24 hour urine refrigerated during collection. Record total
volume. Transfer 10 mL from a well-mixed 24 hr collection
to a plastic aliquot tube. Freeze. Critical Frozen (CFZ).
A completed history form must accompany sample (include
patient age, gender, diet (i.e. Tpn therapy), drug therapy
and family history). When multiple tests are ordered,
submit separate sample for this test.