CurrentCentenePolicy CP MP.121

Clinical Policy: Homocysteine Testing

Defines medical necessity criteria for homocysteine testing (serum/urine) for suspected homocystinuria due to cystathionine beta-synthase deficiency and lists indications for which testing is not proven to improve outcomes; includes ICD-10/CPT coding implications and historical revisions.

Policy Summary

PayerCentene

PolicyClinical Policy: Homocysteine Testing

Policy CodePolicy CP MP.121

Change TypeAnnual review; revisions and coding updates noted (03/25, 03/24, 05/20-05/21).

Effective DateMar 1, 2025

Next Review Date

Key ActionDocument the clinical indication meeting criteria for suspected homocystinuria (family history, markedly elevated serum/urine homocysteine, or listed characteristic physical findings) in the medical record to support medical necessity.

POLICY UPDATE CHANGES

Annual review March 2025: background updated and references reviewed/updated with no impact to criteria.

Revisions in 03/24 expanded criteria to include first-degree relative, markedly elevated serum/urine homocysteine, and specific characteristic physical findings including developmental delay, marfanoid appearance, osteoporosis, ocular abnormalities, thromboembolic disease, and severe premature atherosclerosis.

Changed policy statement to state that homocysteine testing has not been proven to improve outcomes for listed indications (replacing prior 'investigational' language).

1CPT code referenced

~20Not medically necessary ICD-10 codes listed or referenced

Characteristic findings that qualify

Coverage Summary

This policy defines medical necessity criteria for serum or urine homocysteine testing focused on suspected homocystinuria due to cystathionine beta-synthase deficiency and lists indications for which testing is not proven to improve outcomes.

Scope includes requirements to document clinical indications that meet criteria (family history, markedly elevated serum/urine homocysteine, or characteristic physical findings) and identifies indications considered not proven to improve outcomes such as cardiovascular risk testing, dementia, and borderline or discordant vitamin B12 deficiency.

Policy metadata and thresholds

policy_numberCP MP.121

subjectHomocysteine Testing

statusCURRENT

effective_date2025-03-01

last_review_date2025-03-01

plasma_homocysteine_categoriesBasal 5–15 µmol/L; moderate 15–30 µmol/L; intermediate 30–100 µmol/L; severe >100 µmol/L

Medical Necessity Criteria

Medically Necessary

Homocysteine testing is medically necessary for members/enrollees with suspected homocystinuria caused by cystathionine beta-synthase deficiency including ONE or more of the following:

ANY of the following

First-degree relative with homocystinuria
Markedly elevated serum and urine homocysteine
Characteristic physical findings (ONE of)
- Developmental delay
- Marfanoid appearance

Coding

Relevant CPTCPT

83090

Homocysteine

Not Medically Necessary ICD-10 Codes (listed)ICD-10Not Covered

F01.52	Vascular dementia, unspecified severity, with agitation
F01.5?	Vascular dementia variations (behavioral/psychotic/mood/anxiety disturbances)
F03.9	Unspecified dementia, unspecified severity
F03.A4	Vascular dementia mild with anxiety (as listed)
F03.B4	Unspecified dementia moderate with agitation (as listed)
F03.C1	Vascular dementia moderate with anxiety (as listed)
F03.C4	Unspecified dementia severe with agitation (as listed)
G30.0	Alzheimer's disease with early onset
G30.1	Alzheimer's disease with late onset
G30.8	Other Alzheimer's disease

1–10 of 20

1/2

mixed

No codes listed

Provider Actions

Documentation Required

Indication documentation required

Document the clinical indication in the medical record showing the member meets criteria for suspected homocystinuria due to cystathionine beta‑synthase deficiency to support medical necessity.

