P74.421 ICD-10-CM Code: Hyperchloremia of newborn

Coding instructions

Official Tabular Instructional Notes: the inclusion, exclusion and sequencing notes published for P74.421 in the official ICD-10-CM tabular list, quoted as published.

Source: CMS/CDC — ICD-10-CM Tabular ListRelease: FY2026Effective: October 1, 2025

Notes without a marker are published on P74.421 itself; “inherited from” names the category or block whose note applies here.

Coder workflow for P74.421

MedCoder structured workflow — derived from this code’s own official record

Documentation check

The provider’s diagnostic statement

Codes are assigned from the provider’s documented diagnosis, not from clinical criteria, test values or a medication list (Guidelines I.A.19).

Official instructions as workflow

• Excludes2 — not part of P74.421(1 note)

  Coding workflow: The conditions named in this note are not included in P74.421. When the record documents both, both may be reported; the note is a boundary, not a prohibition.

  CompareP74.0

  See the official tabular notes · Guidelines I.A.12.b

Every row is derived from this code’s own record — its title, tabular notes, 7th-character family and same-category siblings — with fixed MedCoder wording; nothing is inferred about a patient. The official notes and guideline text are in the sections each row links to, and they control.

Indexed Clinical Terms (3)

Official source data — entries quoted as published, in the Index’s own lookup phrasing

Clinical term phrases from the official ICD-10-CM Index to Diseases and Injuries that map to this code. These are alphabetic-index entries shown as the Index writes them — lookup phrasing, not necessarily the wording of a final diagnosis.

• Acidosis (lactic), metabolic NEC, hyperchloremic, of newborn
• Disturbance (s), electrolyte, newborn, transitory, hyperchloremia
• Disturbance (s), electrolyte, newborn, transitory, hyperchloremic metabolic acidosis

Don’t confuse P74.421 with…

MedCoder analysis — pairs from this code’s official notes, distinctions written by MedCoder

The codes most likely to be picked instead of P74.421 — named in its own official notes, or sharing its laterality or encounter family — with what separates them and which documentation moves the case. Each links to the full comparison.

• P74.0— Excludes2 relationship (Informational)

  Distinct conditions — both may be reported.

  A distinct condition — both may be reported when both are documented.

  What moves you there: Documentation of late metabolic acidosis of the newborn adds P74.0; it is not part of this code and both may be reported when both are documented.

  Full comparison: P74.421 vs P74.0 →

Relationships are read from this code's own official notes, its laterality siblings and its encounter family; the wording of each distinction is MedCoder editorial, and the documentation named in each “what moves you there” line is the official note phrase or sibling title itself. Source: CMS ICD-10-CM tabular instructional notes; ICD-10-CM Official Guidelines, Section I.A.12.a.

Verify Before Coding

• No Medicare Code Editor or MS-DRG Definitions Manual restrictions apply to this code.

From the code registry, the Medicare Code Editor, and the MS-DRG Definitions Manual. Check it against a full claim in Claim Check.

Relationships & Classification

MedCoder structured relationships — computed from published CMS and AHRQ datasets

Other codes that name P74.421 or its code family, from the CMS ICD-10-CM tabular instructional notes. Tabular-note edges are stored at the code family level that carries each note.

Referenced by 1 Excludes2 note: P00 — Newborn affected by maternal conditions that may be unrelated to present pregnancy (via P74.-).

These codes’ tabular lists name this diagnosis as distinct — both may be reported when both are documented.

MS-DRG Grouper Relationships (FY2026)

Potential MS-DRG participation — not a DRG assignment.

FY2026 MS-DRG: not on the CMS CC/MCC list — as a secondary diagnosis this code does not change MS-DRG severity for that release.

Named in the grouper logic of 2 MS-DRGs: DRG 791 (MDC 15), DRG 793 (MDC 15).

From the CMS MS-DRG Definitions Manual (Appendices B and C). Actual DRG assignment depends on the complete claim.

Clinical classification (AHRQ CCSR):PNL013 — Other specified and unspecified perinatal conditions (default).

Clinical Classifications Software Refined (CCSR) for ICD-10-CM Diagnoses. Healthcare Cost and Utilization Project (HCUP), Agency for Healthcare Research and Quality.

Related Codes

Same clinical category (CCSR)

AHRQ's Clinical Classifications Software groups these diagnoses under the same clinical category (Other specified and unspecified perinatal conditions).

