Dexamethasone

Test Code

29391X

Preferred Specimen

0.85 mL serum collected in a red-top tube (no gel)

Minimum Volume

0.25 mL

Instructions

Draw specimen between 8:00 a.m. and 10:00 a.m.

Transport Temperature

Refrigerated (cold packs)

Specimen Stability

Room temperature: 72 hours
Refrigerated: 14 days
Frozen: 90 days

Reject Criteria (Eg, hemolysis? Lipemia? Thaw/Other?)

Gross hemolysis • Grossly lipemic • Serum separator tube (SST)

Methodology
Chromatography/Mass Spectrometry

FDA Status
This test was developed and its analytical performance characteristics have been determined by Quest Diagnostics. It has not been cleared or approved by FDA. This assay has been validated pursuant to the CLIA regulations and is used for clinical purposes.

Setup Schedule

Set up: Mon; Report available: 2-10 days

Clinical Significance

Measurement of Dexamethasone is useful in assuring compliance with Dexamethasone administration and documenting adequate dosing during such procedures as the Dexamethasone Suppression Test used in the differential diagnosis of Cushing's syndrome or screening for hypercortisolism in difficult-to-control Type II Diabetes.

1. Buse JB, Kahn SE, Aroda VR, et al. Prevalence of hypercortisolism in difficult-to-control type 2 diabetes. Diabetes Care. 2025;48(12):2012-2020 doi: 10.2337/dc24-2841
2. DeFronzo RA, Auchus RJ. Cushing Syndrome, hypercortisolism, and glucose homeostasis: a review. Diabetes. 2025;74(12):2168-2178. doi: 10.2337/db25-0120
3. Lundqvist MH, Pereira MJ, Almby K, et al. Regulation of the cortisol axis, glucagon, and growth hormone by glucose is altered in prediabetes and type 2 diabetes. J Clin Endocrinol Metab. 2024;109:e675-e688. doi: 10.1210/clinem/dgad549
4. Nieman LK, Biller BMK, Findling JW, et al. The diagnosis of Cushing's Syndrome: an endocrine society clinical practice guideline. J Clin Endocrinol Metab. 2008; 93: 1526-1540. doi: 10.1210/jc.2008-0125
5. DeFronzo RA, Fonseca V, Aroda VR, et al. Inadequately controlled type 2 diabetes and hypercortisolism: improved glycemia with mifepristone treatment. Diabetes Care. 2025;48(12):2036-2044. doi: 10.2337/dc25-1055

The CPT Codes provided in this document are based on AMA guidelines and are for informational purposes only. CPT coding is the sole responsibility of the billing party. Please direct any questions regarding coding to the payor being billed. Any Profile/panel component may be ordered separately. Reflex tests are performed at an additional charge.