Thyroid Function Test Interpretation
Your thyroid function tests show a completely normal thyroid status that requires no intervention. With a TSH of 1.79 mIU/L, total T4 of 11.1 µg/dL, and total T3 of 248 ng/dL, all values fall well within the normal reference ranges, indicating euthyroidism (normal thyroid function) 1, 2, 3.
Why These Results Are Normal
TSH of 1.79 mIU/L is optimal – this falls in the middle of the standard reference range (0.45–4.5 mIU/L), with the geometric mean for disease-free populations being 1.4 mIU/L 1, 3. Your value is essentially at the population average, representing ideal thyroid regulation.
Total T4 of 11.1 µg/dL is normal – typical reference ranges for total T4 are approximately 5–12 µg/dL, placing your result comfortably within normal limits 4, 5.
Total T3 of 248 ng/dL is normal – standard reference ranges for total T3 are approximately 80–200 ng/dL, though some laboratories extend the upper limit to 250 ng/dL 4, 5. Your value is at or just above the upper normal range but not clinically significant given the normal TSH.
Clinical Significance
The combination of normal TSH with normal T4 and T3 definitively excludes both overt and subclinical thyroid dysfunction 1, 2. TSH has 98% sensitivity and 92% specificity for detecting thyroid disease, making a normal result highly reliable for excluding dysfunction 2, 3.
When TSH is normal (0.45–4.5 mIU/L), the accuracy for confirming euthyroidism exceeds 99% 3.
TSH is the most sensitive early marker of thyroid gland failure, rising before T4 or T3 decline 2, 4. Your normal TSH confirms adequate thyroid hormone production.
The slightly elevated total T3 (if truly above range) is not clinically meaningful when TSH and T4 are normal, as TSH reflects the integrated thyroid hormone effect at the tissue level 4, 6.
What This Means for You
No treatment, monitoring, or further testing is needed 1, 2. Your thyroid gland is functioning normally, producing appropriate amounts of thyroid hormone, and your pituitary feedback mechanism is intact.
If you have symptoms such as fatigue, weight changes, or temperature intolerance, these are not due to thyroid dysfunction and require evaluation for other causes 1, 3.
Routine thyroid screening is not recommended for asymptomatic individuals without risk factors 1, 2.
When to Recheck
Thyroid function testing should only be repeated if you develop symptoms suggestive of thyroid disease (unexplained fatigue, significant weight changes, palpitations, heat/cold intolerance) or if new risk factors emerge (starting certain medications, developing other autoimmune conditions, pregnancy) 1, 2.
TSH values can naturally vary by up to 40–50% due to pulsatile secretion, time of day, and physiological factors 1. Minor fluctuations within the normal range do not indicate disease.
Approximately 12% of individuals over age 80 have TSH >4.5 mIU/L without thyroid disease, reflecting age-related reference range shifts 1. Your current normal values require no age adjustment.