Debrief: what the evidence supports

Do not treat any specific dose, sampling time, or numeric cutoff shown here as portable to a different assay or laboratory. Every cutoff and interval is local and assay-specific; CLIA requires a laboratory to verify or establish its own reference intervals and performance specifications. A single value or these cases cannot diagnose adrenal insufficiency, Cushing syndrome, hyperprolactinemia, or GH deficiency; that judgment belongs to the ordering clinician, working from the full clinical picture and the local protocol.

Dynamic-test protocols, stability windows, PEG-recovery bands, and reference intervals genuinely vary by laboratory and assay, so a single universal number would be inaccurate for most laboratories.