Draw blood in a 7 mL lavender-top (EDTA) tube from a fasting (12 hour) patient. Spin down, decant, and send 2.5 mL (2.0 minimum) of EDTA plasma refrigerated. Do not analyze samples that show visible signs of hemolysis. Note: Stable 24 hours unspun (whole blood) at both ambient and refrigerated temperatures. Once decanted, EDTA plasma is stable for 48 hours at room temperature, 72 hours refrigerated, or 6 months frozen. “PTH samples should not be taken from patients receiving therapy with high biotin doses (i.e. > 5 mg/day) until at least 8 hours after the last biotin administration.”
Stability
Room temperature: 2 days Refrigerated: 3 days Frozen: 6 months
