Abnormal total T4 levels can have various causes, ranging in severity from 'troubling' to 'life-threatening'. Finding the true cause means ruling out or confirming each possibility – in other words, diagnosis.
Diagnosis is usually a complex process due to the sheer number of possible causes and related symptoms. In order to diagnose abnormal total T4 levels, we could:
|Cirrhosis Of The Liver||5%||Ruled out|
|Megaloblastic Anemia||3%||Ruled out|
|Iodine Need||3%||Ruled out|
|Autoimmune Tendency||0%||Ruled out|
T4 (Total). Unit: ug/dL [nmol/L]
Possible responses:→ Don't know
→ Under 4.5  (low)
→ 4.5 to 5.9 [58-76] (low - normal)
→ 6.0 to 11.5 [77-148] (normal)
→ Over 11.5  (elevated)
When TSH and Total T4 are both low, a poorly-functioning pituitary gland is suspected.
Hypothyroidism also suggests the following possibilities:
There are a limited number of studies that suggest low copper levels may reduce thyroid function. In cases where hypothyroidism is not responding properly to medication, make sure that copper levels are normal.
Though apparently vague and non-specific, most of the symptoms of fluoride toxicity point towards some kind of profound metabolic dysfunction, and are strikingly similar to the symptoms of hypothyroidism.
Low iodine intake can cause hypothyroidism in adults.
Pernicious anemia is associated with other autoimmune conditions such as Hashimoto's disease, a form of hypothyroidism.
Progesterone increases sensitivity of estrogen receptors, and can therefore redirect estrogen activity and inhibit many of unopposed estrogen's undesirable side-effects, which includes interference with thyroid hormone activity.