Sorted By Test Name - Mayo Medical Laboratories

ALLOI
88888
> or =19 years: 0.0-20.6%
Intestine
0-6 years: 0.0-37.7 IU/L
7-9 years: 0.0-45.6 IU/L
10-13 years: 0.0-40.0 IU/L
14-15 years: 0.0-26.4 IU/L
16-18 years: 0.0-12.7 IU/L
> or =19 years: 0.0-11.0 IU/L
Placental
Not present
Clinical References: 1. Tietz Textbook of Clinical Chemistry, Edited by CA Burtis, ER Ashwood.
Philadelphia, WB Saunders Company, 1999 2. Moss DW: Alkaline phosphatase isoenzymes. Clin Chem
1982;28:2007-2016
Allo-isoleucine, Blood Spot
Clinical Information: Maple-syrup urine disease (MSUD) is an autosomal recessive deficiency of
the branched-chain-ketoacid dehydrogenase (BCKDH) complex. The BCKDH complex is involved in the
metabolism of the branched-chain amino acids (BCAA): isoleucine (Ile), leucine (Leu), and valine (Val).
Classic MSUD presents in the neonate with feeding intolerance, failure to thrive, vomiting, lethargy, and
maple-syrup odor to urine and cerumen. If untreated, it progresses to irreversible mental retardation,
hyperactivity, failure to thrive, seizures, coma, cerebral edema, and possibly death. MSUD is a panethnic
condition, but is most prevalent in the Old Order Mennonite community in Lancaster, Pennsylvania. The
incidence of MSUD is approximately 1:200,000 live births in the general population and 1:760 live births
among the Old Order Mennonites. Newborn screening includes the measurement of BCAA (Leu, Ile, and
Val), which are elevated in MSUD. However, unaffected infants receiving total parenteral nutrition
frequently have increased levels of BCAA, a situation that often triggers unnecessary follow-up
investigations. Abnormal concentrations of allo-isoleucine (Allo-Ile) are pathognomonic for MSUD. The
determination of Allo-Ile (second-tier testing) in the same newborn screening specimens that reveals
elevated BCAA allows for positive identification of patients with MSUD and differentiation from BCAA
elevations due to dietary artefacts, reducing the occurrence of false-positive newborn screening results.
Treatment of MSUD aims to normalize the concentration of BCAA by dietary restriction of these amino
acids. Because BCAA belong to the essential amino acids, the dietary treatment requires frequent
adjustment, which is accomplished by regular determination of BCAA and Allo-Ile concentrations.
Useful For: Evaluation of newborn screening samples that test positive for branched-chain amino acids
elevations Follow-up of patients with maple-syrup urine disease
Interpretation: Allo-isoleucine is nearly undetectable in individuals not affected by maple-syrup urine
disease (MSUD). Accordingly, its presence is diagnostic for MSUD, and its absence is sufficient to
rule-out MSUD.
Reference Values:
Allo-isoleucine: