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Extraction of glyceric and glycolic acids from urine with tetrahydrofuran: utility in detection of primary hyperoxaluria

Departments of
¹ Pathology,
² Internal Medicine, and
³ Pediatrics, Washington University School of Medicine, St. Louis, MO 63110.
⁴ Department of Internal Medicine, Division of Nephrology, Mayo Medical Center, Rochester, MN 55905.

⁵ Current address: Dade Chemistry Systems, Inc., Bldg. 700, Box 707, Newark, DE 19714-6101.

⁶ This author is an employee of the US Air Force: The opinions and conclusions in this paper are those of the authors, and do not represent the official position of the Department of Defense, the US Air Force, or any other government agency.

⁷ Nonstandard abbreviations: AGT, alanine:glyoxylate aminotransferase; GDH, D-glycerate dehydrogenase; PH, primary hyperoxaluria; PH I (II), primary hyperoxaluria type I (type II); GC-MS, gas chromatography–mass spectrometry; THF, tetrahydrofuran; and BSTFA, bis(trimethylsilyl)trifluoroacetamide.
^a Author for correspondence. Fax 314-454-2274; email landt{at}kids.wustl.edu

Primary hyperoxaluria (PH) is an autosomal recessive metabolic abnormality characterized by excessive oxalate excretion leading to nephrocalcinosis and progressive renal dysfunction. Type I primary hyperoxaluria (PH I) results from a deficiency of alanine:glyoxylate aminotransferase, whereas type II disease has been traced to a deficiency of D-glycerate dehydrogenase. The two syndromes are often distinguished on the basis of organic acids that are coexcreted with oxalate: glycolate and L-glycerate in type I and type II disease, respectively. Routine organic acid analysis with diethyl ether extraction followed by gas chromatographic analysis failed to detect normal and increased concentrations of these diagnostic metabolites. Subsequent extraction of urine with tetrahydrofuran (THF), however, extracted 75% of added glycerate, 42% of added glycolate, and 75% of added ethylphosphonic acid (internal calibrator). THF extraction was analytically sensitive enough to allow determination of normal excretion of glycolate (14–72 µg/mg creatinine) and glycerate (0–5 years, 12–177 µg/mg creatinine and >5 years, 19–115 µg/mg creatinine). Four of five patients with PH I and both patients with type II disease were correctly identified. Thus, THF extraction is a convenient adjunct to routine organic acid analysis and facilitates the detection of PH.

Key Words: indexing terms: inborn errors of metabolism • oxalates • renal calculi • laboratory diagnosis • gas chromatography

The following articles in journals at HighWire Press have cited this article:

				G. Rumsby and C. Samuell Availability of Assays for Definitive Diagnosis of Primary Hyperoxaluria Types 1 and 2 Clin. Chem., March 1, 1998; 44(3): 694 - 694. [Full Text] [PDF]