Plasma and Urine Aminolevulinic Acid
Urinary and plasma aminolevulinic acid (ALA) and porphobilinogen (PBG) measurements are used in the clinical diagnosis and monitoring of the acute porphyrias, a group of inborn errors of heme biosynthesis. These include autosomal dominant acute intermittent porphyria (AIP), hereditary coproporphyria (ADP), variegate porphyria (VP), and autosomal recessive ALA-dehydratase deficient porphyria (ADP). Gene mutations alone are not sufficient to produce symptoms of these disorders; other activating factors, such as drugs, hormones, and dietary changes must be present.
The characteristic acute attacks almost always start with severe pain in the abdomen but sometimes in the chest, back, or thighs, and are often accompanied by nausea, vomiting, and constipation. Heart rate and blood pressure are commonly increased. These symptoms and signs are all due to the effects of the disease on the nervous system. Confusion, convulsions, and muscular weakness due to impairment of the nerves controlling the muscles may lead to paralysis. An acute attack usually lasts for days or weeks. Recovery from severe paralysis is generally slow.
The diagnostic hallmark of an acute attack is the marked increase of plasma and urinary concentrations of the porphyrin precursors, ALA and PBG, particularly urinary PBG. In the three autosomal dominant acute porphyrias, ALA and PBG levels are normal or slightly increased in asymptomatic patients, but may be increased 200-fold over presymptomatic levels during an acute attack. In ADP, the ALA levels are consistently elevated, but increases occur during the acute attacks. Elevated urinary and plasma ALA cna also be found in patients with lead poisoning (LP) and hereditary tyrosinemia Type I (HT1). Testing is performed by liquid chromatography and tandem mass spectrometry.
Plasma: One 5 ml tube of anticoagulated blood in sodium heparin (green top); draw in amber tube or protect from light by wrapping in foil. Centrifuge immediately and freeze plasma.
Urine: 5 ml (random void) in a clean container without preservatives. Protect from light by wrapping in foil and freeze.
Shipping: Ship overnight frozen on dry ice.
5 days for routine samples.
Same day results available on an emergency basis.
Please call the laboratory prior to sending a sample for STAT analysis.
CPT Codes: 82135, 83789
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