HDL-Cholesterol in Human Serum with Roche c502

Detection of Free Thyroxine in Human Serum with Roche e801

Test Name: Immunoassay for the in vitro quantitative determination of free thyroxine (FT4) in human serum and plasma.
Method Name: In the Elecsys FT4 II assay a T4 specific antibody labeled with a ruthenium complex is used to determine the free thyroxine concentration.
Results: Technical Range: 0.101-7.77 ng/dL
Reportable Range: 0.36-6.7 ng/dL
Reference Ranges: 0-23 Months 0.88-1.48 ng/dL
2-12 Years 0.81-1.35 ng/dL
13-20 Years 0.78-1.33 ng/dL
≥ 21 Years 0.80-1.50 ng/dL
    Clinical Significance:     Thyroxine (T4) is the main thyroid hormone secreted into the bloodstream by the thyroid gland. Together with triiodothyronine (T3) it plays a vital role in regulating the body’s metabolic rate, influences the cardiovascular system, growth, and bone metabolism, and is important for normal development of gonadal functions and nervous system.

T4 circulates in the bloodstream as an equilibrium mixture of free and serum bound hormone. Free T4 (fT4) is the unbound and biologically active form, which represents only 0.03 % of the total T4. The remaining T4 is inactive and bound to serum proteins such as thyroxine binding globulin, TBG (75 %), pre-albumin (15 %), and albumin (10 %).

The determination of free T4 has the advantage of being independent of changes in the concentrations and binding properties of these binding proteins; additional determination of a binding parameter (T uptake, TBG) is therefore unnecessary. Therefore free T4 is a useful tool in clinical routine diagnostics for the assessment of the thyroid status. It should be measured together with TSH if thyroid disorders are suspected and is also suitable for monitoring thyrosuppressive therapy.

A variety of methods are available for estimating the free thyroid hormone levels. The direct measurement of fT4 and fT3 via equilibrium dialysis or ultrafiltration is mainly used as a reference method for standardizing, the immunological procedures generally used for routine diagnostic purposes.

Submission Criteria: For specimen collection and preparation, only use suitable tubes or collection containers. Only the specimens listed below were tested and found acceptable.
Plasma: Li-heparin and K2-EDTA plasma
Do not use fluoride plasma

The sample types listed were tested with a selection of sample collection tubes that were commercially available at the time of testing, therefore not all available tubes of all manufacturers were tested. Sample collection systems from various manufacturers may contain differing materials which could affect the test results in some cases.  When processing samples in primary tubes (sample collection systems), follow the instructions of the tube manufacturer.

Storage and Stability:    30 days at -20°C
7 days at 2-8°C
5 days at 20-25 °C
Freeze only once.

Rejection Criteria: Rejection criteria include but are not limited to:
1. Specimens containing fibrin or clots.
2. Excessive platelet clumping
3. Leaking specimens
4. Substandard mixing or collection
5. Expired or improperly stored collection tubes.
6. Improperly filled tubes based on collection tube manufacturer’s guidelines.
7. Contaminated specimens (IV fluid, foreign particles, etc.)
8. Specimens not analyzed within the appropriate time frame.
9. Samples not shipped at appropriate temperature.
10. Samples without 2 proper identifiers or samples having identifiers that do not match the electronic or paper lab requisition.
Authorization: Diagnostic testing can only be performed with approval from an authorized provider/agency.
Turn Around Time: 1 day.