ReferenceRange

Reference range for clinical observations and laboratory results. Defines normal, therapeutic, or critical value boundaries with support for population-specific ranges by age and demographics. Follows FHIR Observation.referenceRange conventions.

Overview

ReferenceRange specifies acceptable value boundaries for clinical measurements. Ranges can be fully bounded (both low and high), semi-bounded (only low or only high), or open. Different range types serve different purposes: normal ranges define healthy values, therapeutic ranges define treatment targets, and critical ranges define dangerous thresholds. Population-specific customization allows age and demographic-appropriate interpretation.

Key Concepts

Range Structure

Each range can have:

Field	Purpose	Example
`low`	Lower bound with value and unit	70 mg/dL
`high`	Upper bound with value and unit	100 mg/dL
`type`	Clinical purpose of the range	normal, therapeutic, critical
`text`	Human-readable description	"Normal fasting glucose"
`appliesTo`	Population characteristics	["adult", "female"]
`age`	Age range in years	{ low: 18, high: 65 }

Range Types

Type	Purpose	Example
`normal`	Healthy/expected values	Fasting glucose 70-100 mg/dL
`recommended`	Target values for health	LDL cholesterol < 100 mg/dL
`treatment`	Goals during treatment	A1C < 7% for diabetics
`therapeutic`	Drug level targets	Warfarin INR 2.0-3.0
`critical`	Dangerous thresholds	Potassium < 2.5 mEq/L

Bounded vs Semi-Bounded

Fully Bounded - Both limits defined:

Glucose: 70-100 mg/dL
Heart rate: 60-100 bpm

Lower Bound Only - Minimum threshold:

Hemoglobin: > 12 g/dL (anemia threshold)
Potassium: > 2.5 mEq/L (critical low)

Upper Bound Only - Maximum threshold:

Bilirubin: < 1.2 mg/dL
TSH: < 4.0 mIU/L

Units of Measure

Values include UCUM-compatible units:

value - Numeric measurement
unit - Human-readable unit (e.g., "mg/dL")
system - Unit system URI (http://unitsofmeasure.org)
code - UCUM code for interoperability

Population-Specific Ranges

Different populations have different normal values:

By Sex

Hemoglobin: Male 14-18 g/dL, Female 12-16 g/dL

By Age

Heart rate: Infant 100-160 bpm, Adult 60-100 bpm

By Condition

A1C: Non-diabetic < 5.7%, Diabetic target < 7%

Use Cases

Laboratory Result Interpretation

When displaying lab results:

Retrieve applicable reference ranges
Match patient demographics (age, sex)
Compare result to range boundaries
Flag values outside normal range
Highlight critical values

Clinical Decision Support

For automated alerting:

Define critical ranges for dangerous values
Trigger alerts when results exceed critical thresholds
Notify appropriate care team
Document alert and response

Drug Level Monitoring

For therapeutic drug monitoring:

Define therapeutic ranges for medications
Monitor trough/peak levels
Alert if outside therapeutic window
Guide dose adjustments

Quality Metrics

For clinical quality measures:

Define recommended ranges for outcomes
Track patient values vs targets
Report percentage within range
Identify improvement opportunities

Result Reporting

For patient-facing results:

Show result with reference range
Indicate normal/abnormal status
Provide age/sex-appropriate comparison
Include interpretive text

Related Entities

Entity	Relationship	Description
LaboratoryResult	Used by	Lab results compared against reference ranges
VitalSign	Used by	Vital signs with normal ranges

Calculated Fields

Field	Type	Description
`hasLow`	boolean	True if lower bound is defined
`hasHigh`	boolean	True if upper bound is defined
`isBounded`	boolean	True if both lower and upper bounds are defined

Enums

type

Value	Description
`normal`	Normal/healthy reference range for general population
`recommended`	Recommended target values for optimal health
`treatment`	Target range during active treatment
`therapeutic`	Therapeutic drug level range for medication monitoring
`critical`	Critical thresholds indicating immediate clinical concern