83090
First‑degree relative with homocystinuria
Markedly elevated serum and urine homocysteine
Characteristic physical findings (developmental delay; marfanoid appearance; osteoporosis; ocular abnormalities such as ectopia lentis; thromboembolic disease; severe premature atherosclerosis)

Denial Risk

Claims for listed not medically necessary indications may be denied

Background and Evidence

Homocysteine is an intermediary amino acid generated during conversion of methionine to cysteine; mutations in enzymes that regulate homocysteine homeostasis (for example, cystathionine beta-synthase and MTHFR) can lead to elevated levels and are associated with thrombotic risk and other disease associations.

Homocystinuria is a rare inherited condition characterized by severe elevations in plasma and urine homocysteine concentrations, often due to cystathionine beta-synthase deficiency, and can be associated with premature thrombotic events.

B‑vitamin supplementation (folic acid, vitamin B6, and vitamin B12) lowers homocysteine concentrations; meta-analyses show folic acid supplementation produces dose-dependent reductions in plasma homocysteine, but randomized trials and systematic reviews have not demonstrated that lowering homocysteine with B vitamins reduces myocardial infarction, stroke, or death or provides clear benefit for prevention of cognitive decline.

Homocysteine is a sensitive marker for established vitamin B12 deficiency and is used alongside methylmalonic acid (MMA) for diagnosis, but its role is unclear for evaluating borderline or low‑normal B12 status where it would be most useful.

Reference Ranges

Evidence Summary

Homocystinuria: Rare inherited condition with severe elevations in plasma and urine homocysteine, often due to cystathionine beta‑synthase deficiency.

Medicare Determinations

Name	Number	Effective Date
Billing and coding: Homocysteine level, serum	A56675	2019-10-01

Revision History

2005-05-20policy_revision

Changed borderline B12 deficiency and idiopathic VTE/thromboembolism indications from medically necessary to investigational; replaced 'investigational' language in section II with statement that homocysteine testing has not been proven to improve outcomes compared to other technologies (change noted 05/20 and later affirmed).

2005-05-21reaffirmation

Replaced 'investigational' language in section II with statement that homocysteine testing has not been proven to improve outcomes compared to other technologies (approval documented 05/21 reaffirming the change).

2024-03-24material_expansion

Policy Summary

PayerCentene

PolicyClinical Policy: Homocysteine Testing

Policy CodePolicy CP MP.121

Change TypeAnnual review; revisions and coding updates noted (03/25, 03/24, 05/20-05/21).

Effective DateMar 1, 2025

Next Review Date

On This Page

Ocular abnormalities (ectopia lentis)

Thromboembolic disease

Severe premature atherosclerosis

Not Medically Necessary / Not Proven to Improve Outcomes

Homocysteine testing has not been proven to improve outcomes compared to other technologies for the following indications:

ALL of the following

Cardiovascular risk testing
Borderline low or inconclusive Vitamin B12 deficiency or discordant with the clinical picture
Dementia
Idiopathic (unprovoked) venous thromboembolism; recurrent venous thromboembolism; thrombosis occurring at 45 years of age, or thrombosis at an unusual site
Testing for all other conditions not listed as medically necessary

Homocysteine testing performed for indications that are listed as not proven to improve outcomes is considered not medically necessary and claims for these indications may be denied.

Cardiovascular risk testing
Dementia
Borderline low/inconclusive or discordant Vitamin B12 deficiency
Idiopathic (unprovoked) venous thromboembolism; recurrent VTE; thrombosis at age ≤45 or at an unusual site
Testing for all other conditions not listed as medically necessary

Expanded medically necessary criteria to explicitly include: first-degree relative with homocystinuria; markedly elevated serum and urine homocysteine; and characteristic physical findings (one of developmental delay, marfanoid appearance, osteoporosis, ocular abnormalities/ectopia lentis, thromboembolic disease, or severe premature atherosclerosis).

2025-03-25annual_reviewLatest

Annual review: background and references updated with no impact to criteria; coding/table updates in prior revisions replaced a medically necessary ICD-10 table with a Not Medically Necessary ICD-10 table (coded/table changes documented in revision log).