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Clinical Chemistry and Hematology Laboratories

Endocrinology Proficiency Testing

Summary of endocrinology proficiency testing results (January 2001 - present) are available on line. Go to the Endocrinology Proficiency Test Data Base

The Endocrinology Proficiency Testing (PT) Program currently surveys 23 analytes including all 9 analytes (see the following table) listed in the Federal Register (Dept of Health and Human Services, Health Care Financing Administration. Clinical Laboratory Improvement Amendments of 1988;Final Rule. Fed. Reg. February 28, 1992;57:7001-7288). 

Sample source>: A series of 5 samples constituted with pooled normal human serum and analytes at clinically relevant concentrations are prepared for each PT event. The PT specimens are subsequently verified, sterile-filtered (0.22 µm pore size), aliquoted, stored frozen at -80°C and shipped in the frozen state. Three PT events are scheduled annually in January, May and September.

Sample quality and stability: No preservatives or stabilizers are added to the PT samples to eliminate the potential interference from the additives. Proficiency testing specimens are sterilized by micro-filtration to eliminate the microorganisms in the samples that may deteriorate the components of the sample. Unlike lyophilized specimens, serum-based aqueous samples are provided to avoid human error during sample reconstitution. Results from stability studies show samples are stable at room temperature for up to two days, at 4°C for at least 10 days and at -80°C for at least three months.

Target values and grading: Acceptable ranges are established using fixed criteria specified by CLIA '88 for the CMS-defined analytes and are listed below. 

Analyte	Acceptable Limit
Thyroxine (T4) *	Target value ± 20% or 1.0 µg/dL#
Free Thyroxine (FT4) *	Target value ± 3 SD
T3 Uptake *	Target value ± 3 SD
T-Uptake	Target value ± 3 SD
Tri-iodothyronine (T3) *	Target value ± 3 SD
Free T3	Target value ± 25% or 0.5 pg/mL#
Thyroid-stimulating hormone (TSH)*	Target value ± 3 SD
Vitamin B12	Target value ± 25%
Folic Acid	Target value ± 30% or 2.0 ng/mL#
Cortisol *	Target value ± 25%
Insulin	Target value ± 25% or 3.0 µU/mL#
Free Estriol	Target value ± 25% or 3.0 ng/mL#
Estradiol	Target value ± 25% or 30 pg/mL#
Testosterone	Target value ± 25% or 20 ng/dL#
Progesterone	Target value ± 25% or 1.0 ng/mL#
Dehydroepiandrosterone sulfate (DHEA-S)	Target value ± 25%
LH	Target value ± 25% or 1.5 mIU/mL#
FSH	Target value ± 25%
Prolactin	Target value ± 25% or 1.0 µg/L#
Intact Parathryin (PTH)	Target value ± 25% or 2 pg/mL#
Intact hCG *	Target value ± 3 SD
Total hCG *	Target value ± 3 SD
Qualitative hCG *	Positive/negative
* CMS (formerly HCFA) defined analytes and #Whichever is greater

Participant results falling within the acceptable limits are considered satisfactory performance (100%); results outside the limits are considered unsatisfactory performance (0%). A minimal score of 80% is considered satisfactory performance for an analyte and an overall proficiency test event. Laboratories that fail to demonstrate satisfactory performance (< 80%) for an analyte in two consecutive test events or two out of three events are required to perform corrective action and complete a remediation program for that analyte. Remediation programs are designed specifically for individual laboratory based upon the nature of the proficiency test failure.

All summary data from endocrinology proficiency tests (2001 - present) are available on line. Recent events will be available here prior to mailing results to participants. Go to the Endocrinology Proficiency Test Data Base