Serum: Collect blood in a royal blue trace element tube, no preservative (serum). Allow specimen to clot for 30 minutes, centrifuge, and carefully pour serum into a metal-free container, avoiding transfer of the cellular components of blood. Do not insert a pipet into the serum to transfer and do not ream the specimen with a wooden stick to assist with the transfer. Refrigerate up to 48 hours or freeze for longer storage. Urine: Collect 24 hour urine in a clean, plastic container with no metal cap or glued insert and no preservative. Aliquot urine into a clean, plastic container with no metal cap or glued insert and refrigerate within 4 hours of completion of collection. Record 24 hour urine volume and collection dates/times on the request form. Collection must take place prior to or 48 hours after administering gadolinium-containing contrast media.