Differences in the insulin tolerance test in patients with brain damage depending on posture

Area of Science:

• Endocrinology
• Neurology
• Clinical Diagnostics

Background:

• The insulin tolerance test (ITT) is the standard for diagnosing growth hormone deficiency (GHD) and hypocortisolism.
• Hypopituitarism is common after traumatic brain injury (TBI) and subarachnoid hemorrhage (SAH), increasing ITT use in patients with brain damage.

Purpose of the Study:

• To investigate the effect of patient posture during the ITT on the diagnosis of GHD and hypocortisolism.
• To assess the influence of posture on sympathetic symptoms and test completion in brain-injured patients.

Main Methods:

• A cross-sectional, observational study involving 56 patients (41 TBI, 15 SAH) who underwent the ITT.
• Patients were tested in either a supine (n=38) or sitting (n=18) position.
• Hormonal levels and patient symptoms were recorded.

Main Results:

• Higher rates of hypocortisolism (55.3% vs 0%) and GHD (42.1% vs 11.1%) were diagnosed in the supine position compared to the sitting position.
• Patients in the sitting position experienced more tachycardia (61.1% vs 15.8%) and sweating (66.7% vs 28.9%).
• Somnolence and need for intravenous glucose were significantly reduced in the sitting position (0% vs 66%).

Conclusions:

• Patient posture during the ITT may influence diagnostic rates for GHD and hypocortisolism in brain-injured individuals.
• A sitting position appears to reduce false positive diagnoses and adverse symptoms.
• Further research in a standardized setting is needed to confirm these exploratory findings.