The ICD-10-CM code for hypomagnesemia is E83.42 (Hypomagnesemia), a billable code reported when a patient has abnormally low serum magnesium levels documented as the specific disorder of magnesium metabolism.
Primary codes
Billable
Billable
Extension
—
7th character
—
POA exempt
No
Coding risks
- Coding based on lab values alone without provider interpretation
Hierarchy
Code comparison
Compare key differences between related codes to select the most specific option.
| Code | Description | Scenario |
|---|---|---|
| E83.42 | Hypomagnesemia | Patient with documented low serum magnesium, confirming hypomagnesemia rather than an elevated or unspecified magnesium disorder. |
| E83.41 | Hypermagnesemia | Patient with documented elevated serum magnesium, distinguishing from deficiency or unspecified magnesium disorders. |
| E83.49 | Other disorders of magnesium metabolism | Documented magnesium metabolism disorder that is specified but not simple hypomagnesemia or hypermagnesemia. |
| E83.40 | Disorders of magnesium metabolism, unspecified | Magnesium metabolism disorder documented without specifying hypomagnesemia, hypermagnesemia, or another defined type. |
Select the most specific code supported by the encounter documentation. More specific codes improve reimbursement accuracy and reduce audit risk.
Code ranges
Disorders of magnesium metabolism
Category covering magnesium imbalances including deficiency, hypomagnesemia, hypermagnesemia, and unspecified disorders of magnesium metabolism.
Metabolic disorders
Broad sub-chapter covering inborn and acquired disturbances of amino acid, carbohydrate, lipid, mineral, and fluid metabolism.
Disorders of calcium metabolism
Category for hypocalcemia, hypercalcemia, and other calcium metabolism disturbances often clinically linked to magnesium status.
Other disorders of fluid, electrolyte and acid-base balance
Category covering sodium, potassium, volume, and acid-base disturbances not classified under specific mineral metabolism codes.
Other abnormal findings of blood chemistry
Category for abnormal laboratory findings of blood chemistry without an established diagnosis of a metabolic disorder.
Coding risks
Avoid these common coding issues when reporting Hypomagnesemia.
Impact
Assigning E83.42 without explicit low magnesium may miscode as hypermagnesemia (E83.41) or unspecified (E83.40).
Mitigation
Consider querying the provider when magnesium direction is absent rather than inferring from replacement orders alone.
Related codes
Ancillary and co-coding
Codes commonly reported with the primary diagnosis on the same claim.
Differential codes
Alternative or commonly confused codes to consider when documentation suggests a different condition than the primary diagnosis.
Frequently asked questions
Use E83.40 only when documentation does not specify hypo- or hypermagnesemia. If hypomagnesemia is stated, E83.42 is required.
References
Compiled from the following authoritative coding references. Last updated 2026-08-04.