Is K59.1 a billable ICD-10-CM code?

Yes. K59.1 is a billable, specific ICD-10-CM code and is valid for submission on a claim.

Where does K59.1 sit in the tabular list?

Diseases of the digestive system (K00-K95), in the block Other diseases of intestines (K55-K64).

What cannot be coded together with K59.1?

K59.1 carries an Excludes1 note, which means the conditions it lists can never be coded together with it on the same encounter.

K59.1

K59.1 — Functional diarrhea

Billable / specific codeICD-10-CM

K59.1 is a billable, specific ICD-10-CM code for functional diarrhea. It is valid for submission on a claim.

Excludes1 — never code together

These conditions cannot occur together. Billing both on the same encounter is a denial.

diarrhea NOS (R19.7)
irritable bowel syndrome with diarrhea (K58.0)

Other codes that can never be billed with K59.1

These codes carry an Excludes1 note pointing at K59.1. The conflict binds both ways, but ICD-10-CM only writes it down on one side — so you would not find this by reading K59.1 alone.

R19.4Change in bowel habit
R19.7Diarrhea, unspecified
K52.9Noninfective gastroenteritis and colitis, unspecified

Risk adjustment

K59.1 does not map to an HCC and does not risk-adjust under CMS-HCC V28. That is normal — most ICD-10 codes do not. It still needs to be coded correctly; it just will not move a RAF score.

Medicare coverage

K59.1 is named in 7 Medicare coverage policies — 7 listing it as supporting medical necessity. Which of them applies to you depends on your Medicare contractor, and coverage genuinely differs by state.

A55937Billing and Coding: Diagnostic Colonoscopy
A56394Billing and Coding: Colonoscopy and Sigmoidoscopy-Diagnostic
A56421Billing and Coding: CT of the Abdomen and Pelvis
A56456Billing and Coding: Colonoscopy/Sigmoidoscopy/Proctosigmoidoscopy

How K59.1 is indexed

Coders do not find codes by browsing the tabular list — they look them up in the alphabetic index, under the word the physician wrote. These are the index entries that lead here, so you can see which chart wordings map to K59.1.

Diarrhea, diarrheal›functional
Diarrhea, diarrheal›neurogenic

Related codes at this level

Codes that share K59. If K59.1 is not quite right, the correct code is usually one of these.

Questions about K59.1

Is K59.1 a billable ICD-10-CM code?: Yes. K59.1 is a billable, specific ICD-10-CM code and is valid for submission on a claim.
Where does K59.1 sit in the tabular list?: Diseases of the digestive system (K00-K95), in the block Other diseases of intestines (K55-K64).
What cannot be coded together with K59.1?: K59.1 carries an Excludes1 note, which means the conditions it lists can never be coded together with it on the same encounter.