Category · F70-F79 block
F72 — Severe mental retardation
Terminology note: ICD-10's own term for this block is "mental retardation." Modern clinical and educational usage prefers "intellectual disability" (used in DSM-5 and in ordinary clinical practice since the mid-2010s), and ICD-11 has renamed and relocated this entire classification territory to "disorders of intellectual development." This page keeps ICD-10's actual code and official title for classification accuracy, and uses person-first language throughout ("a person with an intellectual disability"), never a label standing in for the person.
What is this category?
F72 continues the same dual-criteria scale one grade further, at an approximate IQ range where support needs are typically extensive and lifelong, and where associated physical or sensory impairments are more commonly present alongside the intellectual disability itself.
Core diagnostic concept
F72 requires the same dual criteria as F70/F71 — significantly subnormal intellectual functioning and a matching adaptive-functioning deficit, with developmental onset — at an approximate IQ range of 20-34. Support needs are typically extensive across essentially all areas of daily living, and associated motor, sensory, or other physical impairments are more commonly present than at higher grades, though the grade itself is still defined by the same intellectual/adaptive dual criteria, not by the presence of a physical impairment.
Key diagnostic features
- Approximate IQ range 20-34
- A lower approximate range than F71, on the same testing basis.
- Extensive, typically lifelong support needs
- Support needs typically span essentially all areas of daily living.
- Associated impairments more common
- Motor, sensory, or other physical impairments are more commonly present alongside the intellectual disability at this grade, though not required for the classification itself.
- Onset during the developmental period
- Present from early childhood, as with every grade in this block.
How to weigh evidence
These learning labels are teaching aids, not official ICD-10 terminology (see Sources and Method).
- supports Testing in the approximate severe range together with extensive support needs across essentially all daily-living domains, present since early childhood.
- consistent not decisive The presence of an associated motor or sensory impairment alone, without independent evidence of the intellectual/adaptive picture.
- raises alternative A picture where grading is specifically complicated by a coexisting sensory or physical impairment that makes standard assessment difficult — this points toward F78 rather than a confident F72 grade.
- contradicts or weakens Insufficient information to confirm either criterion confidently.
- missing and necessary to ask Whether standard assessment was actually possible, or whether an associated impairment made grading specifically difficult.
Diagnostic boundary
F72 is distinguished from F71 and F73 by the same dual criteria at successive thresholds, and from F78 by whether grading was actually achievable or was specifically confounded by an associated sensory, physical, or behavioural impairment.
Full comparisons:
Duration and course
Minimum duration: Onset during the developmental period, as with every grade in this block.
Course: A stable, typically lifelong pattern of extensive support need.
Included presentations
- Testing in the approximate severe range together with extensive support needs across essentially all daily-living domains.
Exclusions and distinguishing presentations
| If this is true instead… | Consider | Why |
|---|---|---|
| Support needs and intellectual functioning more consistent with the moderate range | F71 | The dual criteria, applied at the moderate threshold, may instead support F71. |
| Grading specifically made difficult by an associated sensory, physical, or behavioural impairment | F78 | F78 is reserved for exactly this situation — a confounded assessment, not a confidently reached severe grade. |
Four-character subtypes (orientation)
As with every category in this block, the fourth character records behavioural impairment independently of the severity grade itself.
- F72.0 — No, or minimal, impairment of behaviour
- Behaviour does not require particular attention or treatment beyond the intellectual disability itself. (in_depth)
- F72.1 — Significant impairment of behaviour, requiring attention or treatment
- A behavioural disturbance (e.g. aggression, self-injury) significant enough to need its own dedicated attention, independent of the intellectual disability grade itself. (in_depth)
- F72.8 — Other impairments of behaviour
- A behavioural picture not fitting the other listed states. (taught for orientation only, not separately assessed in this pilot)
- F72.9 — Without mention of impairment of behaviour
- No information given about whether a behavioural impairment is present. (taught for orientation only, not separately assessed in this pilot)
External causes to check first
Categories in this block require that the disturbance is not better explained by another external cause listed below. These short capsules are reminders, not full teaching modules.
Boundary capsule — The dual criteria and grading logic across F70-F79
A shared reasoning check for every category in this block: none of F70-F73 can be supported by an IQ score alone, none of them can be supported by an adaptive-functioning impression alone, and the severity grade (F70-F73) is a separate question from both the behavioural-impairment fourth character and from whether enough information exists to grade at all (F78 versus F79).
What to check:
- Both criteria, together: is there evidence of both significantly subnormal general intellectual functioning (an approximate IQ range) AND a matching concurrent deficit in adaptive functioning (communication, self-care, home living, social and community skills)? Either one alone, without the other, does not support an F70-F73 classification.
