Bckaddbsql

Published: August 9, 2026Updated: August 17, 2026

This test checks for a rare genetic metabolic disorder called Maple Syrup Urine Disease (MSUD) by measuring the activity of the branched chain keto-acid dehydrogenase enzyme.

Quick summary

{"Screens for Maple Syrup Urine Disease (MSUD), a rare inherited metabolic disorder","Tests the enzyme that breaks down certain amino acids (leucine, isoleucine, valine)","Usually performed on newborns as part of routine newborn screening","Early detection allows for early treatment and better outcomes","Treatment involves a special diet to limit harmful amino acid buildup"}

Medically reviewed by WellAlly Editorial TeamLast reviewed August 17, 2026Editorial policy

Key facts at a glance

LOINC: 38479-2
Short code: BCKDH-DBS
Synonyms: BCKAD DBS Ql
Category: chemistry
Sample: serum
Container: Dried Blood Spot (DBS) collection card - Whatman 903 filter paper or equivalent FDA-approved newborn screening collection card; ensure proper saturation of all circles
Units: N/A
Ref low: 22
Ref high: 198
Critical range: — – 10000 N/A
Fasting: false
Population: adult
Sex: all
Age range: 0–120 years
Method: Enzyme activity assay via radiometric or fluorometric detection of decarboxylation products; confirmatory methods include molecular genetic analysis of BCKDHA, BCKDHB, DBT, and DLD genes
CPT: 82017
SNOMED: 398311002
Specimen volume: Minimum 2-3 fully saturated DBS circles; approximately 75-100 microliters of whole blood per spot. Avoid touching or smearing the blood spots
Stability: DBS specimens stable at room temperature (15-25°C) for up to 7 days; refrigerated (2-8°C) for up to 30 days; frozen (-20°C or lower) for up to 1 year. Avoid humidity and direct sunlight exposure
Hemolysis max: 500
Lipemia max: 1000
Icterus max: 500
TAT: 24–168 hours
Order: routine

What is this test?

The branched chain keto-acid dehydrogenase (BCKDH) complex test is a blood test that measures whether the enzyme needed to break down certain amino acids is working properly. This enzyme helps the body process three essential amino acids found in protein: leucine, isoleucine, and valine.

Why is it important?

When this enzyme is missing or not working correctly, these amino acids and their toxic byproducts build up in the body. This causes a condition called Maple Syrup Urine Disease (MSUD), named because the urine has a sweet, maple syrup-like odor. Without treatment, MSUD can lead to serious health problems including developmental delays, seizures, coma, and can be life-threatening.

How is the test done?

A small blood sample is taken from your baby, usually by a heel stick. The blood is then sent to a laboratory to check the activity level of the BCKDH enzyme. This test is often part of routine newborn screening programs performed within the first few days of life.

Reference range

Adult males: 22-198 U/L; Females: 22-198 U/LN/A

Specimen: serum

No special preparation required. For newborn screening, dried blood spot (DBS) specimen should be collected between 24-72 hours of life per standard newborn screening protocols. Repeat testing may be required if initial sample collected before 24 hours

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings2

Frequently asked questions

Is this test painful for my baby?

The test requires a small blood sample, typically from a heel stick. This may cause brief discomfort or crying, but it is generally well-tolerated and over quickly. The benefits of early detection far outweigh the momentary discomfort.

What if the test results are abnormal?

An abnormal result does not always mean your baby has MSUD. It indicates the need for further testing to confirm the diagnosis. If MSUD is confirmed, treatment can begin immediately, which is crucial for preventing complications. Your healthcare team will guide you through the next steps.

Can MSUD be treated?

Yes, MSUD can be managed effectively with a special low-protein diet that limits the intake of leucine, isoleucine, and valine. This typically involves special medical formulas and carefully measured amounts of natural protein. With early and continuous treatment, individuals with MSUD can lead healthy, productive lives.

Is MSUD inherited?

Yes, MSUD is an inherited genetic disorder. Both parents must carry a mutated gene for their child to develop the condition. Parents who have had a child with MSUD have a 25% chance of having another child with the disease. Genetic counseling is recommended for families with a history of MSUD.

Sources

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.

Medical Disclaimer

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