Sorted By Test Name - Mayo Medical Laboratories

B6PA
61065
P5NT
80650
PDHC
83899
-If PLP is >100 mcg/L and PA is 31 to 100 mcg/L; or PLP is 81 to 100 mcg/L and PA is < or =30 mcg/L,
the increased pyridoxal 5-phosphate is likely related to dietary supplementation; however a mild
expression of hypophosphatasia cannot be excluded. Consider analysis of serum alkaline phosphatase
isoenzymes (ALKI/89503 Alkaline Phosphatase, Total and Isoenzymes, Serum) and urinary
phosphoethanolamine (AAPD/60475, Amino Acids, Quantitative, Random, Urine). -If PLP is 51 to 80
mcg/L or PLP is 81 to 100 mcg/L and PA is >30; or PLP is >100 mcg/L and PA is >100 mcg/L, the
elevated pyridoxal 5-phosphate is likely due to dietary supplementation.
Reference Values:
5-50 mcg/L
Clinical References: 1. Kimura M, Kanehira K, Yokoi K: Highly sensitive and simple liquid
chromatographic determination in plasma of B6 vitamins, especially pyridoxal 5'-phosphate. J
Chromatogr A 1996;722(1-2):296-301 2. Ball GFM: Vitamins: Their Role in the Human Body. Blackwell
Publishing. Oxford, 2004, pp 310-325 3. Mackey AD, Davis SR, Gregory JF III: Vitamin B6. In Modern
Nutrition in Health and Disease. Tenth edition. Edited by ME Shils, M Shike, AC Ross, et al.
Philadelphia, Lippincott Williams and Wilkins, 2006, pp 452-461
Pyridoxic Acid (PA), Plasma
Reference Values:
Only orderable as part of a profile. For further information see #61064 Vitamin B6 Profile (PLP and PA),
P.
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
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