plasmin-antiplasmin complex) are needed
to clarify the suggestion of a hypercoagulable and hypofibrinolytic state after
administration of ACTH. Moreover, better differentiation between the separate
effects of ACTH and cortisol is needed. Therefore, the aim of this study is to
determine the effect of ACTH on the activation of coagulation and inhibition of
fibrinolysis by performing short ACTH stimulation tests in patients with
primary adrenal insufficiency.

The primary objective of this clinical controlled trial is to define the
overall effect of adenocorticotropic hormone on coagulation parameters in
patients with primary adrenal insufficiency (as diagnosed by their physician by
previous short ACTH stimulation tests showing no rise in cortisol after
injection with Synacthen) without the obscuring effects of endogenous
corticosteroid excretion.

Secondary objectives
To define the specific effect of ACTH on each of the following coagulation and
fibrinolytic parameters:
1) Prothrombin fragment 1+2 (F1+2)
2) Von Willebrand factor antigen (vWfAg)
3) D-dimer
4) Prothrombin time (PT)
5) Activated partial thromboplastin time (aPTT)
6) von Willebrand factor ristocetin cofactor activity
7) factor VIII:C
8) Plasmin-antiplasmin complex (PAP)
9) Thrombin generation test (ETP)

Phase 1: pilot study
Phase 2: clinical controlled trial

Study design
Phase 1: We will first carry out a pilot study in which we will perform a short
ACTH stimulation test in 10 patients who are planned for this test in their
diagnostic process for the outpatient clinic. We will strive to include 10
patients with a normal rise in cortisol after injection with Synacthen,
therefore patients found to have an abnormal rise in cortisol will not be
included for the final analysis in this pilot study. Ten healthy volunteers
will serve as controls and will be injected with 1 ml saline solution instead
of 1 ml (250 µg/ml) tetracosactide (Synacthen). The volunteers will be
recruited through advertisements and carefully screened before enrolment. A
venflon for intravenous access will be placed once, 30 minutes before first
blood withdrawal, and will be kept in place for blood withdrawal and Synacthen
administration for the entire duration of this study.
If we indeed find significant differences in coagulation parameters before
(t=0), 1 hour (t=1), 3 hours (t=3) and 6 hours after the testing after the
injection of Synacthen (t=6), the protocol as described at phase 2 will be put
into operation. Any changes in this protocol will be sent to the METC as
amendment.

Phase 2: This study is a clinical controlled trial in which patients with known
primary adrenal insufficiency (as diagnosed by their physician by previous
short ACTH stimulation tests, showing no rise in cortisol after injection with
Synacthen) will undergo short ACTH stimulation testing in the early morning.
The test will be performed at two times in the study. The first visit the cases
will be asked to normally take in there morning dose of hydrocortisone
substitution therapy. The second visit, at least 30 days after the first visit,
they will be asked not to take their hydrocortisone substitution therapy until
after the short ACTH stimulation test has been performed. Blood will be drawn
as described at phase 1. This way we can determine the effect of ACTH in
patients with hypocortisolism and eucortisolism. The healthy volunteers and
patients with no abnormalities found in the short ACTH stimulation test, as
described at phase 1, will serve as controls.
If we indeed find a patient with primary adrenal insufficiency (no rise in
cortisol after injection of synacthen) at phase 1 of this study, the results of
this patient will be included in phase 2. This patient will be asked to come
back for a second Synacthen test with the normal hydrocortisone substitution.

Phase 1: We will first carry out a pilot study in which we will perform one
short ACTH stimulation test on 10 patients in light of routine laboratory
testing. Ten healthy volunteers will serve as controls and will be injected
with saline solution instead of Synacthen. If we indeed find significant
differences in coagulation parameters before (t=0) and1 hour (t=1), 3 hours
(t=3) and 6 hours after the injection of Synacthen (t=6) compared to the
control group, the protocol as described at phase 2 will be put into operation.
Phase 2: The short ACTH stimulation test will be performed two times. The first
visit the cases will be asked to normally take in there morning dose of
hydrocortisone substitution therapy. The second visit they will be asked to not
take their hydrocortisone substitution therapy until after the short ACTH
stimulation test has been performed. The healthy volunteers and patients with
no abnormalities found in the short ACTH stimulation test, as described at
phase 1, will serve as controls.

Phase 1: the ACTH test is not being performed for this study specifically, the
physician of the outpatient clinic has ordered the test, the only risk related
to this study in this phase is placement of a venflon. If this phase does not
show an influence we will not have to expose patients with an established
adrenal insufficiency to any risk.

Phase 2: As patients with adrenal insufficiency depend on hydrocortisone
substitution therapy, delaying the intake of hydrocortisone until after the
short ACTH stimulation test is performed, implies a small risk of developing
symptoms of cortisol deficiency, and even smaller risk of "adrenal crisis". For
this reason every test will be performed under strict supervision of the
investigator. In case a patient develops symptoms indicating severe adrenal
insufficiency the test will immediately be ceased and an infusion of isotonic
sodium chloride solution will be begun to restore volume deficit and correct
hypotension. We will also immediately start hydrocortison (Solucortef) 100 mg
i.v. bolus followed by 200-500 mg/24h. The patient will be hospitalized until a
stable situation has been reached.