Biomarkers · Chemical
We have not added a physiological summary for this biomarker yet. Compare the commercial laboratory assays and population reference ranges below.
Check orderable catalog codes, specimen types, fasting requirements, and demographic reference ranges across laboratories.
Laboratory assay overview
This test is used for people with known cystinuria, cystine stone formers or patients who had a reported "positive" screen from the standard Litholink test, Litholink 24-Hour Urine, KS [910235].
Labcorp test directory, test code 910245
Laboratory assay overview
This test is used for treatment and management of known or suspected kidney stone formers.
Labcorp test directory, test code 910235
Laboratory assay overview
Renal function test
Labcorp test directory, test code 317222
Laboratory assay overview
Renal function test
Labcorp test directory, test code 002329
Laboratory assay overview
Renal function test; coarse nitrogen-wasting test on patients on hyperalimentation; indicate nitrogen balance in hyperalimentation; rule out tap of urinary bladder in amniocentesis, paracentesis
See table. Age Male (g/24 hr) Female (g/24 hr) 0 to 5 y Not established Not established 6 to 17 y 3–21 2–13 18 to 70 y 5–22 4–16 >70 y 4–16 2–12
Labcorp test directory, test code 003541
Laboratory assay overview
This quantitative urea nitrogen test, performed with a 24-hour urine specimen, may help estimate nitrogen balance and determine protein need in patients in critical conditions or receiving intravenous administration of nutrition [1]. Urea is the main nitrogen-containing product of protein breakdown and makes up over 75% of total nonprotein nitrogen excreted. Approximately 90% of the urea excretion is through the kidneys, and the rest is through gastrointestinal tract and skin. Because urea secretion is closely related to protein catabolism, urinary urea, commonly expressed by the concentration of urinary urea nitrogen, may be used to assess nitrogen balance and guide protein intake [1,2]. Blood and urinary urea levels were previously used as kidney function markers but are only considered useful in certain clinical scenarios; they have been generally replaced by creatine levels [1]. Urinary urea nitrogen level may be increased in individuals with hyperthyroidism or excess protein intake or breakdown [3]. It may be decreased in individuals with malnutrition, kidney damage or insufficiency, low-protein and high-carbohydrate diet, or liver disease. Pregnant persons and healthy children may also have low urinary nitrogen levels [3]. The results of this test should be interpreted in the context of pertinent clinical and family history and physical examination findings. References 1. Lamb EJ, et al. Kidney function tests. Rifai N, et al. eds. Tietz Textbook of Laboratory Medicine. 7th ed. Elservier Inc; 2022 2. Oh MS, et al. Evaluation of renal function, water, electrolytes, and acid-base balance. In: McPherson RA, et al, eds. Henry's Clinical Diagnosis and Management by Laboratory Methods. 24th ed. Elsevier; 2021 3. Rao LV, et al. Laboratory tests. In: Rao LV, eds. Wallach's Interpretation of Diagnostic Tests. Pathways to Arriving at a Clinical Diagnosis. 11th ed. Wolters Kluwer; 2020.
6-17 g/24 h
Quest Diagnostics test directory, test code 973
We compile every detail above directly from named laboratory directories and published clinical studies. Laboratories calculate standard reference intervals from the statistical distribution of tested populations for a specific assay method and demographic group, rather than setting universal optimal targets.
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