Genetic Testing for Nutrition and Metabolism (G6PD, MTHFR, Other Metabolic Disorders)
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Criteria for medical necessity of specific genetic tests related to nutrition and metabolic disorders (including G6PD variant analysis, MTHFR variant analysis, and other metabolic disorders) for members of Arizona Complete Health/Centene-affiliated plans.
New policy created with criteria incorporated from other policies and 'Investigational' statements changed to 'current evidence does not support…'.
Coverage Criteria for Genetic Testing (Nutrition & Metabolism)
inv-01: G6PD Variant Analysis
Covered only when specific criteria are met:
Diagnosis of G6PD deficiency is achieved by quantitative spectrophotometric analysis or, more commonly, by a rapid fluorescent spot test detecting generation of NADPH from NADP; molecular testing is available but is not routinely used.
inv-02: MTHFR Variant Analysis
Not supported for the listed indications:
ACMG guidance recommends against MTHFR polymorphism testing for these indications.
inv-03: Other Covered Metabolic Disorders
Covered when ALL of the following are met:
Clinical features for a specific disorder may be referenced from GeneReviews, OMIM, Genetics Home Reference, or similar resources.
The list is not exhaustive; testing for other metabolic disorders will be evaluated per the General Approach to Laboratory Testing policy.
Genetic variant analysis for G6PD is not routinely indicated to establish or confirm glucose-6-phosphate dehydrogenase deficiency. Current evidence does not support G6PD variant analysis for all indications. Diagnosis is most commonly made using biochemical testing — specifically, a quantitative spectrophotometric enzyme assay or a rapid fluorescent spot test that detects generation of NADPH from NADP — and molecular testing is generally reserved for specific circumstances rather than routine evaluation.
Targeted MTHFR variant analysis (for example, testing for the 677T or 1298C polymorphisms) is not supported by current evidence for a number of common clinical uses. This includes evaluation of thrombophilia or recurrent pregnancy loss, screening or evaluation of at‑risk relatives, and testing to guide drug metabolism/pharmacogenetic decisions. Professional guidance (e.g., ACMG) recommends against MTHFR polymorphism testing for these indications and such testing should not be ordered routinely for these purposes.
Indications Where Genetic Testing Is Covered
inv-15: Genetic testing to establish or confirm diagnosis of listed rare metabolic disorders when clinical features fit
Genetic testing to establish or confirm diagnosis of listed rare metabolic disorders is covered when clinical features fit:
Where a metabolic disorder is not specifically discussed in this policy, testing will be evaluated according to the General Approach to Laboratory Testing policy. Clinical features may be referenced from GeneReviews, OMIM, or other authoritative resources.
Coding and Billing
| D55.0 | Deficiency of glucose-6-phosphate dehydrogenase |
| E03.9 | |
| E55.9 | |
| E72.12 | |
| E78.2 | |
| E78.5 | |
| E88.9 | |
| N96 | |
| O03 | |
| R53.83 |
Provider Actions and Prior Authorization
Prior Authorization Required
Prior authorization is required for certain genetic testing related to metabolic disorders. Providers must obtain prior authorization before ordering tests when the plan's coverage criteria specify it, including targeted variant analyses that are not routinely supported by evidence.
- Prior authorization required where indicated by the plan's coverage criteria
- Applies to targeted variant analyses and some supplemental genetic tests
Laboratory-first approach for G6PD
Initial testing for suspected G6PD deficiency should use a laboratory-first approach. A quantitative spectrophotometric assay or a rapid fluorescent spot test that detects NADPH generation from NADP is the recommended first-line diagnostic method. Molecular G6PD variant analysis is not supported as a routine first-line test.
- Recommend quantitative spectrophotometric analysis or rapid fluorescent spot test prior to molecular testing
- Molecular G6PD variant analysis is not supported for all indications
Clinical documentation to support testing
Clinical documentation must demonstrate features consistent with the suspected metabolic disorder to support medical necessity for genetic testing. Documentation should reference relevant clinical signs, family history, biochemical testing results, and any guideline-supported indications.
- Provide clinical features consistent with the suspected disorder (signs, symptoms, biochemical findings)
- Include relevant family history and prior test results to justify genetic testing
Denial risk for unsupported variant analyses
There is a risk of claim denial when ordering unsupported targeted variant analyses such as routine G6PD variant analysis or MTHFR targeted variant analysis for general indications (e.g., thrombophilia evaluation, recurrent pregnancy loss, pharmacogenetic assumptions). Such tests are considered not supported by current evidence unless specific criteria and documentation justify medical necessity.
- Denial risk for routine G6PD variant analysis when used instead of recommended enzyme assays
- Denial risk for MTHFR targeted variant analysis for thrombophilia, recurrent pregnancy loss, evaluation of at-risk relatives, or general pharmacogenetic indications
Ordering Requirements
Ordering requirements — include clinical documentation
Orders for genetic testing should be accompanied by documentation of the member's clinical features that are consistent with the suspected metabolic disorder; follow the General Approach to Laboratory Testing policy for additional ordering criteria.
- Include relevant clinical findings in the order to demonstrate medical necessity.
- Refer to the General Approach to Laboratory Testing policy for further ordering requirements.
Frequency Limits and Repeat Testing
Not Covered / Not Supported
Routine G6PD variant analysis and targeted MTHFR variant analysis for the general indications listed (including thrombophilia evaluation, recurrent pregnancy loss, evaluation of at‑risk relatives, and pharmacogenetic testing) are not supported by current evidence and are generally not covered.
Background
G6PD deficiency is typically identified by biochemical assays rather than by molecular testing. A quantitative spectrophotometric analysis or the widely used rapid fluorescent spot test (which measures NADPH generation from NADP) are standard diagnostic methods. While molecular variant analysis for G6PD exists and may be used in select situations, current evidence does not support its routine use to confirm or establish the diagnosis for all clinical indications.
Definitions
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