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11. Euthyroid Sick Syndrome and Low T3 Syndrome

Euthyroid sick syndrome

“Euthyroid,” simply means normal thyroid. Often, severely sick people develop hypothyroidism, despite there being nothing actually wrong with the thyroid gland. This is called Euthyroid Sick Syndrome. [60]

Medical texts cite several severe conditions that cause euthyroid sick syndrome: fasting, starvation, protein-calorie malnutrition, general surgical trauma, myocardial infarction [heart attack], chronic renal failure [kidney failure], diabetic keto-acidosis, anorexia nervosa, cirrhosis [liver failure], thermal injury and sepsis [infection in the blood]. [61]

Euthyroid sick syndrome is not a disease. It is a self protective mechanism.

Stress, such as a systemic non-thyroidal illness...or caloric deprivation, in euthyroid humans, produces characteristic alterations in serum thyroid hormones indices, which, in certain instances, may minimize the catabolic impact of these events. [62]

In lay language the above means: stress on the body such as an illness, or not eating enough calories, will cause the body to lower levels of thyroid hormone, in order to decreased metabolic rate and hence lessen the damage that these stressors have on the body.

The article continues: "It is estimated that over 70% of hospitalized patients display changes in the thyroid hormone indices, without having any demonstrable underlying thyroid disease."

Low T3 Syndrome

Two triggers of Euthyroid Sick Syndrome are:

However, the term euthyroid sick syndrome is usually reserved for severely ill patients. The phrase Low T3 Syndrome best describes people who have low thyroid hormone due to causes such as:

Getting back to the thyroid family chart, much of Low T3 syndrome is caused by either low TSH, or blocks in the conversion of T4 into T3.

Low thyroid chart, T3 syndrome

Thyroid Lab commonly seen with Low TSH subclinical hypothyroidism:

T4 is normal or high
TSH is normal of slightly low
T3 is low
Reverse T3 is sometimes high [63]