Changes to the International Classification of Diseases, 10th Edition, Clinical Modification (ICD-10-CM) occur every year, and for 2025, the update includes 252 new codes, 36 code deletions and 13 code revisions.5 The fact that these codes are for 2025 can be misleading because their implementation occurs on October 1, 2024; there is no grace period, and claims will reject for incorrect coding.
This year’s changes are overwhelmingly of clarification: adding/modifying exclusions and synonyms, and adding/changing coding instructions. Exclusions, as you may recall, come in two varieties: Excludes1 are mutually exclusive codes; this means that the selected code cannot be coded with another containing an Excludes1. Examples of Excludes1 are E10.- Type 1 diabetes mellitus and O24.2- Gestational diabetes. The patient can have one or the other, but not both. Excludes2 notations represent conditions that may be coded together. Examples of Excludes2 are I12- Hypertensive chronic kidney disease and N17.- Acute kidney failure.
Given the proliferation of online sources for ICD-10 codes, all coding staff are reminded to use the ICD-10-CM index, tabular and other books, freely available from CMS. They contain all the exclusions and coding notations. Googling a code only scratches the surface in the world of coding and most online sources will not provide coding guidelines.
The chapters identified below contain code additions.2
Chapter 2: Lymphoma codes now have the fifth character A, denoting remission. See C81 Hodgkin lymphoma; C82 Follicular lymphoma; C83 Non-follicular lymphoma (these include B-cell & mantle-cell); C84 Mature T/NK-cell lymphomas; and C85 Other specified and unspecified types of non-Hodgkin lymphoma (this includes non-Hodgkin lymphoma).
Other lymphoma codes now distinguish between not having achieved remission and in remission. Those are: C86 Other specified types of T/NK-cell lymphoma, and C88 Malignant immunoproliferative diseases and certain other B-cell lymphomas.
Chapter 3: The only new code in this chapter is under aplastic anemia: D61.03 Fanconi anemia.
Chapter 4: This section saw some interesting changes, with two new codes for less common conditions (E74.82- and E88.82). However, big changes occurred in the following areas:
E10.A Type 1 diabetes mellitus, presymptomatic, which has additional definition as to stage 1, stage 2 or unspecified stage. An article in the October 1, 2015 issue of Diabetes Care defines this condition as, “an immune-mediated loss of functional pancreatic β-cell mass, leading to symptomatic diabetes and lifelong insulin dependence.” In short, a patient may have antibodies that herald the onset of T1D but may be asymptomatic and still producing insulin. Read more about the stages here.3
For any codes that refer to hypoglycemia (e.g., E10.64 Type 1 diabetes mellitus with hypoglycemia, etc.), a level is required, as applicable. Use E16.A Hypoglycemia level: E16.A1 for Level 1 (generally defined as a glucose level between <70 mg/dl and ≥54 mg/dl), E16.A2 for Level 2 (generally defined as a glucose level <54 mg/dl), E16.A3 for Level 3 (generally defined as a severe event characterized by altered mental and/or physical status requiring assistance.). 4
Obesity codes (E66.8) will require additional coding for class: E66.811 for Class 1 (generally defined as BMI 30-34.9%), E66.812 for Class 2 (generally defined as BMI 35-39.9%), and E66.813 for Class 3 [severe] (generally defined as BMI 40+)1. It’s important to note that, heretofore, a BMI of 40+ (or 35+ with specific comorbidities) has been characterized as E66.01 Morbid obesity. E66.01 continues to be a risk adjusted code, while E66.813 is not in the CMS-HCC model as of this writing. Coders are advised to code based on the clinician’s documentation and to educate providers on the distinctions between E66.813 and E66.01, which should contain additional documentation beyond the BMI to support morbid obesity.
Chapter 5: Eating disorders saw great expansion with severity qualifiers such as mild, moderate, severe, in remission and unspecified [severity] for F50.0 Anorexia nervosa, F50.2 Bulimia nervosa, F50.8 Other eating disorders, including binge eating. Pica and rumination in adults have now have specific codes.
Chapter 6: G40.8 Other epilepsy and recurrent seizures expanded to include a few codes for G40.84 KCNQ2-related epilepsy. Other disorders of the nervous system (G89-G99) grew to include specific codes for Serotonin syndrome (G90.81) and other disorders of the autonomic nervous system (G90.89) as well as a new code for developmental and epileptic encephalopathy (G93.45).
Chapter 9: Surprisingly little coding growth occurred in the diseases of the circulatory system with only five new codes added to I26.0 for greater definition of pulmonary emboli.
Chapter 10: J34.8 Other specified disorders of nose and nasal sinuses grew to include new codes for different types of nasal valve collapse.
Chapter 11: Several new codes were added to K60.3 Anal fistula, K60.4 Rectal fistula and K60.5 Anorectal fistula to further characterize their status: simple or complex; initial, persistent or recurrent; and unspecified.
Chapter 12: This chapter welcomed a few new codes, expanding pruritus (L29) and qualifying cicatricial alopecia (L66).
Chapter 13: M51 added codes allowing for greater characterization of pain with disc degeneration: with back pain only, with lower extremity pain only, with back & LE pain and without mention of back or LE pain. Synovitis and tenosynovitis (M65.9) added codes for specific location and laterality.
Chapter 17: Definitions of congenital aortic and mitral valve malformations (Q23.8-) are new this year, as is the code for Kleefstra syndrome (Q87.86).
Chapter 18: Anosognosia is a new code (R41.85) in this chapter.
Chapter 19: Two coding categories underwent changes, specifically: T45.A Poisoning by, adverse effect of and underdosing of immune checkpoint inhibitors and immunostimulant drugs and T81.32 Disruption of internal operation (surgical) wound, not elsewhere classified.
Chapter 21: Z15 Genetic susceptibility to disease added specific codes for susceptibility to epilepsy and neurodevelopmental disorders (Z15.1) and obesity (Z15.2). The category for Estrogen, and other hormones and factors receptor status (Z17) grew to include codes for specific hormones. New codes now exist for Encounter for sepsis aftercare (Z51.A); for social determinants of health related to insufficient insurance coverage (Z59.71) and welfare support (Z59.72); and pediatric BMI (Z68.5-).
Z86.010 Personal history of colon polyps was expanded to reflect the types of polyps, and Z92.2 Personal history of drug therapy was divided into history of monoclonal drug therapy and immune checkpoint inhibitor therapy.
In summary, given that the majority of our firm’s clients are primary care providers, the scope of the 2025 changes is relatively small, but the new endocrine codes are certainly worth noting. Finally, since new codes go into effect on October 1, 2024, medical practices should ensure their coding and provider staff are educated on them and that the EMR will automatically load new codes on time to prevent rejected claims or encounters.
Sources:
- Centers for Disease Control & Prevention1
- Centers for Medicare & Medicaid Services2
- Diabetes Care Journal, Volume 38, Issue 103
- Clinical Diabetes Journal, Volume 35, Issue 24
- American Academy of Professional Coders (AAPC)5