P74.0 — Late metabolic acidosis of newborn, P74.1 — Dehydration of newborn, P74.2 — Disturbances of sodium balance of newborn, P74.21 — Hypernatremia of newborn, P74.22 — Hyponatremia of newborn, P74.3 — Disturbances of potassium balance of newborn, P74.31 — Hyperkalemia of newborn, P74.32 — Hypokalemia of newborn, P74.4 — Other transitory electrolyte disturbances of newborn, P74.41 — Alkalosis of newborn, P74.422 — Hypochloremia of newborn, P74.49 — Other transitory electrolyte disturbance of newborn, P74.5 — Transitory tyrosinemia of newborn, P74.6 — Transitory hyperammonemia of newborn, P74.8 — Other transitory metabolic disturbances of newborn, P74.9 — Transitory metabolic disturbance of newborn, unspecified, P80.0 — Cold injury syndrome, P80.8 — Other hypothermia of newborn, P80.9 — Hypothermia of newborn, unspecified, P81.0 — Environmental hyperthermia of newborn, +74 more

Same Index main term, other category

The ICD-10-CM Index to Diseases and Injuries files this code under the main terms “Disturbance”, “Acidosis”; these codes share that main term but sit in a different category of the Tabular List.

N25.89 — Other disorders resulting from impaired renal tubular function (renal), N85.8 — Other specified noninflammatory disorders of uterus (innervation uterus), O08.5 — Metabolic disorders following an ectopic and molar pregnancy (metabolism, with, molar pregnancy), O75.89 — Other specified complications of labor and delivery (metabolism, in labor or delivery), P70.8 — Other transitory disorders of carbohydrate metabolism of newborn (metabolism, neonatal, transitory, carbohydrate metabolism, specified type NEC), P70.9 — Transitory disorder of carbohydrate metabolism of newborn, unspecified (metabolism, neonatal, transitory, carbohydrate metabolism), P71.8 — Other transitory neonatal disorders of calcium and magnesium metabolism (metabolism, neonatal, transitory, calcium and magnesium, specified type NEC), P71.9 — Transitory neonatal disorder of calcium and magnesium metabolism, unspecified (metabolism, neonatal, transitory, calcium and magnesium), P72.8 — Other specified transitory neonatal endocrine disorders (endocrine, neonatal, transitory, specified NEC), P72.9 — Transitory neonatal endocrine disorder, unspecified (endocrine, neonatal, transitory), P81.8 — Other specified disturbances of temperature regulation of newborn (temperature, regulation, newborn, specified NEC), P81.9 — Disturbance of temperature regulation of newborn, unspecified (temperature, regulation, newborn), P84 — Other problems with newborn (newborn), P91.88 — Other specified disturbances of cerebral status of newborn (cerebral, status, newborn, specified NEC), P91.9 — Disturbance of cerebral status of newborn, unspecified (cerebral, status, newborn), R20.0 — Anesthesia of skin (sensation NEC, skin, anesthesia), R20.1 — Hypoesthesia of skin (sensation NEC, skin, hypoesthesia), R20.2 — Paresthesia of skin (sensation NEC, skin, paresthesia), R20.3 — Hyperesthesia (sensation NEC, skin, hyperesthesia), R20.8 — Other disturbances of skin sensation (temperature, sense), +133 more

Contextual Map

Every relationship of P74.421 in one view: hierarchy, official tabular instructions in both directions, clinical classification, risk adjustment, MS-DRG participation, index terms and change history — each edge carrying the CMS source it derives from.

Run P74.421 with these 2 related codes in Claim Check

Hierarchy

• P00-P96 — Chapter 16: Certain Conditions Originating in the Perinatal Period (P00-P96) (P00-P96)[Hierarchy]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• P70-P74 — Transitory endocrine and metabolic disorders specific to newborn[Hierarchy]— CMS ICD-10-CM tabular structure · icd10cm-fy2026

Excludes2

• P74.0 — Late metabolic acidosis of newborn[Excludes2]: “late metabolic acidosis of the newborn (P74.0)”— CMS ICD-10-CM tabular instructional notes · icd10cm-fy2026

