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.
Matteucci
E
E
Cattedra di Malattie del Metabolismo, Istituto di Clinica Medica II, Università degli Studi di Pisa, Italy.
Gregori
G
G
Pellegrini
L
L
Navalesi
R
R
Giampietro
O
O
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