| Laboratory: | Clinical Biochemistry (AUTOMATED) | ||||||||||||||||||||||||
| Test Name: |
THYROXINE, FREE (FREE T4) - (P)
Test Code:
FT4
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| Clinical Information: |
Description: FT4 is available as a component of the Thyroid Reflex Testing protocol when TSH is <0.4 mU/L or >4.2 mU/L.
Ordering FT4 and/or FT3 outside of reflex testing is restricted. 1) FT4 can be ordered using “General Endocrinology Requisition” and indicating reason for ordering OR 2) FT4 and FT3 can be ordered using “Specialized Endocrinology Requisition ” by pre-approved physicians only. · With known or suspected pituitary/hypothalamic disease · Treated for primary hyperthyroidism, severe hyperthyroidism (thyroid storm), or severe hypothyroidism (myxedema coma) · Known resistance to thyroid hormones · Treated with lithium carbonate, an anticonvulsant, or amiodarone · Pregnancy · Children under 2 years of age |
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| Collection Devices: |
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| Specimen Required: |
Plasma: 2.0 mL
Specimen Stability Refrigerated: 7 days Frozen: 1 month, freeze only once |
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| Referral: |
Shipping & Storage: Samples must be transferred to an aliquot tube and stored/shipped
· Refrigerated if off-site testing to be performed within 48 hours of collection · Frozen if testing to be performed after 48 hours See #110-10-05 Serum / Plasma Separation Procedure & Transport |
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| Requisition: | |||||||||||||||||||||||||
| Reference Values: |
Reference Intervals:
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| Availability: |
Daily
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| More Information: |