Understanding Your Laboratory Test: A Patient's Guide to Medical Testing
This test measures the activity of the enzyme adenosyl homocysteine hydrolase (AHCY) in red blood cells to help diagnose certain metabolic disorders.
{"Measures AHCY enzyme activity in red blood cells","Helps diagnose homocysteine metabolism disorders","Involves a simple blood draw","Results aid in identifying genetic metabolic conditions","Abnormal results may require further genetic testing"}
Key facts at a glance
- LOINC
- 47827-1
- Short code
- AHCY RBC
- Synonyms
- Adenosyl homocysteine hydrolase RBC-cCnt
- Category
- chemistry
- Sample
- whole-blood
- Container
- Lavender top (EDTA) tube
- Units
- N/A
- Ref low
- 4.2
- Ref high
- 5.9
- Critical range
- 2 N/A – 7 N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- Method
- Enzymatic assay (spectrophotometric or HPLC-based)
- CPT
- 82657
- SNOMED
- 313295004
- Specimen volume
- 2-3 mL whole blood
- Stability
- Process within 24 hours; store at 2-8°C if delay exceeds 2 hours. Avoid freezing whole blood. Separate RBCs from plasma within 2 hours of collection.
- Hemolysis max
- 50
- Lipemia max
- 300
- Icterus max
- 20
- TAT
- 72–168 hours
- Order
- routine
What is this test, and what is it used to check or measure in my body?
The Adenosyl Homocysteine Hydrolase (AHCY) test measures how well this enzyme works in your red blood cells. AHCY is an important enzyme that helps break down a substance called S-adenosylhomocysteine (SAH) into adenosine and homocysteine. This process is essential for proper cell function and for keeping homocysteine levels balanced in your body.
Why is this test performed, and what health conditions can it help detect or rule out?
This test is primarily used to help diagnose rare genetic disorders that affect homocysteine metabolism, particularly AHCY deficiency. It may also be used to investigate unexplained elevated homocysteine levels (hyperhomocysteinemia) or related neurological symptoms. The test helps doctors understand if a problem with this specific enzyme is causing health issues.
How is this test done, and what should I expect before, during, and after the procedure?
A healthcare professional will draw a small sample of blood from a vein in your arm using a needle. The blood is collected in a tube and sent to a laboratory for analysis. The sample is processed to isolate the red blood cells, and the AHCY enzyme activity is measured. No special preparation (like fasting) is typically required, but follow your doctor's instructions.
What do the results of this test mean, and how will my doctor use them to guide my care?
Low or absent AHCY enzyme activity in red blood cells may indicate AHCY deficiency, a rare genetic disorder that affects how your body processes homocysteine. This can lead to accumulation of toxic substances and various health problems. Your doctor will interpret your results in combination with your symptoms, medical history, and other test results to make an accurate diagnosis.
Reference range
Adult males: 4.2-5.9; Females: 3.8-5.1 x 10^12/LN/A
No special preparation required. Patient does not need to fast prior to sample collection. Inform the laboratory of any recent blood transfusions, as this may affect results.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
The AHCY test is clinically significant for diagnosing rare inborn errors of metabolism, particularly AHCY deficiency (also known as S-adenosylhomocysteine hydrolase deficiency). This condition is inherited and affects the body's ability to properly metabolize homocysteine, leading to accumulation of toxic metabolites. Clinical manifestations may include neurological symptoms, developmental delays, muscle weakness, and elevated homocysteine levels in blood and urine. Early diagnosis through this test can guide appropriate management and treatment strategies.
Frequently asked questions
Is fasting required before this test?
Are there any risks with the blood draw?
How long does it take to get results?
What happens if my results are abnormal?
Is this test used for routine health checkups?
Sources
- 1
- 2
- 3
Click any link to access the full source. PubMed Central (PMC) links provide free full-text access.
This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.
This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.
If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.
Medically reviewed by WellAlly Editorial Team Last reviewed August 17, 2026. · Read our editorial policy