Editing Reference range (section)

==One-sided cut-off values==
In many cases, only one side of the range is usually of interest, such as with markers of pathology including [[CA19-9|cancer antigen 19-9]], where it is generally without any clinical significance to have a value below what is usual in the population. Therefore, such targets are often given with only one limit of the reference range given, and, strictly, such values are rather ''cut-off values'' or ''threshold values''.

They may represent both standard ranges and optimal health ranges. Also, they may represent an appropriate value to distinguish healthy person from a specific disease, although this gives additional variability by different diseases being distinguished. For example, for [[NT-proBNP]], a lower cut-off value is used in distinguishing healthy babies from those with [[acyanotic heart disease]], compared to the cut-off value used in distinguishing healthy babies from those with [[congenital nonspherocytic anemia]].<ref name=Moses2011>[http://www.medscape.com/viewarticle/735842_3 Screening for Congenital Heart Disease with NT-proBNP: Results] By Emmanuel Jairaj Moses, Sharifah A.I. Mokhtar, Amir Hamzah, Basir Selvam Abdullah, and Narazah Mohd Yusoff. Laboratory Medicine. 2011;42(2):75–80.  American Society for Clinical Pathology</ref>