CurrentMedical Mutual - OhioPolicy AHS - M2141 - Testing of Homocysteine Metabolism-Related Conditions, 1

Testing of Homocysteine Metabolism-Related Conditions

Clinical coverage criteria for laboratory testing related to homocysteine metabolism (newborn screening, diagnostic and monitoring tests for homocystinuria and related disorders) for Medical Mutual - Ohio members.

Policy Summary

PayerMedical Mutual - Ohio

PolicyTesting of Homocysteine Metabolism-Related Conditions

Policy CodePolicy AHS - M2141 - Testing of Homocysteine Metabolism-Related Conditions, 1

Change TypeLiterature review (no coverage changes)

Effective DateDec 12, 2016

Next Review Date

Key ActionWhen a newborn methionine result exceeds the cut-off, submit a repeat dried blood specimen to the newborn screening program or obtain quantitative plasma amino acid analysis and plasma total homocysteine; order plasma total homocysteine for adults with suspected CBS deficiency and for monitoring therapy, and avoid/plans for denial of plasma free homocysteine testing as it is not covered.

SourceLink

POLICY UPDATE CHANGES

Background, guidelines and recommendations, and evidence-based scientific references were updated on 12/04/2024 without modifying coverage criteria.

1Covered: Pyridoxine (B6) challenge test for phenotype diagnosis

1Covered: Plasma total homocysteine for adult diagnosis/monitoring

1Not covered: Plasma free homocysteine testing

Trek Health ingests and normalizes Transparency in Coverage data and payer policy updates to give provider organizations a clear view of how commercial reimbursement behaves across markets, payers, and services. Our platform transforms raw payer disclosures into structured intelligence that supports contract evaluation, payer negotiations, and service line strategy. By combining market benchmarks with ongoing policy visibility, Trek helps teams identify variability, risk, and opportunity in commercial reimbursement. The result is faster insight, stronger negotiating positions, and more informed financial decisions.

When Testing for Homocysteine-Related Conditions Is Covered

Newborn Screening — Covered

Newborn screening for homocysteine-related conditions MEETS COVERAGE CRITERIA in any of the following situations:

ANY of the following

Screening for classic homocystinuria due to CBS deficiency by performing quantitative plasma amino acids analysis and/or plasma or urine total homocysteine analysis.
Screening for homocystinuria in dried blood spots.
Screening for hypermethioninemia in dried blood spots.

Follow-up after abnormal newborn screen — Covered

When the initial newborn screening test result exceeds the cut-off level of methionine, coverage meets criteria for the following:

ANY of the following

Repeat dried blood specimen submitted to the newborn screening program.
Quantitative plasma amino acid analysis and analysis of plasma total homocysteine.

Pyridoxine (B6) challenge test — Covered

For diagnosis of phenotype variants of classic homocystinuria due to CBS deficiency:

ALL of the following must be met

Pyridoxine (B6) challenge test to determine B6-responsive vs B6-nonresponsive phenotypes.

Adult diagnostic and monitoring testing — Covered

Total homocysteine testing in plasma MEETS COVERAGE CRITERIA when any of the following apply:

ANY of the following

Individuals over 18 years of age with homocystinuria suspected to be caused by CBS deficiency.
Monitoring therapy in individuals with confirmed CBS deficiency.

Plasma free homocysteine testing — Not covered

ALL

Plasma free homocysteine testing DOES NOT MEET COVERAGE CRITERIA.

Diagnostic and control thresholds

Total homocysteine (tHcy) - neonate50 to >100 µmol/L

Total homocysteine (tHcy) - untreated older individual>100 µmol/L

Total homocysteine (tHcy) - control<15 µmol/L

Methionine (plasma) - neonate with homocystinuria200-1500 µmol/L (3-23 mg/dL)

Methionine (plasma) - untreated older individual>50 µmol/L (>0.7 mg/dL)

Methionine (plasma) - control10-40 µmol/L (0.2-0.6 mg/dL)

Applicable Procedure Codes

Applicable Procedure Codes (listed in policy)CPT

82136	Amino acids, 2 to 5 amino acids, quantitative, each specimen
82139	Amino acids, 6 or more amino acids, quantitative, each specimen
82615	Cystine and homocysteine, urine, qualitative
83090	Homocysteine
83921	Organic acid, single, quantitative
84207	Pyridoxal phosphate (Vitamin B-6)

What Providers Must Do / Billing Impacts

Documentation Required

Follow-up of abnormal newborn methionine screen

When the newborn methionine level exceeds the program cut-off, submit a repeat dried blood specimen to the newborn screening program or obtain quantitative plasma amino acid analysis and plasma total homocysteine for follow-up diagnostic evaluation.

82136
82139
83090

Documentation Required

Use of pyridoxine challenge

Perform a pyridoxine (vitamin B6) challenge to determine pyridoxine responsiveness for phenotype classification in suspected cystathionine-β-synthase (CBS) deficiency.

84207
83090

Clinical Background and Rationale

Homocystinuria is a metabolic disorder—most commonly genetic but occasionally acquired—characterized by accumulation of homocysteine and methionine due to defects in the transsulfuration or remethylation pathways. The most frequent cause of classic homocystinuria is deficiency of the enzyme cystathionine-β-synthase (CBS); defects in remethylation pathway genes (for example, MTHFR, MTR, MTRR, or MMADHC) and severe vitamin B12 deficiency can also produce similar biochemical abnormalities and clinical findings. Clinical features of CBS deficiency can include ocular lens dislocation, skeletal abnormalities, thromboembolic events, and developmental delay, with variable severity depending on the underlying mutation and treatment responsiveness.

Measurement of total homocysteine (tHcy) in plasma is the frontline diagnostic analyte for suspected homocystinuria. Typical reference thresholds used in diagnosis are: control tHcy <15 µmol/L, neonate with homocystinuria 50 to >100 µmol/L, and an untreated older individual >100 µmol/L. Methionine measurement on quantitative plasma amino acid analysis provides corroborating evidence (e.g., neonatal methionine often 200–1500 µmol/L in affected infants). Dried blood spot testing for tHcy or methionine (including Met:Phe ratio and second-tier tHcy) is widely used in newborn screening programs and offers practical stability and acceptable correlation with plasma tHcy for screening purposes.

Determination of pyridoxine (vitamin B6) responsiveness—performed as a pyridoxine (B6) challenge test—is essential to classify CBS-related phenotypes. Patients who are B6-responsive typically have a milder clinical course and later onset, and monitoring targets differ by responsiveness: E-HOD guidance recommends targeting tHcy <50 µmol/L in pyridoxine-responsive patients and approximately 120 µmol/L total homocysteine (corresponding to ~11 µmol/L free Hcy) for pyridoxine-unresponsive patients. Plasma free homocysteine testing is not recommended in place of tHcy because it is less sensitive and not reproducible at lower concentrations.

Key Terms

Key definitions

tHcyTotal homocysteine (sum of all forms of homocysteine in plasma).

CBSCystathionine β-synthase, enzyme deficient in classic homocystinuria.

B6-responsivePhenotype of CBS deficiency in which pyridoxine (vitamin B6) lowers homocysteine and improves clinical course.

Policy Updates

12/04/2024revisedLatest

Background, guidelines and recommendations, and evidence-based scientific references were updated following a literature review; no coverage criteria were modified.

Testing of Homocysteine Metabolism-Related Conditions

When Testing for Homocysteine-Related Conditions Is Covered

Applicable Procedure Codes

What Providers Must Do / Billing Impacts

Clinical Background and Rationale

Key Terms

Other Policies to Read With This One

Policy Updates