Referenced by Excludes2 notes

• P00 — Newborn affected by maternal conditions that may be unrelated to present pregnancy[Excludes2](via P74.-): “newborn affected by maternal endocrine and metabolic disorders (P70-P74)”— CMS ICD-10-CM tabular instructional notes · icd10cm-fy2026

Clinical classification (CCSR)

• PNL013 — Other specified and unspecified perinatal conditions[CCSR]— AHRQ CCSR for ICD-10-CM Diagnoses (HCUP)

MS-DRG Grouper

• DRG 791 — PREMATURITY WITH MAJOR PROBLEMS[MS-DRG]: “PREMATURITY WITH MAJOR PROBLEMS (MDC 15)”— CMS MS-DRG Definitions Manual (Appendix B) · FY2026
• DRG 793 — FULL TERM NEONATE WITH MAJOR PROBLEMS[MS-DRG]: “FULL TERM NEONATE WITH MAJOR PROBLEMS (MDC 15)”— CMS MS-DRG Definitions Manual (Appendix B) · FY2026

MDC crossing

• MDC 15 — Newborns and Other Neonates with Conditions Originating in Perinatal Period[MDC crossing]: “Newborns and Other Neonates with Conditions Originating in Perinatal Period — the grouper's crossing between diagnoses and procedures: a principal diagnosis sets the MDC, and same-MDC procedures move the stay to its surgical DRGs.”— CMS MS-DRG Definitions Manual · FY2026

Index entries

• Acidosis (lactic), metabolic NEC, hyperchloremic, of newborn[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026
• Disturbance (s), electrolyte, newborn, transitory, hyperchloremia[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026
• Disturbance (s), electrolyte, newborn, transitory, hyperchloremic metabolic acidosis[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026

Nearest codes (18)

• P74 — Other transitory neonatal electrolyte and metabolic disturbances[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• P74.0 — Late metabolic acidosis of newborn[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• P74.1 — Dehydration of newborn[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• P74.2 — Disturbances of sodium balance of newborn[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• P74.21 — Hypernatremia of newborn[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• P74.22 — Hyponatremia of newborn[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• P74.3 — Disturbances of potassium balance of newborn[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• P74.31 — Hyperkalemia of newborn[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• and 10 more

Change history

• FY2019 — Added to the code set[Change history]— CMS release files (code change ledger) · icd10cm-fy2019

Sources for this page

Codes, titles, notes, index terms and mappings on this page are transcribed from the datasets below. Relationships MedCoder computed and text MedCoder wrote are labelled where they appear.

Code, title, tabular notes and index terms Official source data

CMS/CDC ICD-10-CM FY2026 tabular list, index and tables, effective October 1, 2025 Release, file and checksum · Publisher’s page

Claim edits Official source data

CMS Definitions of Medicare Code Edits — v43.1 (April 2026) Release, file and checksum · Publisher’s page

Inpatient payment groups Official source data

CMS MS-DRG Definitions Manual (incl. Appendix B diagnosis index, Appendix C CC/MCC list, Appendix E procedure index) and IPPS Final Rule tables — v43 Release, file and checksum · Publisher’s page

Change history and date-of-service validity Official source data

CMS ICD-10-CM release addenda, ingested release by release into the change ledger Release, file and checksum · Publisher’s page

Comparisons, relationships and the contextual map MedCoder structured relationship

Computed by MedCoder from the tabular notes and tables above; every derived relationship is marked as derived where it appears

Summary and FAQ answers MedCoder explanation

Written by MedCoder to explain the sources above: drafted with AI assistance, checked by a person against the release files, and labelled as MedCoder text where it appears. Not official text.

Labels on this page: Official source data · MedCoder structured relationship · MedCoder explanation. How to read the labels · All data sources and release dates

Nearest Codes in This Family

Official ICD-10-CM classifications closest to P74.421 in its code family, with their registry titles.

• P74.31 — Hyperkalemia of newborn
• P74.32 — Hypokalemia of newborn
• P74.4 — Other transitory electrolyte disturbances of newborn
• P74.41 — Alkalosis of newborn
• P74.42 — Disturbances of chlorine balance of newborn
• P74.422 — Hypochloremia of newborn
• P74.49 — Other transitory electrolyte disturbance of newborn
• P74.5 — Transitory tyrosinemia of newborn
• P74.6 — Transitory hyperammonemia of newborn
• P74.8 — Other transitory metabolic disturbances of newborn

View all codes in the P74 family