Pathology Handbook

Short Synacthen Stimulation Test

Introduction

Tetracosactrin (Synacthen, Cortrosyn) is a synthetic preparation comprising the first 24 amino acids of ACTH. It stimulates the adrenal cortex to produce cortisol, failure to respond indicating impaired adrenocortical function.

This test is of value in patients with suspected adrenocortical insufficiency eg. Addison's disease and also during the later stages of withdrawal and following total cessation of previous long-term high dose glucocorticoid drug therapy, including topical preparations.

This test can be used either as an in-patient or out-patient screening procedure.

Urgent Results:

If results are required daily then the appropriate arrangements must be made with the Clinical Biochemistry Department beforehand.

Precautions

Please refer to the Trust's phlebotomy procedure for sample collection precautions.

Caution: withdrawal of glucocorticoids may be dangerous. (Pharmacological doses of glucocorticoids should not have been administered for the previous 12 hours prior to the test).

Allergic reactions to tetracosactrin are a possibility, but rarely occur.

Patient preparation

This test is best performed early in the morning. The patient is placed in a reclining position to rest for 30 minutes prior to the test. Smoking is not permitted. Pharmacological doses of glucocorticoids should not have been administered for the previous 12 hours.

Protocol

1

Take basal venous blood sample (6ml SST tube - yellow top).

2

250ug of Tetracosactrin dissolved in about 1ml of sterile water or isotonic saline is administered intramuscularly. (Tetracosactrin is marketed as Synacthen (Ciba) for Cortrosyn (Organon)).

3

After 30 minutes a further blood sample is taken (6ml SST tube - yellow top).

Label the samples with patient details and actual time taken. When test is complete, send request form and samples to the Clinical Biochemistry Department as soon as possible.

Interpretation

Normal response: The 30 minutes sample should show a cortisol level >600 nmol/l.

Failure to meet the normal criteria indicates adrenocortical insufficiency due to any cause. Low normal levels or partial responses are compatible with some degree of adrenocortical impairment and are an indication for further investigation ie. prolonged  5 day Tetracosactrin stimulation test. A clearly normal response excludes primary and secondary adrenocortical insufficiency and indicates that further tests are not required.