Homocysteine Test

Excess Homocysteine

The Homocysteine Test is a serum assessment of homocysteine levels. Homocysteine is an amino acid requiring vitamins B12, B6 and folate to break down and metabolize to create other chemicals your body needs. High homocysteine levels may mean you have a vitamin deficiency. Without treatment, elevated homocysteine increases your risks for dementia, heart disease and stroke.

Turnaround Time: 1-2 weeks

Turnaround times are estimates. Detailed order tracking is available in the MosaicDX Portal.

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What Patients Might Benefit from Homocysteine Testing?

There are a number of symptoms and conditions associated with excess homocysteine:

  • Atherosclerosis
  • Certain Cancers
  • Depression
  • Insulin Resistance
  • Metabolic Syndrome
  • Osteoporosis
  • Psychiatric Disorders
  • Schizophrenia
  • Type 2 Diabetes


Why Assess Homocysteine Levels?

Homocysteine is an amino acid containing sulfur that is not used for protein synthesis. It is formed during the methionine cycle, also known as the transsulfuration methylation cycle, which plays a crucial role in linking sulfur amino acid metabolism with important methylation reactions. Homocysteine can be produced by breaking down S-adenosylmethionine or by converting homocysteine thiolactone, a toxic substance, to homocysteine using paraoxonase 1 (PON1), an enzyme that also helps detoxify organophosphate pesticides.

To clear homocysteine from the body, methyltetrahydrofolate, methylcobalamin, betaine, or pyridoxal-5-phosphate is needed. Methylcobalamin is a highly effective methylating coenzyme that can directly convert homocysteine to methionine without the need for another enzyme.

Various factors can increase homocysteine levels, including genetic deficiencies in enzymes involved in the transsulfuration methylation cycle (such as MTHFR, CBS, BHMT, and others), a diet high in methionine, or deficiencies in folate, vitamin B12, vitamin B6, or betaine. Megadoses of niacin, nitrous oxide anesthesia, and excessive copper can also lead to elevated homocysteine levels.

On the other hand, a diet rich in folate compounds, vitamin B12, methylcobalamin, betaine, or supplements containing these nutrients can help lower homocysteine levels. Exposure to certain toxic chemicals can activate CBS, leading to increased conversion of homocysteine to cystathionine and a decrease in homocysteine levels. Removing toxic substances from the body may also result in increased serum homocysteine levels.

What are Testing Considerations?

An excess of cystathionine beta-synthase can significantly affect homocysteine levels and make it an unreliable marker of the transsulfuration methylation cycle. This is commonly seen in individuals with Down’s syndrome, where the CBS enzyme is overproduced due to the presence of an additional copy of chromosome 21. This leads to a reduction in homocysteine levels as the excess CBS channels homocysteine into the CBS reaction, limiting methionine production. In such cases, it is crucial to increase coenzymes like methyltetrahydrofolate, methylcobalamin, and the methyl donor betaine.

Exposure to toxic chemicals can also lead to an increase in CBS production, allowing the body to produce more glutathione to detoxify the toxins. This can result in low homocysteine values, rather than high values. Low homocysteine levels in autism may be associated with severe toxic chemical exposure, confirmed in many cases of autism. In such cases, the baseline homocysteine may be below 7.0, and serum homocysteine may increase after detoxification.

Organic acids testing can be helpful in such cases. The markers for excessive CBS activity (2-hydroxybutyric acid), toxicity (succinic acid), and glutathione deficiency (elevated pyroglutamic acid) can be used to determine the transsulfuration methylation pathway. 2-Hydroxybutyric acid is a downstream product of CBS activity and is usually high in Down’s syndrome and toxic exposure cases, while plasma homocysteine is low. Succinic acid is often high due to toxic inhibitory effects on succinic acid dehydrogenase in the Krebs cycle, and the glutathione deficiency marker pyroglutamic acid will be high in cases of toxicity.

Learn More About the Homocysteine Test: Explore FAQs


This test will allow you to personalize patient care through determination of homocysteine levels.

  • Homocysteine

Sample Reports

The Homocysteine Test report can help to determine if intervention is needed to prevent the toxic effects of excess homocysteine.

Test Prep and Instructions

MosaicDX offers patient-friendly sample collection kits that simplify testing. Our kits include visual, step-by-step instructions for test preparation and sample collection, personalized shipping cards, and pediatric collection bags if needed. With MosaicDX, patients can easily collect samples for testing with confidence and accuracy.