9 properties

Schema

Properties

Property	Type	Mode	Description	Required
low	object	stored	Lower bound of the reference range, representing the minimum acceptable or normal value for the measurement Example: `{"value":70,"unit":"mg/dL","system":"http://unitsofmeasure.org","code":"mg/dL"}`	Optional
high	object	stored	Upper bound of the reference range, representing the maximum acceptable or normal value for the measurement Example: `{"value":100,"unit":"mg/dL","system":"http://unitsofmeasure.org","code":"mg/dL"}`	Optional
type	string	enum	Classification of the reference range indicating its clinical or contextual meaning Values: `normal, recommended, treatment, therapeutic, critical` Example: `"normal"`	Optional
text	string	stored	Human-readable textual description or narrative of the reference range, useful for conveying context, conditions, or qualitative aspects not captured by numeric bounds Example: `"Normal fasting blood glucose for non-diabetic adults"`	Optional
appliesTo	array	stored	Population characteristics or demographic groups to which this reference range applies, enabling population-specific interpretations (e.g., gender, age category, pregnancy status, ethnicity) Example: `["adult","female"]`	Optional
age	object	stored	Age range in years for which this reference range is valid, enabling age-specific clinical interpretations Example: `{"low":18,"high":65}`	Optional
hasLow	boolean	computed	Calculated indicator of whether a lower bound is defined for this reference range Example: `true`	Optional
hasHigh	boolean	computed	Calculated indicator of whether an upper bound is defined for this reference range Example: `true`	Optional
isBounded	boolean	computed	Calculated indicator of whether both lower and upper bounds are defined, signifying a fully bounded reference range Example: `true`	Optional

Examples

Example 1

{
  "@type": "ReferenceRange",
  "low": {
    "value": 70,
    "unit": "mg/dL",
    "system": "http://unitsofmeasure.org",
    "code": "mg/dL"
  },
  "high": {
    "value": 100,
    "unit": "mg/dL",
    "system": "http://unitsofmeasure.org",
    "code": "mg/dL"
  },
  "type": "normal",
  "text": "Normal fasting blood glucose for non-diabetic adults",
  "appliesTo": [
    "adult"
  ],
  "age": {
    "low": 18,
    "high": 120
  }
}

Example 2

{
  "@type": "ReferenceRange",
  "low": {
    "value": 12,
    "unit": "g/dL",
    "system": "http://unitsofmeasure.org",
    "code": "g/dL"
  },
  "high": {
    "value": 15.5,
    "unit": "g/dL",
    "system": "http://unitsofmeasure.org",
    "code": "g/dL"
  },
  "type": "normal",
  "text": "Normal hemoglobin levels for adult females",
  "appliesTo": [
    "adult",
    "female"
  ],
  "age": {
    "low": 18,
    "high": 120
  }
}

Example 3

{
  "@type": "ReferenceRange",
  "low": {
    "value": 2.5,
    "unit": "mEq/L",
    "system": "http://unitsofmeasure.org",
    "code": "meq/L"
  },
  "type": "critical",
  "text": "Critical low potassium - below this threshold requires immediate intervention",
  "appliesTo": [
    "adult"
  ]
}

Example 4

{
  "@type": "ReferenceRange",
  "high": {
    "value": 15,
    "unit": "mg/dL",
    "system": "http://unitsofmeasure.org",
    "code": "mg/dL"
  },
  "type": "critical",
  "text": "Critical high bilirubin for newborns - above this threshold may indicate severe jaundice",
  "appliesTo": [
    "newborn"
  ],
  "age": {
    "low": 0,
    "high": 0.08
  }
}

Example 5

{
  "@type": "ReferenceRange",
  "low": {
    "value": 2,
    "unit": "ratio",
    "system": "http://unitsofmeasure.org",
    "code": "{ratio}"
  },
  "high": {
    "value": 3,
    "unit": "ratio",
    "system": "http://unitsofmeasure.org",
    "code": "{ratio}"
  },
  "type": "therapeutic",
  "text": "Therapeutic INR range for patients on warfarin anticoagulation therapy",
  "appliesTo": [
    "adult"
  ]
}

Example 6

{
  "@type": "ReferenceRange",
  "low": {
    "value": 60,
    "unit": "bpm",
    "system": "http://unitsofmeasure.org",
    "code": "/min"
  },
  "high": {
    "value": 100,
    "unit": "bpm",
    "system": "http://unitsofmeasure.org",
    "code": "/min"
  },
  "type": "normal",
  "text": "Normal resting heart rate for pediatric patients aged 6-15 years",
  "appliesTo": [
    "pediatric"
  ],
  "age": {
    "low": 6,
    "high": 15
  }
}