Blood Test Information

TSH Blood Spot

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Test Code: BST

Special instructions
Minimum of two 8mm blood spots on bloodspot (Guthrie) card. Clearly mark for 'bloodspot TSH' on card.

Sent away to Southmead Hospital
Contact Laboratory before requesting

Reference range
Reference range <2.2 mU/L. Bloodspot is approximately 50% less than serum TSH.

Units
mU/L

Linked to
TSH

Turnaround Time
14 days

Department: Biochemistry

Clinical Application
Monitoring patients with Down syndrome or needle-phobia, to screen for primary hypothyroidism or detect under replacement with thyroxine. Limited to TSH measurement. Will not detect pituitary dysfunction and is not precise at low levels of TSH. Always confirm diagnosis with full venous thyroid profile if results fall outside of reference range.

Updated April 2024