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HelpTest Code SUAC Succinylacetone, Blood Spot
Reporting Name
Succinylacetone, BSUseful For
Second-tier newborn screen for tyrosinemia type 1 (HT-1) when primary screen showed nonspecific elevations of tyrosine
Diagnosing HT-1 when used in conjunction with testing for urine organic acids, liver function, alpha-fetoprotein, and molecular genetic analysis of FAH
Method Name
Liquid Chromatography Tandem Mass Spectrometry (LC-MS/MS)
Performing Laboratory
Mayo Clinic Laboratories in Rochester
Specimen Type
Whole bloodOrdering Guidance
The preferred test for diagnosis and monitoring of patients with tyrosinemia type 1 is TYRBS / Tyrosinemia Follow Up Panel, Blood Spot.
Necessary Information
Specimen Required
Submit only 1 of the following specimen types:
Preferred:
Specimen Type: Blood Spot
Supplies: Card - Blood Spot Collection (Filter Paper) (T493)
Container/Tube:
Preferred: Blood Spot Collection Card
Acceptable: Whatman Protein Saver 903 Paper, PerkinElmer 226 filter paper, Munktell filter paper, or blood collected in tube containing EDTA and dried on filter paper.
Specimen Volume: 2 blood spots
Collection Instructions:
1. At least 1 spot should be complete (ie, unpunched).
2. Do not expose specimen to heat or direct sunlight.
3. Do not stack wet specimens.
4. Keep specimen dry.
5. If collection of a new specimen is necessary, let blood dry on the Blood Spot Collection Card (T493) at ambient temperature in a horizontal position for a minimum of 3 hours.
Specimen Stability Information: Ambient (preferred) 7 days/Refrigerated 14 days/Frozen 90 days
Additional Information:
1. For collection instructions, see Blood Spot Collection Instructions
2. For collection instructions in Spanish, see Blood Spot Collection Card-Spanish Instructions (T777)
3. For collection instructions in Chinese, see Blood Spot Collection Card-Chinese Instructions (T800)
Acceptable
Specimen Type: Whole Blood
Container/Tube: Lavender top (EDTA)
Specimen Volume: 2 mL
Collection Instructions: Send whole blood specimen in original tube. Do not aliquot.
Specimen Stability Information: Refrigerate 6 days
Specimen Minimum Volume
Blood Spot: 1
Whole Blood: 0.5 mL
Specimen Stability Information
| Specimen Type | Temperature | Time | Special Container |
|---|---|---|---|
| Whole blood | Varies | ||
Reject Due To
| Blood spot specimen that shows serum rings or has multiple layers | Reject |
| Insufficient specimen | Reject |
| Unapproved filter papers | Reject |
Special Instructions
Reference Values
SUCCINYLACETONE
≤1.0 nmol/mL
TYROSINE
<4 weeks: 40-280 nmol/mL
≥4 weeks: 25-150 nmol/mL
Day(s) Performed
Monday through Friday
CPT Code Information
84510
82542
82542 (if appropriate for government payers)
LOINC Code Information
| Test ID | Test Order Name | Order LOINC Value |
|---|---|---|
| SUAC | Succinylacetone, BS | 53231-7 |
| Result ID | Test Result Name | Result LOINC Value |
|---|---|---|
| 22714 | Interpretation | 59462-2 |
| 607629 | Succinylacetone | 53231-7 |
| 607630 | Tyrosine | 35571-9 |
| 22716 | Reviewed By | 18771-6 |
Clinical Information
Tyrosinemia type 1 (hepatorenal tyrosinemia, HT-1) is an autosomal recessive condition caused by a deficiency of the enzyme fumarylacetoacetate hydrolase (FAH). HT-1 primarily affects the liver, kidneys, and peripheral nerves, causing severe liver disease, renal tubular dysfunction, and neurologic crises. If left untreated, most patients die of liver failure in the first years of life and all are at risk of developing hepatocellular carcinoma. Treatment with 2-(2-nitro-4-trifluoromethylbenzoyl)-1,3 cyclohexanedione (NTBC) is available and is particularly effective when initiated in newborns. The incidence of HT-1 is approximately 1 in 100,000 live births.
While tyrosine can be determined by routine newborn screening, it is not a specific marker for tyrosinemia type I and often may be associated with common and benign transient tyrosinemia of the newborn. Succinylacetone is a specific marker for HT-1 but not consistently measured by newborn screening programs. This assay determines succinylacetone and tyrosine in newborn blood spots by tandem mass spectrometry. Additional follow-up testing may include confirmatory molecular analysis of the FAH gene.
Interpretation
Elevations of succinylacetone (SUAC) above the reference range with or without elevations of tyrosine (TYR) are indicative of tyrosinemia type 1.
Elevations of TYR above the reference range without elevations of SUAC may be suggestive of tyrosinemia type II, type III, transient hypertyrosinemia of the neonate, or nonspecific liver disease.
Cautions
Normal levels may be seen in affected individuals undergoing treatment.
In rare cases of tyrosinemia type 1, tyrosine or succinylacetone may not be elevated.(1)
Method Description
A 3-mm disk is punched out of the dried blood spot onto a 96-well plate. The amino acids are extracted by the addition of acetonitrile and a known concentration of isotopically labeled amino acids as internal standards. The extract is moved to another 96-well plate, dried under a stream of nitrogen, and derivatized by the addition of n-butanol hydrochloric acid. Analytes are measured by liquid chromatography tandem mass spectrometry. The concentrations of the analytes are established by computerized comparison of ion intensities of these analytes to that of the respective internal standards.(Unpublished Mayo method)
Report Available
3 to 5 daysTest Classification
This test was developed and its performance characteristics determined by Mayo Clinic in a manner consistent with CLIA requirements. It has not been cleared or approved by the US Food and Drug Administration.Genetics Test Information
This test is a second-tier newborn screen for tyrosinemia type 1.