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|Performed by||China Basin Chemistry|
|In House Availability||Wednesday (day shift)|
|Method||Chemiluminescentimmunometric (Siemens Immulite 2000)|
|Collection Instructions||Draw specimen between 0700 and 1000 hours if possible. If drawn at other times reference ranges do not apply.
Sample must be collected in pre-chilled vacutainer and delivered immediately to laboratory on ice.
|Container type||Lavender top (on ice)|
|Amount to Collect||3 mL blood|
|Sample type||EDTA plasma|
|Preferred volume||1.5 mL plasma|
|Min. Volume||0.5 mL plasma|
|UCSF Rejection Criteria||Not delivered on ice|
|Processing notes||Process immediately. Avoid all contact with glass during processing and separation. Separate and freeze plasma in plastic tube at -20C.|
Reference ranges adopted from Quest Diagnostics as determined in adult and pediatric groups using the same methodology (Siemens Immulite 2000 chemiluminescent assay). The Quest adult reference range was verified by in house testing of 10 male and 23 female lab volunteers. Owing to circadian variation in ACTH levels, the reference ranges are only applicable to samples collected between 0700 and 1000 hours.
|Stability||Room temp or refrigerated 4 hours, frozen at -20C 1 year.|
|Turn around times||1-8 days.|
|Additional information||The ACTH precursor POMC has 2% cross reactivity in this Immulite immunochemiluminometric assay (based on in house studies using purified POMC).
This level of cross reactivity can be clinically significant because patients with non-carcinoid ectopic ACTH syndromes can have very high circulating concentrations of POMC-like ACTH precursors (139 – 18,000 pmol/L) - high enough to elevate ACTH in this assay by anywhere between 3 – 360 pmol/L (~13 - 1636 ng/L).
Patients with macroadenomas have been reported to have circulating concentrations of ACTH precursors that would be high enough to elevate ACTH in our assay by anywhere between 2 – 75 pmol/L (12 - 340 ng/L)
Ref: Oliver, Davis, and White, Pituitary 6:119-126, 2009 and Gibson et al, JCEM 81:496-502, 1996)
|Last Updated||4/17/2013 2:04:51 PM|