Thyroid Labs (TSH, T3, T4) on the NCLEX
TSH first-line, T4 and T3, subclinical disease.
Thyroid testing starts with TSH. NCLEX tests interpretation patterns.
TSH
Most sensitive screen. Normal 0.4-4.0. Elevated TSH = hypothyroidism (pituitary trying harder). Low TSH = hyperthyroidism.
T4 (thyroxine)
Free T4 is the active form. Confirms hypo or hyper after abnormal TSH.
T3 (triiodothyronine)
Mostly from peripheral T4 conversion. Useful in T3 toxicosis.
Subclinical disease
Abnormal TSH with normal T4. Treat if symptoms, pregnancy planning, or high TSH (>10).
Frequently asked
TSH for levothyroxine monitoring?
Yes. Check 6-8 weeks after dose change. Aim for normal TSH.
Pregnancy TSH target?
Trimester-specific reference ranges. Generally lower than non-pregnant.
Quick check
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