Quantity

This element is meant to denote quantities of items such as medications. The unit of a dose can be expressed with NCIT terms such as Milligram, Microgram, or Unit. The value should be expressed as a number.

Data model

Definition of the Quantity element
Field Type Multiplicity Description
unit OntologyClass 1..1 The kind of unit. REQUIRED.
value double 1..1 the value of the quantity in the units e.g. 2.0 mg. REQUIRED.
reference_range ReferenceRange 0..1 the normal range for the value

Examples

The following message could be used to represent the quantity corresponding to a 15 mg tablet of Meloxicam.

unit:
  id: "NCIT:C28253"
  label: "Milligram"
value: 15.0

The following message could be used to represent the quantity corresponding to a bolus of 5000 units of Heparin.

unit:
  id: "NCIT:C44278"
  label: "Unit"
value: 5000

The following example shows a quantity for a platelet count per microliter, with a reference range.

unit:
  id: "UO:0000316"
  label: "cells per microliter"
value: 300000.0
referenceRange:
  unit:
    id: "UO:0000316"
    label: "cells per microliter"
  low: 150000.0
  high: 450000.0

Explanations

unit

Ontology terms for units can be taken from the National Cancer Institute Thesaurus (NCIT), from the subhierarchy for Unit of Measure (Code C25709).

value

The corresponding value of the quantity in the indicated units.