Urea
Definition
A product of protein catabolism excreted primarily in urine, present at 200 to 400 mmol per litre. Also present at lower concentrations in sweat, so less specific to urine alone.
- Origin
- Protein catabolism byproduct
- Urine concentration
- 200 to 400 mmol per litre
- Also found in
- Sweat, at lower concentration
- Specificity
- Low alone; needs a combined marker panel
Common questions
Why can't urea alone confirm a urine stain?+
Because urea is also present in sweat, a positive urea test cannot distinguish urine from sweat contamination on fabric. Analysts pair it with creatinine or uric acid, which are far more urine-specific, before reporting a urine identification.
Does urea concentration change with hydration or diet?+
Yes, urea output rises with high protein intake and falls with dilute urine from overhydration, which is one reason forensic urine identification relies on a marker panel rather than urea concentration alone.
Related terms
- Creatinine
- A breakdown product of creatine phosphate in muscle. It is filtered by the kidneys and excreted in urine at relatively constant rates,...
- Dermcidin
- An antimicrobial peptide secreted constitutively by eccrine sweat glands. The primary candidate marker for immunological identification of sweat in forensic samples, though...
- Eccrine Glands
- The primary sweat glands distributed across most body surfaces, producing a watery secretion mainly of water, sodium chloride, and trace amounts of...
- RSID-Urine
- Rapid Stain Identification of Urine. An immunochromatographic lateral-flow assay that detects Tamm-Horsfall protein in biological extracts, providing a highly specific confirmatory test...
- Tamm-Horsfall Protein (Uromodulin)
- The most abundant protein in normal human urine, secreted exclusively by cells of the thick ascending limb of Henle's loop in the...