78006-4

LOINC code 78006-4 identifies "Isotopic Glomerular filtration rate/1.73 sq M [Volume Rate/Area] in Urine and Serum or Plasma". This test measures kidney filtration after injection of a radioactive tracer (e.g. technetium 99m DTPA). It is an actual measurement of glomerular filtration rate (GFR). The test is a several hour long kidney function test typically performed to accurately verify the level of renal dysfunction. It requires sequential collection of both blood and urine specimens after the tracer injection. Isotopic GFR may be used for monitoring renal function over time, or in chronic renal failure patients approaching dialysis. [PMID: 1391702] The submitter's lab uses the following formula to determine GFR: GFR = (UV/P) x (1.73/BSA) Where, for each timed urine collection, U = (urine collection CPM = UbkgCPM) V = urine flow rate: (urine volume / elapsed time) in units of mL/min P = (average serum or plasma CPM = Bbkg CPM) The average serum CPM (counts per minute) will be the average of Bo and B1 for the first urine collection (U1) and the average of B1 and B2 for the second collection (U2). Average the calculated GFR results for the two collection periods to obtain the final GFR result.

This code measures Glomerular filtration rate in Urine+Ser/Plas. It belongs to the CHEM class in the LOINC classification.

LOINC (Logical Observation Identifiers Names and Codes) is a universal standard for identifying laboratory and clinical observations. It is maintained by the Regenstrief Institute and used worldwide for health data exchange.