Effects of storage time and temperature on urinary enzymes.
We measured three renal tubular brush-border enzymes (lactate dehydrogenase, LDH, EC 1.1.1.27; gamma-glutamyltransferase, GGT, EC 2.3.2.2; and alkaline phosphatase, AP, EC 3.1.3.1) in morning urine samples from 48 healthy subjects to check whether different storage times and temperatures could modify enzyme concentrations. Short-term (24 h) storage time at room temperature or 4 degree C does not affect urinary enzyme activity. A few days of freezing, at -20 or -70 degrees C, dramatically lowers LDH and AP values; GGT is partially preserved only at -70 degrees C, if the sample has been previously centrifuged. Urinary enzymes investigated in this study are extremely labile at low temperatures.
Cattedra di Malattie del Metabolismo, Istituto di Clinica Medica II, Università degli Studi di Pisa, Italy.
E
E
Matteucci
G
G
Gregori
L
L
Pellegrini
R
R
Navalesi
O
O
Giampietro
D000469:Alkaline Phosphatase / Q000652:urine*; D006801:Humans; D007684:Kidney Tubules / Q000201:enzymology*; D007700:Kinetics; D007770:L-Lactate Dehydrogenase / Q000652:urine*; D008871:Microvilli / Q000201:enzymology*; D011309:Preservation, Biological; D012016:Reference Values; D013056:Spectrophotometry, Ultraviolet; D013696:Temperature; D013997:Time Factors; D005723:gamma-Glutamyltransferase / Q000652:urine*
D007770:L-Lactate Dehydrogenase; D005723:gamma-Glutamyltransferase; D000469:Alkaline Phosphatase