δ-a·mi·no·lev·u·lin·ic ac·id (ALA),(ă-mē'nō-lev-yū-lin'ik as'id),
An acid formed by δ-aminolevulinate synthase from glycine and succinyl-coenzyme A; a precursor of porphobilinogen, hence an important intermediate in the biosynthesis of heme. Plasma levels are elevated in cases of lead poisoning.
To assist in diagnosing lead poisoning in children, or porphyria, a disorder that disrupts heme synthesis, primarily affecting the liver.
SpecimenUrine (25 mL) from a timed specimen collected in a dark plastic container with glacial acetic acid as a preservative.
|Conventional Units||SI Units (Conventional Units × 7.626)|
|1.5–7.5 mg/24 hr||11.4–57.2 micromol/24 hr|
δ-Aminolevulinic acid (δ-ALA) is involved in the formation of porphyrins, which ultimately leads to hemoglobin synthesis. Toxins including alcohol, lead, and other heavy metals can inhibit porphyrin synthesis. Accumulated δ-ALA is excreted in urine. Symptoms of the acute phase of intermittent porphyrias include abdominal pain, nausea, vomiting, neuromuscular signs and symptoms, constipation, and occasionally psychotic behavior. Hemolytic anemia may also exhibit during the acute phase. δ-ALA is a test of choice in the diagnosis of acute intermittent porphyria. Although lead poisoning can cause increased urinary excretion, the measurement of δ-ALA is not useful to indicate lead toxicity because it is not detectable in the urine until the blood lead level approaches and exceeds 40 mcg/dL, the level at which children should be evaluated to determine the need for chelation therapy.
This procedure is contraindicated for
- Assist in the diagnosis of porphyrias
Related to inhibition of the enzymes involved in porphyrin synthesis; results in accumulation of δ-ALA and is evidenced by exposure to medications, toxins, diet, or infection that can precipitate an attack
- Acute porphyrias
- Aminolevulinic acid dehydrase deficiency (related to the inability to convert δ-ALA to porphobilinogen, leading to accumulation of δ-ALA)
- Hereditary tyrosinemia
- Lead poisoning
|Conventional Units||SI Units (Conventional Units × 7.62)|
|Greater than 20 mg/24 hr||Greater then 152.4 micromol/24 hr|
- Drugs that may increase δ-ALA levels include penicillins.
- Cimetidine may decrease δ-ALA levels.
- Numerous drugs are suspected as potential initiators of attacks of acute porphyria, but those classified as unsafe for high-risk individuals include aminopyrine, apronalide, barbiturates, chlordiazepoxide, chlorpropamide, diazepam, dichloralphenazone, ergot preparations, glutethimide, griseofulvin, hydantoin derivatives, isopropyl dipyrone, meprobamate, methyldopa, methylsulfonal, methyprylone, oral contraceptives, pentazocine, phenytoin, progestogens, succinimide, sulfonmethane, and tolbutamide.
Nursing Implications and Procedure
- Positively identify the patient using at least two unique identifiers before providing care, treatment, or services.
- Patient Teaching: Inform the parent/patient this test can assist with identification of poisoning from lead or other toxins.
- Obtain a history of the patient’s complaints, including a list of known allergens, especially allergies or sensitivities to latex.
- Obtain a history of the patient’s hematopoietic system, symptoms, and results of previously performed laboratory tests and diagnostic and surgical procedures.
- Obtain a list of the patient’s current medications, including herbs, nutritional supplements, and nutraceuticals (see Effects of Natural Products on Laboratory Values).
- Review the procedure with the patient. Provide a nonmetallic urinal, bedpan, or toilet-mounted collection device. Address concerns about pain and explain that there should be no discomfort during the procedure.
- Usually a 24-hr time frame for urine collection is ordered. Inform the patient that all urine must be saved during that 24-hr period. Instruct the patient not to void directly into the laboratory collection container. Instruct the patient to avoid defecating in the collection device and to keep toilet tissue out of the collection device to prevent contamination of the specimen. Place a sign in the bathroom to remind the patient to save all urine.
- Instruct the patient to void all urine into the collection device and then to pour the urine into the laboratory collection container. Alternatively, the specimen can be left in the collection device for a health-care staff member to add to the laboratory collection container.
- Sensitivity to social and cultural issues, as well as concern for modesty, is important in providing psychological support before, during, and after the procedure.
- Note that there are no food, fluid, or medication restrictions unless by medical direction.
- Potential complications: N/A
- Avoid the use of equipment containing latex if the patient has a history of allergic reaction to latex.
- Instruct the patient to cooperate fully and to follow directions.
- Observe standard precautions, and follow the general guidelines in Patient Preparation and Specimen Collection. Positively identify the patient, and label the appropriate specimen container with the corresponding patient demographics, initials of the person collecting the specimen, date, and time of collection.
- Obtain a clean 3-L urine specimen container, toilet-mounted collection device, and plastic bag (for transport of the specimen container). The specimen must be refrigerated or kept on ice throughout the entire collection period. If an indwelling urinary catheter is in place, the drainage bag must be kept on ice.
- Begin the test between 6 and 8 a.m. if possible. Collect first voiding and discard. Record the time the specimen was discarded as the beginning of the timed collection period. The next morning, ask the patient to void at the same time the collection was started, and add this last voiding to the container. Urinary output should be recorded throughout the collection time.
- Replace the tubing and container system at the start of the collection time if an indwelling catheter is in place. Keep the container system on ice during the collection period, or empty the urine into a larger container periodically during the collection period. Monitor to ensure continued drainage, and conclude the test the next morning at the same hour the collection was begun.
- Compare the quantity of urine with the urinary output record for the collection at the conclusion of the test. If the specimen contains less than what was recorded as output, some urine may have been discarded, invalidating the test.
- Include on the specimen collection container’s label the amount of urine as well as test start and stop times. Note the ingestion of any medications that may affect test results.
- Promptly transport the specimen to the laboratory for processing and analysis.
- Inform the patient that a report of the results will be made available to the requesting HCP, who will discuss the results with the patient.
- Nutritional Considerations: Increased δ-ALA levels may be associated with an acute porphyria attack. Patients prone to attacks should eat a normal or high-carbohydrate diet. Dietary recommendations may be indicated and will vary depending on the condition and its severity; however, restrictions of or wide variations in dietary carbohydrate content should be avoided, even for short periods of time. After recovering from an attack, the patient’s daily intake of carbohydrates should be 300 g or more per day.
- Recognize anxiety related to test results. Discuss the implications of abnormal test results on the patient’s lifestyle. Provide teaching and information regarding the clinical implications of the test results, as appropriate. Provide contact information, if desired, for the American Porphyria Foundation (www.porphyriafoundation.com).
- Reinforce information given by the patient’s HCP regarding further testing, treatment, or referral to another HCP. Answer any questions or address any concerns voiced by the patient or family.
- Depending on the results of this procedure, additional testing may be performed to evaluate or monitor progression of the disease process and determine the need for a change in therapy. Evaluate test results in relation to the patient’s symptoms and other tests performed.
- Related tests include CBC, erythrocyte protoporphyrin (free), lead, and porphyrins urine.
- See the Hematopoietic System table at the end of the book for related tests by body system.
a precursor of porphyrins and hemoglobin. Serum levels of the acid are elevated in lead poisoning. See also aminolevulinate dehydratase.
see δ-aminolevulinic acid.