2021 ICD-10-CM Diagnosis Code R63.6

Underweight

    2016 2017 2018 2019 2020 2021 Billable/Specific Code
  • R63.6 is a billable/specific ICD-10-CM code that can be used to indicate a diagnosis for reimbursement purposes.
  • The 2021 edition of ICD-10-CM R63.6 became effective on October 1, 2020.
  • This is the American ICD-10-CM version of R63.6 - other international versions of ICD-10 R63.6 may differ.
Use Additional
Use Additional Help
Certain conditions have both an underlying etiology and multiple body system manifestations due to the underlying etiology. For such conditions the ICD-10-CM has a coding convention that requires the underlying condition be sequenced first followed by the manifestation. Wherever such a combination exists there is a "use additional code" note at the etiology code, and a "code first" note at the manifestation code. These instructional notes indicate the proper sequencing order of the codes, etiology followed by manifestation. In most cases the manifestation codes will have in the code title, "in diseases classified elsewhere." Codes with this title are a component of the etiology/manifestation convention. The code title indicates that it is a manifestation code. "In diseases classified elsewhere" codes are never permitted to be used as first listed or principle diagnosis codes. They must be used in conjunction with an underlying condition code and they must be listed following the underlying condition.
  • code to identify body mass index (BMI), if known (
    ICD-10-CM Diagnosis Code Z68
    • Z68 Body mass index [BMI]
      • Z68.1 Body mass index [BMI] 19.9 or less, adult
      • Z68.2 Body mass index [BMI] 20-29, adult
        • Z68.20 Body mass index [BMI] 20.0-20.9, adult
        • Z68.21 Body mass index [BMI] 21.0-21.9, adult
        • Z68.22 Body mass index [BMI] 22.0-22.9, adult
        • Z68.23 Body mass index [BMI] 23.0-23.9, adult
        • Z68.24 Body mass index [BMI] 24.0-24.9, adult
        • Z68.25 Body mass index [BMI] 25.0-25.9, adult
        • Z68.26 Body mass index [BMI] 26.0-26.9, adult
        • Z68.27 Body mass index [BMI] 27.0-27.9, adult
        • Z68.28 Body mass index [BMI] 28.0-28.9, adult
        • Z68.29 Body mass index [BMI] 29.0-29.9, adult
      • Z68.3 Body mass index [BMI] 30-39, adult
        • Z68.30 Body mass index [BMI]30.0-30.9, adult
        • Z68.31 Body mass index [BMI] 31.0-31.9, adult
        • Z68.32 Body mass index [BMI] 32.0-32.9, adult
        • Z68.33 Body mass index [BMI] 33.0-33.9, adult
        • Z68.34 Body mass index [BMI] 34.0-34.9, adult
        • Z68.35 Body mass index [BMI] 35.0-35.9, adult
        • Z68.36 Body mass index [BMI] 36.0-36.9, adult
        • Z68.37 Body mass index [BMI] 37.0-37.9, adult
        • Z68.38 Body mass index [BMI] 38.0-38.9, adult
        • Z68.39 Body mass index [BMI] 39.0-39.9, adult
      • Z68.4 Body mass index [BMI] 40 or greater, adult
        • Z68.41 Body mass index [BMI]40.0-44.9, adult
        • Z68.42 Body mass index [BMI] 45.0-49.9, adult
        • Z68.43 Body mass index [BMI] 50.0-59.9, adult
        • Z68.44 Body mass index [BMI] 60.0-69.9, adult
        • Z68.45 Body mass index [BMI] 70 or greater, adult
      • Z68.5 Body mass index [BMI] pediatric
        • Z68.51 Body mass index [BMI] pediatric, less than 5t...
        • Z68.52 Body mass index [BMI] pediatric, 5th percenti...
        • Z68.53 Body mass index [BMI] pediatric, 85th percent...
        • Z68.54 Body mass index [BMI] pediatric, greater than...
    Z68.-
    )
Type 1 Excludes
Type 1 Excludes Help
A type 1 excludes note is a pure excludes. It means "not coded here". A type 1 excludes note indicates that the code excluded should never be used at the same time as R63.6. A type 1 excludes note is for used for when two conditions cannot occur together, such as a congenital form versus an acquired form of the same condition.
  • abnormal weight loss (
    ICD-10-CM Diagnosis Code R63.4

    Abnormal weight loss

      2016 2017 2018 2019 2020 2021 Billable/Specific Code
    R63.4
    )
  • anorexia nervosa (
    ICD-10-CM Diagnosis Code F50.0

    Anorexia nervosa

      2016 2017 2018 2019 2020 2021 Non-Billable/Non-Specific Code
    Type 1 Excludes
    • loss of appetite (R63.0)
    • psychogenic loss of appetite (F50.89)
    F50.0-
    )
  • malnutrition (E40-E46
    ICD-10-CM Range E40-E46

