October 2021: TFTEST – Temporary Change in Performing Send-out Laboratory

Immediate Test Change

TFTEST – Temporary Change in Performing Send-out Laboratory

November 4, 2021 – Update: Testosterone, Total and Free, Serum (TFTEST) has resumed being performed by Mayo Clinic Laboratories, the test’s original standard reference laboratory.

This change occurs automatically for TFTEST samples received by Mayo Clinic. Samples received prior to November 4, 2021, will be resulted from the temporary reference laboratory, Quest Diagnostics.

Refer to the details provided below for further information.

Testosterone, Total and Free, Serum (TFTEST) – Temporary Changes

Effective October 25, 2021.

Original Communication:

Beginning October 25, 2021, Testosterone, Total and Free, Serum (TFTEST) will be temporarily sent to an alternate reference laboratory (Quest Diagnostics).

This will occur automatically for new TFTEST samples received by Cleveland Clinic Laboratories.

Methodology

Methodology
The assays performed by both reference laboratories employ the same method, but there will be two main changes to the results:

1. Units of reporting for free testosterone will change from ng/dL to pg/mL.

Conversion factors:

  • Testosterone, free (ng/dL) x 10 = Testosterone, free (pg/mL)
  • Testosterone, free (pg/mL) / 10 = Testosterone, free (ng/dL)

2. Reference intervals for both free and total testosterone will be different.

Quest Diagnostics: Reference Intervals for Testosterone, Total (ng/dL)

Age

0-1 day

1-10 days

11-30 days

31 days – 2 months

3-4 months

5-6 months

7-11 months

12 months – 5 years

6-7 years

8-10 years

11 years

12-13 years

14-17 years

> 17 years

Male

17-61

<188

Not given

72-344

<202

<60

<17

<6

<26

<43

<261

<421

<1001

250-1100

Female

16-44

<25

Not given

<18

<13

<14

<12

<9

<21

<36

<41

<41

<41

2-45

Quest Diagnostics: Reference Intervals for Testosterone, Free (pg/mL)

Age

0-4 years

5-9 years

10-13 years

14-17 years

18-69 years

70-89 years

>89 years

Male

Not given

<5.4

0.7-52.0

18.0-111.0

35.0-155.0

30.0-135.0

Not given

Female

Not given

0.2-5.0

0.1-7.4

0.5-3.9

0.1-6.4

0.2-3.7

Not given

Specimen Requirements

Specimen Type
Serum

Collection Container
Red BD Hemogard™ Serum Tube (No Additive)

Volume
1.8 mL

Minimum Volume
0.9 mL

Do not draw serum gel tubes for this test.

Turnaround Time

Turnaround Time
Turnaround time for samples sent to the temporary performing laboratory (Quest Diagnostics) is estimated at 10 to 14 days.

TFTEST samples collected prior to October 25 will be resulted from the current reference laboratory (Mayo Medical Laboratories) but will have a delayed turnaround time of approximately 14 days.