ICD-10-CM tabular list

T51-T65 — Toxic effects of substances chiefly nonmedicinal as to source

ICD-10-CM codes T51-T65 cover toxic effects of substances chiefly nonmedicinal as to source, within injury, poisoning and certain other consequences of external causes. The block holds 2,406 codes across 15 categories, of which 1,632 are billable and 774 are header codes that cannot be submitted on a claim. 2,406 of them (100%) require a 7th character.

Excludes1 — never code together

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

contact with and (suspected) exposure to toxic substances (Z77.-)

Use additional code

Add a secondary code to capture the detail described below.

code(s):
for all associated manifestations of toxic effect, such as: respiratory conditions due to external agents (J60-J70)
personal history of foreign body fully removed (Z87.821)
to identify any retained foreign body, if applicable (Z18.-)

Notes

Additional guidance from the ICD-10-CM tabular list.

When no intent is indicated code to accidental. Undetermined intent is only for use when there is specific documentation in the record that the intent of the toxic effect cannot be determined.

The 7th character in T51-T65

A code in this block is not complete without its 7th character, and a missing one is a rejected claim rather than a denied one: the clearinghouse never passes it on. 2,406 of the 2,406 codes here take one.

A: initial encounter
D: subsequent encounter
S: sequela

Risk adjustment in T51-T65

0 codes in this block map to a CMS-HCC, which means the diagnosis carries a risk-adjustment payment when it is documented and coded. Under-coding here is money left on the table; over-coding here is what audits are for.

HCC 155 Major Depression, Moderate or Severe, without Psychosis

What else to watch in T51-T65

1,632 codes are named in Medicare coverage policies. An LCD or NCD lists them as supporting medical necessity, or explicitly as not supporting it. Which applies depends on the MAC for your state.