What does low TSH but normal T3 and T4 mean?

A low TSH with normal free T4 and T3 levels is consistent with subclinical hyperthyroidism. Some patients with nodular goiter and Graves’ disease, particularly early in the disease course, will have predominant elevations in T3 due to increased conversion of T4 to T3 and a disproportionate increase in T3 secretion.

What does it mean if your TSH is low and your T4 is high?

A low TSH and high T4 generally means an overactive thyroid. A high TSH and low T4 means an underactive thyroid. A low TSH and low T4 mean low thyroid function because of another problem, such as with the pituitary gland or hypothalamus of the brain.

What does it mean if your TSH is high but your T3 and T4 are normal?

Normally, low levels (less than 5 units) of TSH are sufficient to keep the normal thyroid gland functioning properly. When the thyroid gland becomes inefficient such as in early hypothyroidism, the TSH becomes elevated even though the T4 and T3 may still be within the “normal” range.

Is TSH more important than T3 and T4?

Across many clinical studies it seems clear that the physiologic effects of low or high thyroid function correlate much more strongly to free T4 and free T3 levels than to TSH levels. In fact, correcting for changes in T4 and T3 levels there appeared to be no correlation between TSH level and body function.

What diseases can mimic hypothyroidism?


  • Bronchitis.
  • Bulimia Nervosa.
  • Chronic Obstructive Pulmonary Disease.
  • Congestive Heart Failure.
  • Depression.
  • Menopause.
  • Preeclampsia.
  • What causes low TSH levels?

    Hashimoto’s Disease. This is the most common reason that Americans have low thyroid levels.

  • Surgery on the Thyroid Gland.
  • Treatment With Radiation.
  • Thyroid Swelling.
  • Medicines.
  • Too Little or Too Much Iodine.
  • Hypothyroidism at Birth.
  • Damage to the Pituitary Gland.
  • What do high and low TSH levels mean?

    Graves’ disease.

  • Plummer’s disease.
  • Nodules or cysts in the thyroid gland.
  • Excess iodine.
  • Inflammation of the thyroid (thyroiditis) If your TSH levels are low,it could mean that you have a condition called thyroiditis.
  • Tumors of ovaries or testes.
  • Benign tumors of the thyroid gland or pituitary gland.
  • Drug-induced thyroid disorders.
  • Thyroid cancer.
  • What is considered a low TSH level?

    What is considered a low TSH level? A TSH level higher than 5.0 usually indicates an underactive thyroid (hypothyroidism) and a TSH level lower than 0.4 indicates the presence of excessive thyroid hormone and overactive thyroid (hyperthyroidism). The normal range may vary slightly in different laboratories.

    How would you address normal TSH but low T4?

    🧠 In fact, it would become unclear whether your pituitary is actually making the right signal because if your T4 and your T3 are low, your TSH should be high because your pituitary should be saying, “wait a second, T4 and T3 are low, so I need to make more of the message, TSH, to tell the thyroid gland to kick into gear.”