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Test Code BUAUC Busulfan, Intravenous Dose, Area Under the Curve, Plasma

Reporting Name

Busulfan, IV Dose, AUC, P

Performing Laboratory

Mayo Clinic Laboratories in Rochester

Useful For

Guiding dosage adjustments to achieve complete bone marrow ablation while minimizing dose-dependent toxicity

Method Name

Liquid Chromatography Tandem Mass Spectrometry (LC-MS/MS)


Necessary Information


The time the drug administration is started and completed, the patient's dose (mg every 6 hours), body weight (kg), and age (years) must be submitted with the specimens. Without infusion start time, exact time of specimen collection, dose, and body weight, the area under the curve and clearance cannot be calculated. Age is required for assessment of the correct dose per body weight.

 

A completed Busulfan Information: Mail-In Specimen Instructions (T559) is required.



Specimen Required


Four plasma specimens with different collection times (keep all specimens under 1 order) are required.

 

Collection Container/Tube: Green top (sodium heparin) (Plasma gel/PST are not acceptable)

Submission Container/Tube: Plastic vials

Specimen Volume: 1 mL

Collection Instructions:

1. The first specimen should be collected immediately after completion of the first intravenous infusion of 0.8 mg/kg busulfan.

2. Additional specimens should also be collected at 1 hour, 2 hours, and 4 hours after completion of infusion.

3. Label each specimen with exact time of collection.

4. Busulfan degrades quickly at ambient temperature. Specimens must be kept in wet ice slurry or refrigerated at 4° C. Specimens must be centrifuged within 2 hours after collection. Separate the plasma and transfer to individual 5-mL plastic vials, labeled with exact time of collection. Immediately freeze at -20° C.

Additional Information:

This test should only be ordered when the following criteria are met:

-Busulfan dosing protocol must be intravenous administration of 0.8 mg/kg doses every 6 hours over 4 days, for a total of 16 doses

Specimens must be collected as described below:

-1 specimen collected immediately after completion of the first 2-hour IV infusion of busulfan

-1 specimen collected 1 hour after the infusion is completed

-1 specimen collected 2 hours after the infusion is completed

-1 specimen collected 4 hours after the infusion is completed and prior to the next infusion of busulfan


Specimen Type

Plasma Na Heparin

Specimen Minimum Volume

0.25 mL

Specimen Stability Information

Specimen Type Temperature Time Special Container
Plasma Na Heparin Frozen (preferred) 28 days
  Refrigerated  72 hours

Reject Due To

Gross hemolysis OK
Gross lipemia OK
Gross icterus OK

Reference Values

AREA UNDER THE CURVE

900-1500 (mcmol/L)(min)

 

CLEARANCE

2.1-3.5 (mL/minute)/kg

Interpretation

Results of the timed collections will be used to calculate a 6-hour area under the curve (AUC). If a different dosing or specimen collection protocol is used, or if different calculations are required, contact the Laboratory Director.

 

The optimal result for AUC (6 hour) derived from this pharmacokinetic evaluation of IV busulfan is 1100 (mcmol/L)(min).

 

Area under the curve results greater than 1500 (mcmol/L)(min) are associated with hepatic veno-occlusive disease. A dose reduction should be considered before the next busulfan infusion.

 

Area under the curve results below 900 (mcmol/L)(min) are consistent with incomplete bone marrow ablation. A dose increase should be considered before the next busulfan infusion.

 

Clearance of busulfan in patients with normal kidney function is usually in the range of 2.1 to 3.5 (mL/min)/kg.

 

Elevated AUC is typically associated with clearance below 2.5 (mL/min)/kg, most frequently due to diminished activity of glutathione S-transferase A1-1 activity.(3)

Day(s) Performed

Monday through Saturday

Report Available

Same day/1 to 3 days

Test Classification

This test was developed and its performance characteristics determined by Mayo Clinic in a manner consistent with CLIA requirements. It has not been cleared or approved by the US Food and Drug Administration.

CPT Code Information

80299 x 4

LOINC Code Information

Test ID Test Order Name Order LOINC Value
BUAUC Busulfan, IV Dose, AUC, P 93478-6

 

Result ID Test Result Name Result LOINC Value
DRDT2 Draw Date 33882-2
DRDT3 Draw Date 33882-2
DRDT4 Draw Date 33882-2
DRDT6 Draw Date 33882-2
DSE Initial Dose 93477-8
DAT16 Infusion Start Date 88063-3
DRTM6 Draw Time 49049-0
DRTM4 Draw Time 49049-0
DRTM3 Draw Time 49049-0
DRTM2 Draw Time 49049-0
24221 Busulfan result 93436-4
24222 Busulfan result 93435-6
24223 Busulfan result 93434-9
24224 Busulfan result 93433-1
TM82 Infusion Start Time 88060-9
DAT17 Infusion Stop Date 88062-5
TM65 Infusion Stop Time 88061-7
W8 Weight 29463-7
24220 Age 30525-0
24225 Area Under the Curve, (0-6 Hour) 93476-0
24226 Clearance 93475-2
24227 Recommended Dose 93477-8

Forms

1. Busulfan Information: Mail-In Specimen Instructions (T559) is required

2. If not ordering electronically, complete, print, and send a Therapeutics Test Request (T831) with the specimen.

Profile Information

Test ID Reporting Name Available Separately Always Performed
DOSE Busulfan, IV Dose, AUC, P No Yes
BU2H Busulfan, Immediate Post Infusion No Yes
BU3H Busulfan, 1hr Post Infusion No Yes
BU4H Busulfan, 2hr Post Infusion No Yes
BU6H Busulfan, 4hr Post Infusion No Yes