METABOLIC SCREEN, QUALITATIVE, URINE
- METABOLIC SCREEN, QUALITATIVE, URINE
- Start Date
- Expiration Date
- Inborn Errors of Metabolism Screen; Urine Genetic/Metabolic Screen
- CPT Codes
- 81005x2; 82128; 82615; 83866; 83918
- Reference Test
- Transport Info
CRITICAL FROZEN Specimen MUST BE FROZEN immediately and KEPT FROZEN.
- Fasting Required?
- Patient Instructions
DO NOT increase fluid intake, as dilution reduces the sensitivity of some tests.
Form required: Indiana University Pediatric Biochemical Genetics Requisition
- Reference Range
Unidimensional thin-layer electrophoresis (TLE)
Cyanide-Nitroprusside Spot Test
Dinitrophenylhydrazine Spot Test
Toluidine Blue Spot Test
Gas Chromatography/Mass Spectrometry (GC/MS)
An estimated 500 inborn errors of metabolism are now known. Screening tests may be useful in limited circumstances, but are obsolete for the vast majority of cases. The following tests are preferred to evaluate potential inborn errors of metabolism: Amino Acids Quantitative, Plasma; Amino Acids Quantitative, Urine; Organic Acids, Urine; and Acylcarnitine (Quantitative) Profile, Plasma.
Abnormal pH is often an indication of specimen collection and/or handling problems. The presence of protein, glucose, ketones, or blood may interfere with the screening tests. Clinitest detects reducing substances such as glucose, galactose, fructose, lactose, and pentoses. CTAB (cetyltrimethylammonium bromide), acid albumin, and the berry spot test are screening tests that detect certain mucopolysaccharides. Nitroanaline detects massive elevations of methylmalonic acid. DNPH (dinitrophenylhydrazine) is a screening test for ketoacids. Ferric chloride is a screening test for phenylketones. Nitroprusside screens for massive elevations of cystine and homocystine. Common reasons for false negative results include collection of dilute urine, intermittent excretion of abnormal metabolites, collection after the start of supportive therapy, and the presence of protein, glucose, ketones, or blood. Abnormal pH may indicate specimen handling problems. Drug therapy is a common reason for false positive results.