2026 ICD-10-CM Diagnosis Code P71.8Other transitory neonatal disorders of calcium and magnesium metabolism

ICD-10-CM Codes›P00–P96›P70-P74›P71

ICD-10-CM P71.8
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

P71.8 is a billable ICD-10-CM diagnosis code for other transitory neonatal disorders of calcium and magnesium metabolism. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026). Coders also document this condition as hypermagnesemia. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Other specified and unspecified perinatal conditions.

Code Identity

ICD-10-CM Code
P71.8
Billable Status
Yes — Valid for Submission
Code Describes
Other transitory neonatal disorders of calcium and magnesium metabolism
Short Description
Oth transitory neonatal disord of calcium & magnesium metab
Parent Code
P71
Transitory neonatal disorders of calcium and magnesium metabolism

Code Classification

ChapterP00–P96Certain conditions originating in the perinatal period
SectionP70-P74Transitory endocrine and metabolic disorders specific to newborn
CategoryP71Transitory neonatal disorders of calcium and magnesium metabolism
This CodeP71.8Other transitory neonatal disorders of calcium and magnesium metabolism

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Hypermagnesemia
  • Idiopathic hypercalcemia
  • Idiopathic hypercalcemia of infancy
  • Infantile hypercalcemia
  • Severe idiopathic hypercalcemia of infancy

Index to Diseases and InjuriesGuidance

Alphabetical index entries that point to this code.

External Cause of Injuries IndexGuidance

References for this code in the External Cause of Injuries Index.

    • Disturbance(s)
      • metabolism
        • neonatal, transitory
          • calcium and magnesium
            • specified type NEC
    • Hypermagnesemia
      • neonatal

Clinical ClassificationClinical

AHRQ’s CCSR groups this code into broader clinical categories.

CCSR PNL013
Other specified and unspecified perinatal conditions
Default principal diagnosis: inpatient Yes · outpatient Yes

Clinical InformationClinical

  • Grade 1 Hypermagnesemia, CTCAE|Grade 1 Hypermagnesemia

    >uln-3.0 mg/dl; >uln-1.23 mmol/l

  • Grade 3 Hypermagnesemia, CTCAE|Grade 3 Hypermagnesemia

    >3.0-8.0 mg/dl; >1.23-3.30 mmol/l

  • Grade 4 Hypermagnesemia, CTCAE|Grade 4 Hypermagnesemia

    >8.0 mg/dl; >3.30 mmol/l; life-threatening consequences

  • Grade 5 Hypermagnesemia, CTCAE|Grade 5 Hypermagnesemia

    death

  • Hypermagnesemia

    higher than normal levels of magnesium in the circulating blood.

  • Hypermagnesemia, CTCAE|Hypermagnesemia|Hypermagnesemia

    a disorder characterized by laboratory test results that indicate an elevation in the concentration of magnesium in the blood.

  • Grade 1 Hypermagnesemia, CTCAE|Grade 1 Hypermagnesemia

    >uln - 3.0 mg/dl; >uln - 1.23 mmol/l

  • Grade 3 Hypermagnesemia, CTCAE|Grade 3 Hypermagnesemia

    >3.0 - 8.0 mg/dl; >1.23 - 3.30 mmol/l

Patient EducationClinical

Metabolic Disorders

Metabolism is the process your body uses to get or make energy from the food you eat. Food is made up of proteins, carbohydrates, and fats. Chemicals in your digestive system break the food parts down into sugars and acids, your body's fuel.

Read the full article at MedlinePlus

Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.

Convert P71.8 to ICD-9-CMHistory

The closest ICD-9-CM equivalents under the General Equivalence Mappings.

ICD-9-CM
775.4 Hypocalcem/hypomagnes NB
Approximate The match is approximate rather than exact.

Code HistoryHistory

FY 2016AddedAdded to the ICD-10-CM code setEffective October 1, 2015, the first year of ICD-10-CM.
FY 2017–2025No changes
FY 2026CurrentCurrent code set, no changesEffective October 1, 2025 through September 30, 2026.

Questions About P71.8Overview

Is P71.8 a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report other transitory neonatal disorders of calcium and magnesium metabolism on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

What is the ICD-9 equivalent of P71.8?

Under the General Equivalence Mappings, other transitory neonatal disorders of calcium and magnesium metabolism converts to ICD-9-CM 775.4 (hypocalcem/hypomagnes NB). The mapping is approximate, so confirm the match fits the documentation.

Footnotes

[1] Not chronic - A diagnosis code that does not fit the criteria for chronic condition (duration, ongoing medical treatment, and limitations) is considered not chronic. Some codes designated as not chronic are acute conditions. Other diagnosis codes that indicate a possible chronic condition, but for which the duration of the illness is not specified in the code description (i.e., we do not know the condition has lasted 12 months or longer) also are considered not chronic.