Dexamethasone suppression test used to detect the

KGMU 2024

Psychiatric Nursing

Easy

Appeared in: KGMU 2024

Explanation

The Dexamethasone Suppression Test (DST) is used to identify dysregulation of the Hypothalamic-Pituitary-Adrenal (HPA) axis, a biological finding sometimes associated with severe, melancholic depression.
In affected individuals, the administration of dexamethasone fails to suppress the body's natural cortisol production, indicating a faulty negative feedback mechanism within the HPA axis.
This non-suppression of cortisol is considered a positive test result and is more commonly found in endogenous depression compared to other psychiatric conditions.

Option A: Although some patients with schizophrenia may show abnormal DST results, it is not a reliable or standard diagnostic marker for the disorder.
Option C: While HPA axis dysfunction can be present in some forms of dementia, the DST is not a standard or specific test used for its diagnosis.
Option D: Acute stress causes a temporary and normal elevation in cortisol. The DST is designed to test for a pathological failure of the HPA feedback loop, not the physiological presence of a stress response.

Visual 1: Flowchart: Illustrating the Hypothalamic-Pituitary-Adrenal (HPA) axis feedback loop. The visual should show how dexamethasone administration normally suppresses cortisol and how this suppression fails in conditions like major depression.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Diagnostic application of the Dexamethasone Suppression Test (DST) as background academic context rather than a clinical decision trigger.
While historically significant, the DST has low sensitivity and specificity for depression and is no longer in routine clinical use for this purpose, now being considered more of a research tool in psychiatry.
A positive DST result is not exclusive to depression. It can also occur in other conditions like Cushing's syndrome, alcoholism, and eating disorders, highlighting the need for thorough clinical correlation.
What if? If a patient being evaluated for depression has a positive DST but also presents with central obesity, a 'moon face,' and purple striae, the nurse should recognize these as classic signs of Cushing's syndrome. This would be a more likely underlying diagnosis, and the nurse should ensure this is communicated to the medical team for endocrine evaluation.

How to Approach the Question

This is a factual recall question. First, identify the core concept being tested: the purpose of the Dexamethasone Suppression Test.
Recall the physiological mechanism of the test. It assesses the Hypothalamic-Pituitary-Adrenal (HPA) axis by attempting to suppress cortisol production.
Connect this mechanism to its known psychiatric associations. The most classic (though now largely historical) link for the DST is with endogenous or melancholic depression.
Evaluate the given options. Schizophrenia, dementia, and general stress are less specific or incorrect applications for this particular test, making Depression the best-supported answer.

Concept Tested & Keywords

Concept Tested: Diagnostic application of the Dexamethasone Suppression Test (DST)
Stem keywords: Dexamethasone suppression test, detect
Lead-in keywords: BEST, MOST RELEVANT CLUE
Negative lead-in flag: false

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