Frequently Asked Questions

The ordering process for MosaicDX tests starts with your healthcare practitioner assessing your symptoms and recommending the most appropriate test.

Once a test has been recommended, collection kits can be conveniently ordered and delivered straight to your doorstep. If you already have a collection kit, you can register your test and begin the process at your convenience.

It is important to carefully follow the collection instructions and include all required information about yourself and your specimens when registering your test. When your specimens are collected, you can use the prepaid shipping materials provided in your kit to ship them to MosaicDX. Your results will be accessible online via the MosaicDX portal. We recommend scheduling an appointment with your healthcare practitioner to discuss your results and develop a plan for your healthcare

If you are located outside of the U.S., our customer service team can assist you in finding a distributor in your country. In countries where a distributor is not required, you can place an order through our international patient ordering site. Please note that all international shipping costs must be paid prior to shipping the kit.  

Individuals with high levels of homocysteine in their blood have been found to have an increased risk of hip fracture, particularly among men. The risk for hip fracture was almost four times higher in men and 1.9 times higher in women in the highest quartile of serum homocysteine levels compared to those in the lowest quartile. One potential explanation for this association is that homocysteine may disrupt the formation of cross-links in collagen, which could contribute to the development of osteoporosis. Interestingly, this relationship between homocysteine levels and fracture risk appeared to be independent of other factors that are known to contribute to fracture risk, including bone mineral density.

A study of 521 subjects over the age of 65 who were not depressed at the beginning, found that low levels of folate and vitamin B12 and high levels of homocysteine were associated with a higher risk of developing depression during a follow-up period of two to three years. There are various ways in which elevated homocysteine may be linked to the underlying biological causes of psychiatric disorders. Homocysteine has been shown to interact with NMDA receptors, cause oxidative stress, induce apoptosis, lead to mitochondrial dysfunction, and cause vascular damage. Elevated levels of homocysteine may also contribute to cognitive impairment, which is often observed in patients with affective disorders and schizophrenia. Supplementation with B vitamins and folic acid has been demonstrated to be effective in reducing homocysteine levels. The addition of L-methylfolate, in doses ranging from 7.5 to 15 mg per day, to antidepressant therapy at the beginning of treatment was found to be more effective than antidepressant therapy alone in alleviating depressive symptoms. Moreover, clinical depression evaluation scores indicated major symptom improvement within 60 days of adding L-methylfolate to antidepressant therapy, and it was better tolerated than SSRI/SNRI monotherapy.

When there is a deficiency of folate, uracil replaces thymine in DNA, which may lead to DNA strand breaks and hypomethylation within the hepatic p53 tumor suppressor gene, thereby increasing the risk of cancer. Studies have revealed that patients suffering from ovarian, pancreatic, colorectal, head and neck squamous cell carcinomas, and acute lymphoblastic leukemia have higher levels of homocysteine. Moreover, rapid proliferating tumor cell lines exhibited an increase in homocysteine levels, whereas plasma homocysteine levels declined when tumor cells began to die.

Different states have regulations that define the scope of practice for practitioners. It is the practitioner’s responsibility to abide by these rules. Check with your state board of health to determine any restrictions related to laboratory testing. Please note, Mosaic Diagnostics does not offer testing in New York. 

Once you have opened your account, you have the options of ordering kits to stock in your office or drop-ship kits directly to your patients through your MosaicDX portal.   

Watch our short tutorial videos on how to conveniently  

Already have a kit? Watch this video on how to place an order for your patient using a kit from your inventory.   

Please refer to your test’s specific Test Preparation and Instructions for more information regarding the potential effects of medications, foods, and supplements on this test. 

You make also consult your healthcare provider prior to making any changes to your medications.

Visit the payment information page for an overview of payment options and procedures along with insurance coverage overview.

NOTE: Insurance coverage for testing is based on several factors such as the type of procedure, diagnosis, and insurance policy guidelines. Patients are encouraged to contact their insurance company to check for coverage and to provide the procedure codes (CPT codes) and diagnostic codes (ICD-10 codes). The CPT codes can be found on the billing information page, while ICD-10 codes are provided by the practitioner.

Mosaic Diagnostics offers written interpretations within test reports and complimentary consultations with our clinical educators for qualified practitioners. To schedule a consultation, simply sign in to your MosaicDX account and book a consultation online. 

We encourage all patients to discuss results with your practitioner.

Our Resources tab also contains educational materials that you may find useful, we also offer MosaicEDGE workshops for qualified practitioners to better understand the fundamentals of lab testing.

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Clinical References