HL7 DLT Delta
HL7 datatype components DLT components from HL7 v2.5.1 Hide components
These are the generated components for the version selected at the top of the page. The article stays practical, and this panel follows the chosen HL7 version.
Components
DLT describes a delta value, usually around reference ranges or observation master data. The trap is to send a number without saying whether it is an absolute change, a percentage, or a local interpretation.
In this guide, DLT appears in OM2.9. That used-by list is a good reality check: the datatype is only half the story, and the field that uses it tells you the workflow.
The component panel above is expanded by default because most datatype pages are used as quick lookup pages. Start there for the exact HL7 v2.5.1 shape, then use the notes below for the practical gotchas.
DLT-1 to DLT-4: Component Quick Read
The generated component panel above is the formal quick lookup. The short version is below so you can scan the shape without counting carets by eye.
The table-backed components here are DLT-3. Keep those values to the table or value set your implementation guide names, especially when the field is crossing organization boundaries.
- DLT-1 Normal Range - Normal Range. Type NR.
- DLT-2 Numeric Threshold - Numeric Threshold. Type NM.
- DLT-3 Change Computation - Change Computation. Type ID. Table 0523.
- DLT-4 Days Retained - Days Retained. Type NM.
Practical Notes
Keep numeric values numeric. Do not mix display formatting, unit text, or currency labels into the number component when the datatype has a separate place for that meaning. A format validator for whole numbers or decimals is a simple way to catch this before the receiving system has to complain.
In HL7 Soup Web, click a field that uses DLT and the interpretation view will show which component you are sitting in and where that value lives in the raw message. That is especially handy with compact datatypes because one missing caret can move every value after it.
Official and Reference Notes
For formal reference, compare the generated HL7 v2.5.1 panel above with the HL7 v2.5.1 datatype list and the HL7 Terminology data type code system. Local implementation guides can narrow allowed values, tables, and component usage.