|
Amino acids are components of all of the body's proteins, both
enzymatic and nonenzymatic. Any abnormality in the metabolism
of amino acids may lead to mental retardation or other problems.
In some of the amino acid disorders, treatment may prevent mental
retardation or other handicaps.
Amino acid analysis is usually performed on plasma (serum) or
urine. In certain circumstances, it may be performed on cerebrospinal
fluid or other tissues. Disturbances of amino acid metabolism
may be suspected in infants or children who have:
- feeding abnormalities
- growth failure
- development failure
- seizures
- unexplained acidosis (uncommon)
- elevated blood ammonia
Specimen requirements: Amino acid analysis may be performed
on any fluid in the body (urine, plasma or serum, spinal fluid,
amniotic fluid). For metabolic studies, urine (at least 10 ml
of a random catch; 24-hour collection preferred) and plasma (at
least 1 ml) are usually analyzed. Plasma is the preferred tissue
for amino acid quantitation because urine amino acid values are
based on creatinine concentration and the concentration of urine
varies greatly which can falsely elevate or lower values. Unless
there is the suspicion of a transport defect, i.e. cystinuria,
plasma is the preferred specimen.
Transport: Samples (plasma, serum, or urine) must be frozen,
preferably on dry ice. Samples must be received within 24 hours
by overnight delivery services or courier. Do not freeze whole
blood.
Standard of analysis: Quantitative analysis will be
done by ion-exchange high performance liquid chromatography (Beckman 6300
system).
Time required: Analysis will usually be complete within
three days.
Special requests: Any type of special request,
including STAT assays, must be made directly with the laboratory at the time the
specimen is submitted.
Report: Written reports will be mailed, and when
abnormalities exist, a report will be given by telephone. Elevations of any
amino acid level will be noted and compared to normal levels with
interpretation. Reports may be sent by FAX or email if requested.
CPT Code: 82139 (x20)
|
