Your Total T4 Level

What Causes Abnormal Total T4 Levels?

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:
  • Research the topic
  • Find a doctor with the time
  • Use a diagnostic computer system.
The process is the same, whichever method is used.

Step 1: List all Possible Causes

We begin by identifying the disease conditions which have "abnormal total T4 levels" as a symptom.  Here are eight of many possibilities (more below):
  • Hypopituitarism
  • Low Progesterone
  • Hyperthyroidism
  • Cirrhosis Of The Liver
  • Hypothyroidism
  • Iodine Need
  • Fluorosis*
  • Copper Deficiency
* symptoms can be very similar

Step 2: Build a Symptom Checklist

We then identify all possible symptoms and risk factors of each possible cause, and check the ones that apply:
much tooth staining or pitting
moderate unexplained weight gain
major joint pain/swelling/stiffness
difficulty falling asleep
weak sexual desire
normal TSH
frequent stools
having watery stools
difficulty losing weight
bulging eyes from hyperthyroidism
low HDL cholesterol level
low progesterone level
... and more than 110 others

Step 3: Rule Out or Confirm each Possible Cause

A differential diagnosis of your symptoms and risk factors finds the likely cause of abnormal total T4 levels:
Cause Probability Status
Low Progesterone 99% Confirm
Iodine Need 12% Unlikely
Hyperthyroidism 13% Unlikely
Hypothyroidism 3% Ruled out
Copper Deficiency 1% Ruled out
Fluorosis** 0% Ruled out
Cirrhosis Of The Liver 0% Ruled out
Hypopituitarism 0% Ruled out
* This is a simple example to illustrate the process
** Symptoms can be very similar

Arriving at a Correct Diagnosis

The Analyst™ is our online diagnosis tool that learns all about you through a straightforward process of multi-level questioning, providing diagnosis at the end.

If you indicate having had recent lab tests, The Analyst™ will ask further questions including this one:
T4 (Total). Unit: ug/dL [nmol/L]
Possible responses:
→ Don't know
→ Under 4.5 [58] (low)
→ 4.5 to 5.9 [58-76] (low - normal)
→ 6.0 to 11.5 [77-148] (normal)
→ Over 11.5 [148] (elevated)
Based on your response to this question, which may indicate having low TT4 level, having low-normal TT4 level, having normal TT4 level or having elevated TT4 level, The Analyst™ will consider possibilities such as:
Hypopituitarism
When TSH and Total T4 are both low, a poorly-functioning pituitary gland is suspected.
Progesterone Low or Estrogen Dominance
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.
Iodine Requirement
Low iodine intake can cause hypothyroidism in adults.
Megaloblastic Anemia / Pernicious Anemia
Pernicious anemia is associated with other autoimmune conditions such as Hashimoto's disease, a form of hypothyroidism.
Copper Deficiency
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.
Fluoride Toxicity
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.

Related Questions

Hormone-Related Lab Values