- Onset: has the pattern been present since the developmental period (conventionally, before adulthood), rather than appearing as a decline from a previously typical baseline later in life? A later, datable decline points toward an acquired dementia (F00-F03), not toward this block, however similar the resulting scores look.
- Severity grade versus behavioural-impairment axis: is the question 'how subnormal is intellectual and adaptive functioning' (F70 mild, F71 moderate, F72 severe, F73 profound) being kept separate from the independent fourth-character question 'is there also a significant behavioural impairment requiring its own attention or treatment' (.0-.9)? A significant behavioural impairment does not, by itself, make the severity grade any more or less severe.
- F78 versus F79: when a case cannot be graded into F70-F73, is that because grading is specifically confounded by an identifiable associated sensory, physical, or behavioural impairment that makes standard assessment difficult (points toward F78), or because there is genuinely insufficient information available to grade at all, with no such confound identified (points toward F79)? These are two different reasons for not grading, not interchangeable labels for 'unclear.'
A full standardized cognitive and adaptive-functioning assessment by a qualified professional, which is outside this capsule's scope and is needed before any of these classifications is used in real clinical, educational, or support-planning practice.
Worked example — confirming a severe grade rather than defaulting to it
A 6-year-old requires extensive support across essentially all daily-living activities and has no associated sensory or physical impairment that would complicate assessment. A comprehensive developmental assessment, completed without difficulty, places her general intellectual functioning in the approximate severe range, consistent since infancy.
- Step 1 — Check the intellectual-functioning evidence: a comprehensive, unconfounded assessment places her in the approximate severe range (IQ 20-34).
- Step 2 — Check the adaptive-functioning picture: extensive support needs across essentially all domains.
- Step 3 — Check that assessment was actually achievable: no associated sensory or physical impairment complicated the assessment.
- Conclusion — With a confidently completed assessment supporting both criteria at this range, F72 is supported, rather than F78 (which would require the assessment itself to have been confounded).
Interactive practice
- Type A Markedly limited communication since infancy Recognition / application · Foundation
- Type B How much residual ability is “some”? Boundary discrimination · Transfer
Retrieval prompts
Try answering each of these from memory before revealing where to check. Nothing you think or type here is sent or saved anywhere.
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State the approximate IQ range associated with F72.
Reveal answer location
Check Duration and course, Diagnostic boundary, or the rapid revision card below — the cue you need is one of those, in this category's own already-authored wording.
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Explain what would make F78, rather than F72, the more accurate classification for an otherwise similar presentation.
Reveal answer location
Check Duration and course, Diagnostic boundary, or the rapid revision card below — the cue you need is one of those, in this category's own already-authored wording.
These self-checks are a personal study aid only, visible to you on this page for this visit — they are not stored and do not affect your mastery dimensions.
Rapid revision card
F72: The same dual criteria as F70/F71, at an approximate IQ range of 20-34, with typically extensive, lifelong support needs.
Decisive boundary cues:
- A confidently completed assessment at this range -> weighs toward F72.
- An assessment confounded by an associated sensory/physical impairment -> weighs toward F78 instead.
- Support needs and range consistent with the profound threshold -> weighs toward F73.
Duration/course: Onset during the developmental period, as a stable, typically lifelong pattern.
Nearest alternatives: F71, F73, F78
Common mistake: Assuming a severe grade whenever an associated physical or sensory impairment is present, rather than checking whether assessment was actually achievable.
Retrieval prompt: What would tell you that grading here was actually confounded, pointing toward F78 instead?
(or use your browser's print function) Open full-page printable revision view →
Related glossary terms
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Adaptive functioning
The practical skills a person uses to meet the everyday demands of independent living — communication, self-care, home living, social skills, use of community resources, self-direction, and similar domains — assessed relative to what is typically expected at a person's age and cultural context. A concurrent deficit in adaptive functioning, alongside subnormal intellectual functioning, is one of the two criteria required for an intellectual disability classification (F70-F73); intellectual functioning alone is never sufficient.
Source basis
WHO ICD-10 international classification structure and code/title (ICD-10 Browser, 2019 English release).
Original educational synthesis, informed by general published clinical-education understanding of ICD-10 F70-F79; no verbatim CDDG or DCR text is reproduced. See Sources and Method for the full policy.
Last reviewed: 2026-09-17. Full policy: Sources and Method.
Educational resource only. This page and its cases teach ICD-10 classification reasoning using fictional scenarios. It does not diagnose real people and should not be used to assess yourself or anyone else. Intellectual disability is not the person — every person with an intellectual disability deserves the same dignity and respect as anyone else. If you are concerned about a child's development, or about an adult's intellectual or adaptive functioning, please speak with a qualified professional for assessment and support.