Normal Thyroid Function
Your TSH of 1.3 mIU/L and T4 of 1.93 indicate normal thyroid function—no treatment or further testing is needed unless you develop symptoms. 1
Understanding Your Results
A TSH of 1.3 mIU/L falls well within the normal reference range (typically 0.4-4.5 mIU/L), indicating your pituitary gland is appropriately regulating thyroid hormone production 1, 2
Your T4 level of 1.93 (assuming units of ng/dL, approximately 25 nmol/L) is also within normal limits, confirming adequate thyroid hormone production 1
These values together definitively exclude both hypothyroidism and hyperthyroidism 1, 3
Clinical Significance
TSH is the most sensitive test for detecting thyroid dysfunction, with sensitivity above 98% and specificity greater than 92% 2, 4
The combination of normal TSH and normal T4 indicates you are biochemically euthyroid (normal thyroid function) 1, 3
Your TSH level is actually in the optimal mid-range, which is associated with the lowest risk of progression to thyroid dysfunction 2
What These Results Rule Out
Subclinical hypothyroidism is defined as TSH >4.5 mIU/L with normal T4—your TSH of 1.3 is far below this threshold 1, 2
Overt hypothyroidism requires both elevated TSH and low T4—you have neither 1
Subclinical hyperthyroidism is defined as TSH <0.4 mIU/L with normal T4—your TSH of 1.3 is above this threshold 1, 3
Overt hyperthyroidism requires suppressed TSH with elevated T4 or T3—you have neither 1
No Action Required
No treatment is indicated, as both values are solidly within normal ranges 2, 3
Routine screening is not recommended for asymptomatic individuals with normal thyroid function 1
You do not need repeat testing unless you develop symptoms suggestive of thyroid dysfunction (unexplained fatigue, weight changes, temperature intolerance, hair loss, or heart palpitations) 1, 2
Important Context
Laboratory reference ranges are based on the statistical distribution across the general population, typically using the 2.5th to 97.5th percentile 1
Your results indicate your thyroid-pituitary axis is functioning normally with appropriate feedback regulation 4
Even if you had borderline abnormal results, 30-60% of mildly elevated TSH levels normalize on repeat testing, representing transient variations rather than true thyroid disease 2