Category
SPECIAL CHEMISTRY.
Sub Category
ENDOCRINE
Synonyms/Aliases
DST SINGLE DOSE OVERNIGHT, CORTISOL
Abbreviations
1MG OVERNIGHT DST, CORTISOL
Type
PROFILE/ PANEL (BUNDLED TESTS)
Results
RESULTS READY/ REPORTED 7 WORKING DAYS
Method
IMMUNOASSAY
Temp
REFRIGERATED OR FROZEN.
Setup
BATCHED.
Components Parameters
BASAL (PRE-DEXAMETHASONE) 8AM & POST DEXAMETHASONE 8AM CORTISOL LEVELS.
PRE-ANALYTIC CONSIDERATIONS
Test Ordering Instructions
FILL OUT TEST REQUEST FORM FULLY & LEGIBLY. MULTI-SAMPLING WILL BE DONE. SPECIFY EXACT DEXAMETHASONE SUPPRESSION TEST (VARIATIONS CAN OCCUR E.G. LOW DOSE 48-HOUR DST; HIGH DOSE 48-HOUR DST; SIMILAR TESTS MAY ALSO BE PERFORMED FOR A DIFFERENT ANALYTE I.E. ACTH). PROVIDE CLINICAL HISTORY. PRESCRIBE DEXAMETHASONE I.E. 1 MG FOR ADULTS; 0.3MG/M2 FOR CHILDREN.
Patient preparation
COLLECTION OF SAMPLES BEFORE & AFTER ADMINISTRATION OF DEXAMETHASONE IS DONE. IF THERE IS A CONCURRENT ORDER FOR 24 HOUR URINE CORTISOL LEVEL, THE COLLECTION OF 24 HOUR URINE MUST BE DONE PRIOR TO COMMENCING THIS TEST. A BASAL (PRE-DEXAMETHASONE) SAMPLE IS COLLECTED AT 8-9A.M. ON DAY 1. AT NIGHT (11P.M.-MIDNIGHT), THE PATIENT WILL TAKE THE PRESCRIBED DEXAMETHASONE. AT 8A.M. ON DAY 2, PATIENT WILL PRESENT HIMSELF FOR COLLECTION OF THE POST-DEXAMETHASONE SAMPLE.
Sample type
TWO SERUM SAMPLES [BASAL (PRE-DEXAMETHASONE; COLLECTED AT 8-9A.M. ON DAY 1) AND POST-DEXAMETHASONE (COLLECTED AT 8-9A.M. ON DAY 2 AFTER INGESTION OF DEXAMETHASONE BETWEEN 11P.M. AND MIDNIGHT)]. SAMPLE LABEL MUST INCLUDE COLLECTION SEQUENCE I.E. BASAL (PRE-DEXAMETHASONE) & POST-DEXAMETHASONE.
Container/ preservative
THREE SERUM SEPARATOR TUBES (SST/ GEL) OR PLAIN (RED TOP) VACUTAINERS.
Sample volume
AT LEAST 3 ML
Rejection criteria
LABELING ISSUE (UNLABELED/ MISLABELED/ COLLECTION SEQUENCE NOT STATED); MISSING REQUEST FORM; MISMATCH BETWEEN REQUEST FORM & SAMPLE DETAILS; MISSING AGE/ GENDER; WRONG SAMPLE TYPE; INSUFFICIENT SAMPLE.
Other Instructions
CENTRIFUGE SST (SERUM GEL TUBES) WITHIN 1-2 HOURS OF COLLECTION. CENTRIFUGE RED TOP VACUTAINERS AND ALIQUOT SERUM WITHIN 1-2 HOURS OF COLLECTION. THE SEPARATION VIAL MUST BE LABELED WITH AT LEAST 2 PATIENT IDENTIFIERS AND THE SAMPLE TYPE. WHERE MULTIPLE CORTISOL TESTS ARE CONCURRENTLY ORDERED I.E. A.M. CORTISOL, P.M. CORTISOL, 24 HOUR URINE CORTISOL & OVERNIGHT DST, PLEASE CONTACT THE PATHOLOGIST FOR CORRECT INSTRUCTIONS & COLLECTION SEQUENCE TO AVOID REPEAT COLLECTIONS &/ OR COMPROMISED RESULTS.
Reference intervals
INTERPRETIVE DATA IS PROVIDED ON THE REPORT.
Clinical Utility
THIS IS AN ENDOCRINE SUPPRESSION TEST USED WHEN SCREENING FOR CUSHING'S DISEASE OR CUSHING'S SYNDROME (HYPERSECRETION OF CORTISOL).
Test Limitations/ Confounders
INCORRECT LABELING OF COLLECTION SEQUENCE WILL RESULT IN INACCURATE INTERPRETATION. FALSE POSITIVE RESULTS MAY OCCUR DUE TO STRESS, DEPRESSION, ALCOHOLISM.