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Test ID: TYRBS Tyrosinemia Follow Up Panel, Blood Spot

Necessary Information

Patient's age and reason for testing are required.

Specimen Required

Submit only 1 of the following specimen types:



Specimen Type: Blood spot

Supplies: Card-Blood Spot Collection (Filter Paper) (T493)


Preferred: Blood Spot Collection Card

Acceptable: Whatman Protein Saver 903 Paper, PerkinElmer 226 (formerly Ahlstrom 226) filter paper, Munktell filter paper, or blood collected in tubes containing heparin, ACD or EDTA and dried on filter paper

Specimen Volume: 2 Blood spots

Collection Instructions:

1. An alternative blood collection option for a patient older than 1 year of age is a fingerstick. See Dried Blood Spot Collection Tutorial for how to collect blood spots via fingerstick.

2. At least 2 spots should be complete (ie, unpunched).

3. Let blood dry on filter paper at room temperature in a horizontal position for a minimum of 3 hours.

4. Do not expose specimen to heat or direct sunlight.

5. . Do not stack wet specimens.

6. Keep specimen dry.

Specimen Stability Information: Ambient (preferred) 90 days/Refrigerated 90days/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)



Specimen Type: Whole blood


Preferred: Lavender top (EDTA)

Acceptable: Green top (sodium or lithium heparin) and yellow top (ACD)

Specimen Volume: 2 mL

Collection Instructions: Send whole blood specimen in original tube. Do not aliquot.

Specimen Stability Information: Refrigerate (preferred) 4 days/Ambient 4 days

Useful For

Monitoring of individuals with tyrosinemia type I (HT-1)


Diagnosis of HT-1 when used in conjunction with testing for urine organic acids ,liver function, alpha-fetoprotein, and molecular genetic analysis of the fumarylacetoacetate hydrolase (FAH) gene

Method Name

Liquid Chromatography-Tandem Mass Spectrometry (LC-MS/MS)

Reporting Name

Tyrosinemia Follow Up Panel, BS

Specimen Type

Whole blood

Specimen Minimum Volume

Blood Spots: 1
Whole Blood: 0.5 mL

Specimen Stability Information

Specimen Type Temperature Time Special Container
Whole blood Varies

Clinical Information

Tyrosinemia type 1 (hepatorenal tyrosinemia, HT-1) is an autosomal recessive condition caused by a deficiency of the enzyme fumarylacetoacetate hydrolase . 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 (HCC). The incidence of HT-1 is approximately 1 in 100,000 live births.


Affected individuals can show a partial response to dietary restriction of phenylalanine and tyrosine, but dietary treatment in conjunction with the administration of 2-(2-nitro-4-trifluoromethylbenzoyl)-1,3 cyclohexanedione (NTBC; nitisinone), an inhibitor of the proximal tyrosinemia pathway, is very effective when initiated in newborns. Outcome data are promising, and to date, newborn patients treated with NTBC have not developed acute liver disease, neurologic crises, or HCC.


According to treatment guidelines established in 2017, monitoring of blood NTBC concentration and succinylacetone (SUAC) levels along with measuring the dietary intake of amino acids, including tyrosine and phenylalanine are part of an individualized surveillance plan for patients with HT-1.(1) Monthly analysis of SUAC, NTBC concentration, and amino acids is suggested for the first year of life with the same compounds being monitored every 3 months to age 5 years and every 6 months thereafter.


The analytes encompassed in this assay satisfy the recommendations for diagnosis and monitoring of HT-1. In particular, for NTBC, the current guidelines recommend 40 nmol/mL to 60 nmol/mL plasma concentration, which corresponds to a target range for NTBC in dried blood spots of 17 nmol/mL to 26 nmol/mL based on a blood to plasma conversion factor of 2.34.(2) Data from the validation of this assay suggests that NTBC dosing could be individualized while not to exceed DBS levels of 26 nmol/mL.(3)

Reference Values


<4 weeks 40.0-280.0 nmol/mL

≥4 weeks 25.0-150.0 nmol/mL



27.0-107.0 nmol/mL



11.0-45.0 nmol/mL



<1.00 nmol/mL



<0.7 nmol/mL


Quantitative results with reference values are reported without added interpretation. When applicable, reports of abnormal results may contain an interpretation based on available clinical information.

Clinical Reference

1. Chinsky JM, Singh R, Ficiciolglu C, et. al: Diagnosis and treatment of tyrosinemia type I: a US and Canadian consensus group review and recommendations. Genet Med. 2017 Dec;19(12). doi: 10.1038/gim.2017.101

2. Laeremans H, Turner C, Andersson T, et al: Inter-laboratory analytical improvement of succinylacetone and nitisinone quantification from dried blood spot samples. JIMD Rep. 2020 May;53(1):90-102

3. Schultz MJ, Netzel BC, Singh RH, et al: Laboratory monitoring of patients with hereditary tyrosinemia type I. Mol Genet Metab. 2020 Aug;130(4):247-254

4. Mitchell GA, Grompe M, Lambert M, Tanguay RM: Hypertyrosinemia. In: Valle D, Beaudet AL, Vogelstein B, et al, eds. The Online Metabolic and Molecular Bases of Inherited Disease. McGraw-Hill; 2019. Accessed January 06, 2022. Available at

5. Blackburn PR, Hickey RD, Nace RA, et al: Silent tyrosinemia type I without elevated tyrosine or succinylacetone associated with liver cirrhosis and hepatocellular carcinoma. Hum Mutat. 2016 Oct;37(10):1097-1105. doi: 10.1002/humu.23047

Day(s) Performed

Monday through Friday

Report Available

3 to 5 days

Test Classification

This test was developed, and its performance characteristics determined by Mayo Clinic in a manner consistent with CLIA requirements. This test has not been cleared or approved by the US Food and Drug Administration.

CPT Code Information






82542 only (if appropriate for government payers)

LOINC Code Information

Test ID Test Order Name Order LOINC Value
TYRBS Tyrosinemia Follow Up Panel, BS 94573-3


Result ID Test Result Name Result LOINC Value
607553 Tyrosine 35571-9
607554 Phenylalanine 29573-3
607555 Methionine 47700-0
607556 Succinylacetone 53231-7
607557 Nitisinone 85098-2
BG722 Reason for Referral 42349-1
607552 Reviewed By 18771-6
Mayo Clinic Laboratories | Genetics and Pharmacogenomics Catalog Additional Information: