R63.6 - Underweight

Version 2023
No Valid Principal Dx
ICD-10:R63.6
Short Description:Underweight
Long Description:Underweight
Status: Valid for Submission
Version:ICD-10-CM 2023
Code Classification:
  • Symptoms, signs and abnormal clinical and laboratory findings, not elsewhere classified (R00–R99)
    • General symptoms and signs (R50-R69)
      • Symptoms and signs concerning food and fluid intake (R63)

R63.6 is a billable ICD-10 code used to specify a medical diagnosis of underweight. The code is valid during the fiscal year 2023 from October 01, 2022 through September 30, 2023 for the submission of HIPAA-covered transactions.

According to ICD-10-CM guidelines this code should not to be used as a principal diagnosis code when a related definitive diagnosis has been established.

Approximate Synonyms

The following clinical terms are approximate synonyms or lay terms that might be used to identify the correct diagnosis code:

Tabular List of Diseases and Injuries

The Tabular List of Diseases and Injuries is a list of ICD-10 codes, organized "head to toe" into chapters and sections with coding notes and guidance for inclusions, exclusions, descriptions and more. The following references are applicable to this diagnosis code:


Use Additional Code

Use Additional Code
The “use additional code” indicates that a secondary code could be used to further specify the patient’s condition. This note is not mandatory and is only used if enough information is available to assign an additional code.

Type 1 Excludes

Type 1 Excludes
A type 1 excludes note is a pure excludes note. It means "NOT CODED HERE!" An Excludes1 note indicates that the code excluded should never be used at the same time as the code above the Excludes1 note. An Excludes1 is used when two conditions cannot occur together, such as a congenital form versus an acquired form of the same condition.

Index to Diseases and Injuries References

The Index to Diseases and Injuries is an alphabetical listing of medical terms, with each term mapped to one or more ICD-10 code(s). The following references for this diagnosis code are found in the injuries and diseases index:

Convert to ICD-9 Code

Source ICD-10 CodeTarget ICD-9 Code
R63.6783.22 - Underweight

Patient Education


Body Weight

Do you know if your current weight is healthy? "Underweight", "normal", "overweight", and "obese" are all labels for ranges of weight. Obese and overweight mean that your weight is greater than it should be for your health. Underweight means that it is lower than it should be for your health. Your healthy body weight depends on your sex and height. For children, it also depends on your age.

A sudden, unexpected change in weight can be a sign of a medical problem. Causes for sudden weight loss can include:

Sudden weight gain can be due to medicines, thyroid problems, heart failure, and kidney disease.

Good nutrition and exercise can help in losing weight. Eating extra calories within a well-balanced diet and treating any underlying medical problems can help to add weight.


[Learn More in MedlinePlus]

Code History