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Test Catalog

Test ID: TALDO    
Polyols, Quantitative, Urine

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Useful For Suggests clinical disorders or settings where the test may be helpful

Diagnosis of transaldolase (TALDO) deficiency or ribose-5-phosphate isomerase (RPI) deficiency

Genetics Test Information Provides information that may help with selection of the correct test or proper submission of the test request

Screening for transaldolase deficiency (TALDO) or ribose-5-phosphate isomerase (RPI) deficiency.

Clinical Information Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test

Polyols are sugar alcohols that have been identified in blood, urine, and cerebrospinal fluid. Characteristic patterns of abnormal polyols may suggest a disorder of the pentose phosphate pathway (PPP) including transaldolase (TALDO) deficiency and ribose-5-phosphate isomerase (RPI) deficiency. The PPP is involved in carbohydrate metabolism and is present in the cytosol of all cells. Two specific functions of the PPP are the production of nicotinamide adenine dinucleotide phosphate (NADPH) and the synthesis of ribose-5-phosphate, a molecule necessary for nucleotide and nucleic acid synthesis. Both TALDO and RPI deficiency that have multisystem involvement are recently described disorders of this pathway.


TALDO deficiency is an autosomal recessive disorder caused by a reduction of the enzyme transaldolase.(1) Clinical manifestations are characterized by severe neonatal liver failure, coagulopathy, low serum protein, hypoglycemia, high ammonia, progressive myocardial hypertrophy, and abnormal lactate dehydrogenase with remarkably normal or low transaminases.


Patients may present in the antenatal period with HELLP syndrome (hemolysis, elevated liver enzymes, low platelets) of the mother, hydrops fetalis and oligohydramnios, dysmorphic features, cutis laxa, and hypertrichosis. The clinical course is variable, but acute liver failure with normal transaminases is a common finding. Initially, hepatomegaly is absent, but the spleen may be enlarged. Later, hepatomegaly with liver cirrhosis and mild kidney failure occur.


RPI deficiency is an autosomal recessive disorder caused by a deficiency of the enzyme ribose-5-phosphate isomerase.(2) Clinical manifestations include neurological deficits such as slow progressing leukoencephalopathy and neuropathy. Additionally, spasticity, ataxia, epilepsy, regression, and delayed psychomotor development have been described.


Polyols analysis in urine is the method of choice for the biochemical diagnosis of TALDO and RPI deficiency. For evaluation for familial inheritance, TALDO can be confirmed by enzyme analysis in erythrocytes and lymphoblasts, and by mutation analysis of the TALDO1 gene. RPI deficiency can be confirmed with molecular analysis and currently, there is a single lab in the United States that offers next-generation sequencing of RPIA.

Reference Values Describes reference intervals and additional information for interpretation of test results. May include intervals based on age and sex when appropriate. Intervals are Mayo-derived, unless otherwise designated. If an interpretive report is provided, the reference value field will state this.


0-11 months

1-3 years

4-17 years

> or =18 years






















Values are expressed in mmol/mol creatinine

Interpretation Provides information to assist in interpretation of the test results

An interpretive report is provided.


All profiles are reviewed by the laboratory director and interpretation is based on pattern recognition. A detailed interpretation is given, including an overview of the results and of their significance, a correlation to available clinical information, elements of differential diagnosis, recommendations for additional biochemical testing and in vitro confirmatory studies (enzyme assay, molecular analysis), name and phone number of key contacts who may provide these studies at Mayo or elsewhere, and a phone number to reach one of the laboratory directors in case the referring physician has additional questions.

Cautions Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances

A positive test result is diagnostic of transaldolase (TALDO) deficiency or ribose-5-phosphate isomerase (RPI) deficiency; however it is strongly recommended to follow-up with molecular analysis.

Clinical Reference Provides recommendations for further in-depth reading of a clinical nature

1. Online Mendelian Inheritance in Man. 606003. National Center for Biotechnology Information. Available at

2. Online Mendelian Inheritance in Man. 608611. National Center for Biotechnology Information. Available at

3. Eyaid W, Al Harbi T, Anazi S, et al: Transaldolase deficiency: report of 12 new cases and further delineation of the phenotype. Journal of Inherited Metabolic Disease (2013).36:997-1004

4. Huck JHJ, Verhoeven NM, Struys EA, et al: Ribose-5-phosphate isomerase deficiency: New inborn error in the pentose phosphate pathway associated with a slowly progressive leukoencephalopathy. American Journal of Human Genetics (2004)74:745-751

5. Wamelink MMC, Struys EA, Jakobs C: The biochemistry, metabolism and inherited defects of the pentose phosphate pathway: A review. Journal of Inherited Metabolic Disease (2008)31:703-717

Special Instructions and Forms Describes specimen collection and preparation information, test algorithms, and other information pertinent to test. Also includes pertinent information and consent forms to be used when requesting a particular test