Salicylate, Serum
| Salicylate, Serum | | | |
| Number | | 007849 |
| CPT | | 80196 |
| Synonyms | | Acetylsalicylic Acid, Blood ; Aspirin, Blood ; Salicylic Acid, Blood |
| Specimen | | Serum or plasma |
| Volume | | 2 mL |
| Minimum Volume | | 0.6 mL |
| Container | | Red-top tube or green-top (heparin) tube |
| Collection | | Transfer separated serum or plasma to a plastic transport tube. Do not use a gel-barrier tube. The use of gel-barrier tubes is not recommended due to slow absorption of the drug by the gel. Depending on the specimen volume and storage time, the decrease in drug level due to absorption may be clinically significant. Optimal sampling time after dosage is 2-6 hours. Optimal resampling time after change in dosage is 6 hours. |
| Storage Instructions | | Refrigerate |
| Causes for Rejection | | Gel-barrier tube |
| Reference Interval | | Therapeutic (anti-inflammatory): 30-250 μg/mL |
| Critical Values | | Potentially toxic: >300 μg/mL |
| Methodology | | Immunoassay |
| Additional Information | | Optimal sampling time after dosage is 2-6 hours. Serum half-life is 2-3 hours on low-dose therapy, 15-30 hours on high-dose treatment. Optimal resampling time after change in dosage is 6 hours. In patients on chronic therapy, small dose changes may produce disproportionate changes in serum level. Use of antacids, which increase renal excretion, can lower serum levels. Steady-state concentrations for an individual patient are not adequately predicted from nomograms or standard dose schedules. In salicylate poisoning, the following symptoms may occur: initial alkalosis followed by acidosis in the blood, ketosis, and possible elevated plasma glucose. Glucose should be measured when levels >250 μg/mL are detected. Salicylate can be done on urine or gastric juice. The following Done nomogram is used to estimate blood level and prognosis following a single dose ingestion. The level measured 4 hours or more following ingestion is plotted. Specimens drawn earlier may not reflect the peak. The nomogram is not useful when accumulation over several ingestions exists. Urine pH and volume hourly are advocated with plasma pH, potassium and other electrolytes, prothrombin time, AST, ALT, serum bilirubin, and arterial blood gases for care of serious pediatric salicylate poisoning.1
 Salicylate hepatitis, usually at blood levels of 200-250 μg/mL, occurs. Salicylates are believed to play a role in the hepatonecrosis of Reye syndrome in children. They are no longer recommended for use in children. |
| Footnotes | | - Paulson JA, “Poisonings From Food, Drugs, Chemicals, Pollutants, and Venomous Bites; Mammalian Bites,” Nelson Textbook of Pediatrics, 13th ed, Behrman RE, Vaughn VC III, and Nelson WE, eds, Philadelphia, PA: WB Saunders Co, 1987, 1491, 1516
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