2026 ICD-10-CM Diagnosis Code P71.2Neonatal hypomagnesemia

ICD-10-CM Codes›P00–P96›P70-P74›P71

ICD-10-CM P71.2
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

P71.2 is a billable ICD-10-CM diagnosis code for neonatal hypomagnesemia. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026) and groups to MS-DRG 791, 793. As a secondary diagnosis, it counts as a complication or comorbidity (CC) and moves an inpatient stay to a higher severity level within its MS-DRG family. It does not count, however, when the principal diagnosis is one of 44 closely related codes. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Other specified and unspecified perinatal conditions.

Code Identity

ICD-10-CM Code
P71.2
Billable Status
Yes — Valid for Submission
Code Describes
Neonatal hypomagnesemia
Short Description
Neonatal hypomagnesemia
Same as the full description in the CMS dataset.
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 CodeP71.2Neonatal hypomagnesemia

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Autosomal dominant primary hypomagnesemia with hypocalciuria
  • Familial hypomagnesemia hypercalciuria nephrocalcinosis with severe ocular involvement
  • Familial hypomagnesemia-hypercalciuria
  • Familial primary hypomagnesemia with hypercalciuria and nephrocalcinosis
  • Familial primary hypomagnesemia with hypercalciuria and nephrocalcinosis without severe ocular involvement
  • Familial primary hypomagnesemia with normocalciuria
  • Familial primary hypomagnesemia with normocalciuria and normocalcemia
  • Hypocalciuria
  • Hypomagnesemia
  • Hypomagnesemia co-occurrent with normocalciuria
  • Hypomagnesemic tetany in newborn
  • Neonatal hypomagnesemia
  • Primary hypomagnesemia
  • Tetany

Index to Diseases and InjuriesGuidance

Alphabetical index entries that point to this code.

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

  • Tetany

    a disorder characterized by muscle twitches, cramps, and carpopedal spasm, and when severe, laryngospasm and seizures. this condition is associated with unstable depolarization of axonal membranes, primarily in the peripheral nervous system. tetany usually results from hypocalcemia or reduced serum levels of magnesium that may be associated with hyperventilation; hypoparathyroidism; rickets; uremia; or other conditions. (from adams et al., principles of neurology, 6th ed, p1490)

  • Grade 1 Hypomagnesemia, CTCAE|Grade 1 Hypomagnesemia

  • Grade 2 Hypomagnesemia, CTCAE|Grade 2 Hypomagnesemia

    <1.2 - 0.9 mg/dl; <0.5 - 0.4 mmol/l

  • Grade 3 Hypomagnesemia, CTCAE|Grade 3 Hypomagnesemia

    <0.9 - 0.7 mg/dl; <0.4 - 0.3 mmol/l

  • Tetany

    sudden and involuntary contraction of a muscle of group of muscles due to hypocalcemia.

  • Familial Primary Hypomagnesemia

    a hereditary disorder that leads to a selective defect in renal or intestinal magnesium absorption, resulting in a low serum magnesium concentration.

  • Grade 1 Hypomagnesemia, CTCAE|Grade 1 Hypomagnesemia

  • Grade 2 Hypomagnesemia, CTCAE|Grade 2 Hypomagnesemia

    <1.2-0.9 mg/dl; <0.5-0.4 mmol/l

  • Grade 3 Hypomagnesemia, CTCAE|Grade 3 Hypomagnesemia

    <0.9-0.7 mg/dl; <0.4-0.3 mmol/l

  • Grade 4 Hypomagnesemia, CTCAE|Grade 4 Hypomagnesemia

    <0.7 mg/dl; <0.3 mmol/l; life-threatening consequences

  • Grade 5 Hypomagnesemia, CTCAE|Grade 5 Hypomagnesemia

    death

  • Hypomagnesemia

    lower than normal levels of magnesium in the circulating blood.

  • Hypomagnesemia, CTCAE|Hypomagnesemia|Hypomagnesemia

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

  • TRPM6 wt Allele|CHAK2|FLJ22628|HMGX|HOMG|HOMG1|HSH|Hypomagnesemia, Secondary Hypocalcemia Gene|Transient Receptor Potential Cation Channel Subfamily M Member 6 wt Allele|Transient Receptor Potential Cation Channel, Subfamily M, Member 6 Gene

    human trpm6 wild-type allele is located in the vicinity of 9q21.13 and is approximately 166 kb in length. this allele, which encodes transient receptor potential cation channel subfamily m member 6 protein, is involved in both magnesium homeostasis and protein phosphorylation. mutation of the gene is associated with hypomagnesemia.

  • Nephrocalcinosis

    deposition of calcium in the renal parenchyma, resulting from high levels of calcium in the blood and/or urine.

Patient EducationClinical

Fluid and Electrolyte Balance

Electrolytes are minerals that have an electric charge when they are dissolved in water or body fluids, including blood. The electric charge can be positive or negative. You have electrolytes in your blood, urine (pee), tissues, and other body fluids.

The full article covers:

  • What are electrolytes?
  • What are the different types of electrolytes in your body?
  • What is an electrolyte imbalance?
  • What are the different types of electrolyte imbalances?
  • How are electrolyte imbalances diagnosed?
  • What are the treatments for electrolyte imbalances?

Read the full article at MedlinePlus

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

Convert P71.2 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 P71.2Overview

What is the ICD-10 code for neonatal hypomagnesemia?

The ICD-10-CM code for neonatal hypomagnesemia is P71.2 (sometimes written as P712). It is billable on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

Is P71.2 a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report neonatal hypomagnesemia on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

What MS-DRG does P71.2 group to?

When neonatal hypomagnesemia is the principal diagnosis on an inpatient stay, it groups to MS-DRG 791, 793, with relative weights from 4.0590 to 4.1696 depending on complications. Higher weights mean higher Medicare reimbursement.

Is P71.2 a CC or MCC?

CMS lists P71.2 as a CC (complication or comorbidity) for FY 2026. Reported as a secondary diagnosis, it moves the inpatient stay to a higher-weighted DRG within its severity family. It does not count when the principal diagnosis is one of the 44 closely related codes in its exclusion list.

What is the ICD-9 equivalent of P71.2?

Under the General Equivalence Mappings, neonatal hypomagnesemia converts to ICD-9-CM 775.4 (hypocalcem/hypomagnes NB). The mapping is approximate, so confirm the match fits the documentation.