Purpose
To investigate corticotropic function using CRH or CRF (Corticotropin Releasing Factor) or corticoliberin.
Subject preparation
Subject fasting for 12 hours and lying down for 30 minutes.
Product
CRH
Dose
1 µg/kg body weight (do not exceed 75 µg).
Protocol
- The challenge must be administered at 8 a.m.
- Commence the perfusion of normal saline 30 minutes before the challenge.
- Samples (dry tubes for the cortisol and EDTA + aprotinin tubes for the ACTH) at time intervals: – 15 min (T-15) and 0 (T0).
- IV injection of the correct dose of CRH over one minute.
- Samples at time intervals T+15, T+30, T+60 and T+120 min.
Samples
After centrifugation, draw off serum and plasma. Freeze plasma (to be used to assay ACTH) immediately and store serum (to be used to assay cortisol) at +4°C.
Assays
ACTH and cortisol