    Malnutrition

    Type 1 Excludes
    • intestinal malabsorption (K90.-)
    • sequelae of protein-calorie malnutrition (E64.0)
    Type 2 Excludes
    • E40 Kwashiorkor
    • E41 Nutritional marasmus
    • E42 Marasmic kwashiorkor
    • E43 Unspecified severe protein-calorie malnu...
    • E44 Protein-calorie malnutrition of moderate...
    • E45 Retarded development following protein-c...
    • E46 Unspecified protein-calorie malnutrition
    )
The following code(s) above R63.6 contain annotation back-references
Annotation Back-References
In this context, annotation back-references refer to codes that contain:
  • Applicable To annotations, or
  • Code Also annotations, or
  • Code First annotations, or
  • Excludes1 annotations, or
  • Excludes2 annotations, or
  • Includes annotations, or
  • Note annotations, or
  • Use Additional annotations
that may be applicable to R63.6:
  • R00-R99
    2021 ICD-10-CM Range R00-R99

    Symptoms, signs and abnormal clinical and laboratory findings, not elsewhere classified

    Note
    • This chapter includes symptoms, signs, abnormal results of clinical or other investigative procedures, and ill-defined conditions regarding which no diagnosis classifiable elsewhere is recorded.
    • Signs and symptoms that point rather definitely to a given diagnosis have been assigned to a category in other chapters of the classification. In general, categories in this chapter include the less well-defined conditions and symptoms that, without the necessary study of the case to establish a final diagnosis, point perhaps equally to two or more diseases or to two or more systems of the body. Practically all categories in the chapter could be designated 'not otherwise specified', 'unknown etiology' or 'transient'. The Alphabetical Index should be consulted to determine which symptoms and signs are to be allocated here and which to other chapters. The residual subcategories, numbered .8, are generally provided for other relevant symptoms that cannot be allocated elsewhere in the classification.
    • The conditions and signs or symptoms included in categories R00-R94 consist of:
    • (a) cases for which no more specific diagnosis can be made even after all the facts bearing on the case have been investigated;
    • (b) signs or symptoms existing at the time of initial encounter that proved to be transient and whose causes could not be determined;
    • (c) provisional diagnosis in a patient who failed to return for further investigation or care;
    • (d) cases referred elsewhere for investigation or treatment before the diagnosis was made;
    • (e) cases in which a more precise diagnosis was not available for any other reason;
    • (f) certain symptoms, for which supplementary information is provided, that represent important problems in medical care in their own right.
    Type 2 Excludes
    • abnormal findings on antenatal screening of mother (O28.-)
    • certain conditions originating in the perinatal period (P04-P96)
    • signs and symptoms classified in the body system chapters
    • signs and symptoms of breast (N63, N64.5)
    Symptoms, signs and abnormal clinical and laboratory findings, not elsewhere classified
  • R63
    ICD-10-CM Diagnosis Code R63

    Symptoms and signs concerning food and fluid intake

      2016 2017 2018 2019 2020 2021 Non-Billable/Non-Specific Code
    Type 1 Excludes
    Symptoms and signs concerning food and fluid intake
Approximate Synonyms
  • Underweight in childhood with bmi between 0 to 4 percentile
  • Underweight, pediatrics (0-4 bmi percentile)
ICD-10-CM R63.6 is grouped within Diagnostic Related Group(s) (MS-DRG v38.0):
  • 640 Miscellaneous disorders of nutrition, metabolism, fluids and electrolytes with mcc
  • 641 Miscellaneous disorders of nutrition, metabolism, fluids and electrolytes without mcc

Convert R63.6 to ICD-9-CM

Code History
  • 2016 (effective 10/1/2015): New code (first year of non-draft ICD-10-CM)
  • 2017 (effective 10/1/2016): No change
  • 2018 (effective 10/1/2017): No change
  • 2019 (effective 10/1/2018): No change
  • 2020 (effective 10/1/2019): No change
  • 2021 (effective 10/1/2020): No change

Diagnosis Index entries containing back-references to R63.6:

ICD-10-CM Codes Adjacent To R63.6
R62.52 Short stature (child)
R62.59 Other lack of expected normal physiological development in childhood
R62.7 Adult failure to thrive
R63 Symptoms and signs concerning food and fluid intake
R63.0 Anorexia
R63.1 Polydipsia
R63.2 Polyphagia
R63.3 Feeding difficulties
R63.4 Abnormal weight loss
R63.5 Abnormal weight gain
R63.6 Underweight
R63.8 Other symptoms and signs concerning food and fluid intake
R64 Cachexia
R65 Symptoms and signs specifically associated with systemic inflammation and infection
R65.1 Systemic inflammatory response syndrome (SIRS) of non-infectious origin
R65.10 …… without acute organ dysfunction
R65.11 …… with acute organ dysfunction
R65.2 Severe sepsis
R65.20 …… without septic shock
R65.21 …… with septic shock
R68 Other general symptoms and signs

Reimbursement claims with a date of service on or after October 1, 2015 require the use of ICD-10-CM codes.