'Department of Health and Human services, Victoria, Australia'

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Abnormal INR secondary to antibiotics with warfarin use

Publication Date: December 2018

ICD 10 AM Edition: Tenth edition

Query Number: 3406

High INR is clearly documented as being secondary to antibiotics. Warfarin is adjusted accordingly during patient's admission. I have also discussed this with the clinician to support this documentation.

When I code R79.83 Abnormal coagulation profile as an adverse effect of antibiotics and Z92.1 Personal history of long term (current) use of anticoagulants, I have an error appear on the Codefinder referring to ACS0303 - do not assign Z92.1 and R79.83 in the same episode.

There is an excludes note in the tabular under R79.83. There is no causal relationship evident between the increased INR and the warfarin usage and I feel that both these codes are relevant to this episode of care.


As advised in ACS 0303 Abnormal coagulation profile due to anticoagulants and the excludes notes in the Tabular, the codes R79.83 Abnormal coagulation profile and Z92.1 Personal history of long term (current) use of anticoagulants are mutually exclusive and cannot be assigned together.

In the scenario cited, as the INR value is documented as high the correct code to assign is R79.83 Abnormal coagulation profile. As there is a documented relationship between the high INR and antibiotic use, assign Y40.9 Systemic antibiotic, unspecified causing adverse effects in therapeutic use as the external cause code.

Also assign Y44.2 Anticoagulants in accordance with the use additional code note at R79.83 Abnormal coagulation profile and the second dot point in the classification section of ACS 0303 Abnormal coagulantion profile due to anticoagulants.