Test Library

Preferred Specimen(s) 10 mL urine

Transport Container 24-hour urine container

Instructions Refrigerate during and after collection. Record 24 hour urine volume, on the test requisition form, as well as on the urine vial.

Collect 24-hour urine in the presence of 10 grams boric acid.

Transport Temperature Refrigerated, stable 1 week

Reject Criteria

  • Received at room temperature;
  • Received frozen

Methodology Specterophotometry

Clinical Significance Urea is the principle waste product of protein catabolism. Urea nitrogen is most commonly measured in the diagnosis and treatment of certain renal and metabolic diseases. Increased urea nitrogen concentration may result from increased production of urea due to (1) diet or excessive destruction of cellular proteins as occurs in massive infection and fevers, (2) reduced renal perfusion resulting from dehydration or heart failure, (3) nearly all types of kidney disease, and (4) mechanical obstruction to urine excretion such as is caused by stones, tumors, infection, or stricture. Decreased urea levels are less frequent and occur primarily in advanced liver disease and in over-hydration.