With clinical terms we almost always have two ways of reporting. Using the first, we can report an observation by reporting a number of atomic variables which together fully describe the observation. For example, we have the following atomic observations for circumference measures. These variables let us deal with all of the unique kinds of circumferences for which we have not yet defined a pre-coordinated term. The following table shows examples of pre-coordinated names.
Table 21: Examples of Pre-Coordinated Names
| Code | Description |
|---|---|
| Circumference:Len:Pt:XXX:Qn | The actual measure of some circumference |
| Circumference site:Anat:Pt:*:Nom | Identifies the body part measured (specifies the System) |
| Circumference method:Type:Pt:XXX:Nom:* | Identifies the measuring technique used to obtain the circumference (answers = tape measure, derived, imaging) |
We also provide pre-coordinated terms that combine some of the atomic variables into one LOINC code. For example, we have:
8279-2 Circumference.at nipple line:Len:Pt:Chest:Qn
and
8293-3 Circumference^inspiration:Len:Pt:Chest:Qn
which provide more specificity and permit the key components of the measure to be expressed as one variable as is the convention in many clinical systems. We call these pre-coordinated codes “molecular” variables.
Within the LOINC database molecular variables will vary with respect to how many atomic components are aggregated. As is true in some laboratory areas, methods often are not included as part of a name, nor are they always reported. The most common molecular aggregation is between functional measure and a particular site of measurement (e.g., the many different intravascular sites for blood pressure measurements). But in some cases, the molecular variables represent combinations of specific measures and particular methods (e.g., the cardiac output measures). Please note that most molecular variables could also be accompanied by one or more atomic measures to provide special information about the measure, e.g., special circumstances of the measure, or the vendor model number or institutional inventory number of the measuring instrument.
When we have a variable that really reports what would have been contained in the name in a fully pre-coordinated term, we will place an asterisk in the part that will be reported as a value. For example, a variable that is used to report the anatomic site as an atomic variable, would have an asterisk (*) in the System part of the name. The variable used to report the method of a particular measure would have an asterisk (*) in the Method part of the name.