Neurocritical Care

, Volume 11, Issue 2, pp 158–164

Low-Dose and High-Dose Synacthen Tests and the Hemodynamic Response to Hydrocortisone in Acute Traumatic Brain Injury

  • R. S. Wijesurendra
  • F. Bernard
  • J. Outtrim
  • B. Maiya
  • S. Joshi
  • P. J. Hutchinson
  • D. J. Halsall
  • D. K. Menon
Original Article

Abstract

Introduction

In order to identify whether low-dose (1 μg) tetracosactide (Synacthen®) testing may be preferable to high-dose (250 μg) testing in the diagnosis of adrenal insufficiency in traumatic brain injury (TBI), as suggested by studies in other forms of critical illness.

Methods

We retrospectively reviewed the results of modified tetracosactide tests (involving administration of both low-dose and high-dose tetracosactide) conducted for clinical indications in patients in a neurocritical care unit within 10 days of TBI. Sixty-three modified tests were included and cortisol concentrations before and after administration of tetracosactide were extracted from the hospital records. Data were also extracted regarding hemodynamic response to empirical corticosteroid therapy, based on rapid weaning from vasoactive drugs.

Results

Cortisol increments at 30 and 60 min following tetracosactide correlated well in the low-dose test (r2 = 0.875, P < 0.0001). The mean cortisol concentration was 581 nmol/l at 30 min and 556 nmol/l at 60 min in the low-dose test. Cortisol increments following low-dose and high-dose testing correlated well overall (r2 = 0.839, P < 0.0001), but results were discordant in 27 of 63 cases (43%) when the same diagnostic threshold was used. ROC curve analysis showed that both tests performed poorly in identifying hemodynamic steroid responsiveness (AUC 0.553 and 0.502, respectively).

Conclusions

In the low-dose tetracosactide test, it is sufficient to determine cortisol concentrations at baseline and at 30 min. Low-dose and high-dose tests give discordant results in a significant proportion of cases when using the same diagnostic threshold. Neither test can be used to guide the initiation of corticosteroid therapy in acute TBI.

Keywords

Traumatic brain injury Tetracosactide Synacthen Low-dose Adrenal insufficiency 

Abbreviations

ACTH

Adrenocorticotropin hormone

APACHE

Acute physiology and chronic health evaluation

GCS

Glasgow coma score

HPA

Hypothalamo-pituitary-adrenal

ISS

Injury severity score

ROC

Receiver-operating characteristic

TBI

Traumatic brain injury

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Copyright information

© Humana Press Inc. 2009

Authors and Affiliations

  • R. S. Wijesurendra
    • 1
  • F. Bernard
    • 1
    • 4
  • J. Outtrim
    • 1
  • B. Maiya
    • 1
  • S. Joshi
    • 2
  • P. J. Hutchinson
    • 3
  • D. J. Halsall
    • 2
  • D. K. Menon
    • 1
  1. 1.University Division of AnaesthesiaCambridge University Hospitals NHS Foundation Trust, Addenbrooke’s HospitalCambridgeUK
  2. 2.Department of Clinical BiochemistryCambridge University Hospitals NHS Foundation Trust, Addenbrooke’s HospitalCambridgeUK
  3. 3.University Department of NeurosurgeryCambridge University Hospitals NHS Foundation Trust, Addenbrooke’s HospitalCambridgeUK
  4. 4.University Department of Critical Care Medicine and General Internal MedicineHôpital du Sacré-CœurMontréalCanada

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