R63.6 – Underweight

ICD-10-CM 2027 diagnosis code · General symptoms and signs

Billable code

ICD-10-CM code R63.6

Code: R63.6 (claims format: R636)
Description: Underweight
Billable: Yes – valid for HIPAA-covered transactions
Valid for: Dates of service October 1, 2026 – September 30, 2027 (FY2027)
Chapter: 18. Symptoms, signs and abnormal clinical and laboratory findings, not elsewhere classified (R00-R99)
Block: R50-R69 General symptoms and signs
Parent codes: R63

Notes for R63.6

Excludes1 (not coded here):

abnormal weight loss (R63.4)
anorexia nervosa (F50.0-)
malnutrition (E40-E46)

Use additional code:

code to identify body mass index (BMI), if known (Z68.-)

Notes inherited from parent codes

Instructional notes at a category or block level apply to every code below it.

R63 – Symptoms and signs concerning food and fluid intake

Excludes1 (not coded here):

bulimia NOS (F50.2-)

Index terms for R63.6

Entries in the ICD-10-CM alphabetic index that lead to this code:

Underweight

Related codes in R63

R63.0 – AnorexiaBillable
R63.1 – PolydipsiaBillable
R63.2 – PolyphagiaBillable
R63.3 – Feeding difficultiesHeader
R63.4 – Abnormal weight lossBillable
R63.5 – Abnormal weight gainBillable
R63.8 – Other symptoms and signs concerning food and fluid intakeBillable

Frequently asked questions

What is ICD-10 code R63.6?

R63.6 is the ICD-10-CM code for underweight, in the block R50-R69 (General symptoms and signs).

Is R63.6 a billable code?

Yes. R63.6 is a billable/specific code that can be used to indicate a diagnosis for reimbursement purposes.

What category does R63.6 belong to?

It belongs to category R63 – Symptoms and signs concerning food and fluid intake.

Source: CDC/NCHS ICD-10-CM FY2027 code files, tabular list and index. Reference only – code assignment must follow the official ICD-10-CM guidelines and documentation in the medical record.