Clinical Significance
TSH, 4 Specimens - For differential diagnosis of primary, secondary, and tertiary hypothyroidism. Also useful in screening for hyperthyroidism. This assay allows adjustment of exogenous thyroxine dosage in hypothyroid patients and in patients on suppressive thyroxine therapy for thyroid neoplasia.

Preferred Specimen(s)
1 mL serum per specimen

Minimum Volume
0.7 mL per specimen

Transport Container
Serum Separator Tubes (SST®s)

Transport Temperature
Room temperature

Specimen Stability
Room temperature: 7 days
Refrigerated: 7 days
Frozen: 28 days
Reject Criteria
Plasma

Patient Preparation
Specimen collection after fluorescein dye angiography should be delayed for at least 3 days. For patients on hemodialysis, specimen collection should be delayed for 2 weeks. According to the assay manufacturer Siemens: "Samples containing fluorescein can produce falsely depressed values when tested with the Advia Centaur TSH3 Ultra assay. "

Methodology
Immunoassay (IA)

Reference Range(s)
1-2 Days    3.20-34.60 mIU/L
3-4 Days    0.70-15.40 mIU/L
5 Days-4 Weeks    1.70-9.10 mIU/L
1-11 Months    0.80-8.20 mIU/L
1-19 Years    0.50-4.30 mIU/L
≥20 Years    0.40-4.50 mIU/L
Pregnancy     
  First Trimester    0.26-2.66 mIU/L
  Second Trimester    0.55-2.73 mIU/L
  Third Trimester    0.43-2.91 mIU/L