|
KMID : 1101220030350010029
|
|
2003 Volume.35 No. 1 p.29 ~ p.33
|
|
|
A Study of Lower Limit of Detection(LLD) in Clinical Chemistry Laboratories
|
|
Chang Sang-Wu
Kim Nam-Yong
Kwon Sun-Deuk
Lee Hee-Kyung
|
|
|
Abstract
|
|
|
|
Limit of detection is the single result which, with a stated probability, can be distnguished from a suitable blank. Limit of detection is the lowest amount of analyte in a sample that can be detected, but not be quantified as an exact value. This value is also referred to as the Minimum Detactable Activity(MDA, LLD). Once this value is determined, the linear range of an assay extends from the value for the MDA(LLD) to the value for the highest calibrator concentration. The concentration up to which the method has been shown previously to maintain acceptable linearity. The analytical sensitivity is simply stated as, the positivity of disease; the probability that the test is positive when the disease is present. The analytical sensitivity is determined as the concentration equivalent to the mean counts obtained from the zero sample plus 2 SD for immunometric and chemical assays or the mean minus 2 SD for competitive assays. Analytical sensitivity is also referred to as the Lower Limit of Detection(LLD, MDA). The formal definition of analytical sensitivity is, "the lowest concentration that can be distinguished from background noise." This concentration is properly termed the assay's detection limit, but it is most commonly referred to as sensitivity. Typically, this value is established by assaying replicates of a sample that is known to have no analyte present. Analytical specificity refers to the freedom of the method from interference from commonly occurring[e.g. lipids(lipemia), hemoglobin(hemolysis), bilirubin(icterus)] and commonly occurring [e.g. lipids (lipemia), hemoglobin (hemolysis), bilirubin (icterus)] and uncommonly occurring substances. The results of MDA that were studied on 18 tests in clinical chemistry are as follows: ALT, Albumin, ALP, IP, Amylase, Glucose, Cholesterol, Uric Acid, UN, Creatinine, and CK. Total Proteins were 0, AST (11.0 U/L), Total Bilirubin (0.7 mg/dL), GGT(2.3 mg/dL), LD(2.3 U/L), Triglyceride(1.0 mg/dL), and Calcium(0.2 mg/dL).
|
|
|
KEYWORD
|
|
|
Minmum detectable activity (MDA), Lower limit of detection (LLD), Analytical sensitivity, Analytical specificity
|
|
|
FullTexts / Linksout information
|
|
|
|
|
|
Listed journal information
|
|
|
|
|