Mayo Test Catalog, (Sorted By Test Name) - Mayo Medical ...

P5NT
80650
PDHC
83899
Pyrimidine 5' Nucleotidase, Blood
Clinical Information: Pyrimidine 5' nucleotidase (P5'NT) is involved in the catabolism of RNA
which is a normal constituent of reticulocytes but not of mature erythrocytes. A deficiency of P5'NT is
evidenced by persistent reticulocytosis.
Useful For: Workup of individuals with persistent reticulocytosis
Interpretation: Screening test negative for pyrimidine 5'nucleotidase deficiency
Reference Values:
Normal
Clinical References: Fairbanks VF, Klee GG: Biochemical aspects of hematology. In Tietz
Textbook of Clinical Chemistry. 3rd Edition. Edited by CA Burtis, ER Ashwood, Philadelphia, WB
Saunders Co., 1999, pp 1642-1647
Pyruvate Dehydrogenase Complex (PDHC), Fibroblasts
Clinical Information: The pyruvate dehydrogenase complex (PDHC) catalyzes the oxidative
decarboxylation of pyruvate to acetyl-CoA, which is an entry point for the tricarboxylic acid (TCA)
cycle and a critical step in the production of cellular energy. PDHC is a multienzyme complex located
in the inner mitochondrial membrane, consisting of 6 different components: pyruvate decarboxylase
(E1, with alpha and beta subunits), dihydrolipoic transacetylase (E2), dihydrolipoyl dehydrogenase
(E3), 2 regulatory enzymes (PDH kinase and PDH phosphatase), and E3-binding protein. PDHC
deficiency is a mitochondrial disorder with a variable clinical presentation ranging from fatal congenital
lactic acidosis to relatively mild ataxia or neuropathy. In infants and children with PDHC deficiency,
the most common features are delayed development and hypotonia. Seizures and ataxia are also
frequent features. Less common manifestations include congenital brain malformations, particularly
agenesis of the corpus callosum, or degenerative changes, including Leigh disease. Facial dysmorphism
can be seen as well. The severity of the disease progression is thought to be related to the severity of the
lactic acidosis. PDHC deficiency can be caused by defects in the E1 alpha, E1 beta, E2, or E3 subunits.
The most common cause of PDHC deficiency is a defect in the E1 alpha gene, located on the X
chromosome. It is considered an X-linked dominant condition in that both females and males with an
E1 alpha gene mutation are affected with PDHC deficiency. Mutations in the E1 alpha gene are
typically de novo. The most important initial diagnostic test is the measurement of blood and
cerebrospinal fluid lactate and pyruvate, along with a lactate-to-pyruvate (L:P) ratio (typically normal
ratio with elevated lactate and pyruvate). Additionally, plasma amino acids (AAQP/9265 Amino Acids,
Quantitative, Plasma) may detect an increase in alanine. A diagnosis of PDHC deficiency depends on
the measurement of enzyme activity in cells or tissues, most commonly in skin fibroblasts.
Useful For: Evaluation of patients with a clinical suspicion of a pyruvate dehydrogenase complex
deficiency or an energy metabolism disorder
Interpretation: When below-normal enzyme activities are detected, a detailed interpretation is
given. This interpretation includes an overview of the results and their significance, a correlation to
available clinical information, elements of differential diagnosis, and recommendations for additional
biochemical testing.
Reference Values:
PDHC, ACTIVATED
Range: 1.63-3.61 mU/mg protein
PDHC, INACTIVATED
Range: 0.18-2.18 mU/mg protein
Reference values apply to all ages.
Clinical References: 1. Patel KP, Obrien TW, Subramony SH, et al: The spectrum of pyruvate
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