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A B C D E F G H I J K L M N O P Q R S T U V W X Y Z # |
Oxalic Acid, Pediatric Urine [11222X]
Test CodeCPT Codes
82570, 83945
Preferred Specimen
Patient Preparation
Patient should refrain from taking excessive amounts of Ascorbic Acid or Oxalate-rich foods (i.e., spinach, coffee, tea, chocolate, rhubarb) for at least 48 hours before the collection period.
Minimum Volume
Instructions
Please submit second morning voided specimen
Transport Temperature
Specimen Stability
Refrigerated: 7 days
Frozen: 24 days
Methodology
Spectrophotometry
Setup Schedule
Reference Range
Age | Male (mg/mg creat) |
Female (mg/mg creat) |
< 1 month | Not established | Not established |
1-5 months | 0.05-0.18 | 0.05-0.18 |
6-11 months | 0.04-0.14 | 0.04-0.14 |
1 year | 0.04-0.11 | 0.04-0.11 |
2 years | 0.03-0.08 | 0.03-0.08 |
3-4 years | 0.02-0.07 | 0.02-0.07 |
5-6 years | 0.02-0.06 | 0.02-0.06 |
7-17 years | 0.01-0.05 | 0.01-0.05 |
> 17 years | <0.03 | <0.04 |
Clinical Significance
This test is often used to screen for hyperoxaluria and assess kidney function in children. It can help to determine the cause of kidney stones and monitor treatment [1].
Oxalic acid is an organic compound that naturally exists in many food sources. Because humans cannot metabolize oxalic acid, it must be excreted in urine as oxalate (the ionic form of oxalic acid). Excessive excretion of oxalates is called hyperoxaluria and can be attributed to primary or secondary causes. Primary hyperoxaluria (PH) is a rare condition resulting from enzymatic defects and can lead to chronic kidney disease, which may progress to kidney failure. Secondary hyperoxaluria can be caused by fat malabsorption, which may be due to inflammatory bowel disease, extensive resection of the small bowel, or excessive ingestion of substances that increase serum oxalates [2].
PH is associated with significant morbidity and mortality, including end-stage renal disease [1]. By itself, PH accounts for 7% to 14% of nephrocalcinosis cases among children [3]. PH is treatable. Early diagnosis is associated with better outcomes, but more than 40% of PH diagnoses are delayed [1]. The National Organization of Rare Diseases (NORD)
recommends metabolic screening of all children with nephrolithiasis or nephrocalcinosis [4].
Results from this test should be interpreted in the context of pertinent clinical and family history and physical examination findings.
References
1. Bhasin B, et al. World J Nephrol. 2015;4(2):235-244.
2. Shchelochkov O, et al. Defects in metabolism of amino acids. In: Kliegman R, at al. Nelson Textbook of Pediatrics. 21st ed. Elsevier; 2019:720-722.
3. Hulton S-A. Int J Surg. 2016;36(Pt D):649-654.
4. NORD. Primary hyperoxaluria. Accessed September 2,2021.
https://rarediseases.org/rare-diseases/primary-hyperoxaluria/
Performing Laboratory
Quest Diagnostics Nichols Institute
14225 Newbrook Drive
Chantilly, VA 20153