PT18Q - "Quest AD-Detect Phosphorylated tau181, Plasma"

New Test

Effective Date

07/28/2026

Included in Report

WML Test Directory Update | July 2026

Updated Test

QUEST AD-DETECT PHOSPHORYLATED TAU181, PLASMA

Test Details

Mnemonic

PT18Q

Ordering Code

3401179

CPT-4 Codes(s)

84393

Turnaround Time

3 - 5 days

Performed

Monday - Saturday

Legacy Code

PT18Q

Example Report

Download

Specimen Information

Collect

Lavender EDTA

Specimen Preparation

Centrifuge, separate plasma from cells and send 1.0 mL plasma in a screw capped plastic vial.

Minimum Volume

0.5 mL

Transport Temperature

Refrigerated

Rejection Criteria

Hemolysis

Stability

Room temperature: 14 days
Refrigerated: 22 days
Frozen: 22 days

Methodology

Electrochemiluminescence (ECLIA)

Reference Range

≤0.72 pg/mL

Performing Laboratory

Quest

New York DOH Approval Status

Yes

Test Name	Ordering Code	Result Code	Component Name	LOINC Code	AOE Prompt	Units
Quest AD-Detect Phosphorylated tau181, Plasma	3401179
		3401179	Quest AD-Detect Phosphorylated tau181, Plasma	103675-5	No

The CPT codes provided are for general informational purposes only and are based on an interpretation of AMA guidance. It is the sole responsibility of the billing party to determine CPT codes. Any questions regarding coding should be directed to the paying party.

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PT18Q – “Quest AD-Detect Phosphorylated tau181, Plasma”