TSH Levels and Other Health Conditions: Medical Journals

Purpose of this compilation

To show that using only the TSH (thyroid stimulating hormone) level as a diagnostic and assessment tool for hypothyroidism is inadequate because this test often fails to identify hypothyroidism. In addition, conditions such as depression, heart disease, and high cholesterol may develop as a result of untreated hypothyroidism, but not be identified as such because the TSH level can remain in the reference range.

See also the links in the right column as well as in our T3 References and Desiccated Thyroid References sections.

A. Depression
B. Heart disease
C. High cholesterol

A. Depression

1. "Exaggerated TSH Responses to TRH in Depressed Patients With 'Normal' Baseline TSH" (Canada, 1997)

Subtle thyroid underfunction may be contributing to depression in some patients with TSH in the upper half of the range usually considered normal.

2. "Thyroid hormone levels before unsuccessful antidepressant therapy are associated with later response to T3 augmentation" (Canada, 1997)

While all measures of thyroid function were within the euthyroid range, eventual T3 augmentation responders were found to have, prior to any antidepressant treatment, lower levels of TSH and higher levels of thyroxine (T4) and free thyroxine index (FTI) than non-responders.

3. "Thyroid hormone concentrations in depressed and nondepressed adolescents: group differences and behavioral relations" (US, 1996)

The sample included 21 depressed adolescents and 20 matched control adolescents. Blood was drawn to measure thyroid-stimulating hormone (TSH), free thyroxine (FT4), thyroxine (T4), and triiodothyronine (T3)....Paired analysis revealed there were no significant group or gender differences or group by gender interactions for TSH, T4, or T3. For FT4, however, there were significant group differences (p = .008) showing lower concentrations in depressed adolescents than control subjects, suggesting that the former might be functionally hypothyroid. Although there were no significant correlations of TSH with any of the psychological measures obtained, in the depressed group correlations were negative (although not always significant) with FT4 and total behavior problems...as well as with symptom scores....Higher numbers of symptom scores of OC and AD were related to lower concentrations of FT4.

4. "[Depressions resistant to tricyclic antidepressive treatment and hypothyroidism]" [article in French; abstract in English] (France, 1987)

The relationship between thyroid disorders and depression is well known....[including] the finding of slight thyroid dysfunction (increased TSH response after injection of TRH) in a patient with depression. The frequency of the association of hypothyroidism and resistant depression underlines the need to perform thyroid function tests in all depressed patients who do not respond normally to appropriate antidepressor therapy.

5. "Hypothyroidism and depression. Evidence from complete thyroid function evaluation." (1981)

These results suggest that a significant proportion of patients with depression and anergia may have early hypothyroidism, the cases of about half of which are detected only by thyrotropin-releasing hormone (TRH) testing. Because hypothyroidism can produce signs and symptoms of depression and can coexist as a second illness in depressed patients, patients with early hypothyroidism may be candidates for thyroid replacement therapy.

B. Heart disease

1. "Risk factors for cardiovascular disease in women with subclinical hypothyroidism" (Israel, 2002)

SH [subclinical hypothyroidism] was defined as an elevated thyrotropin (TSH) (>4.5 mU/L) and normal free thyroxine (FT4) level (8.7-22.6 nmol/L)....the percentage of patients with SH having hypertension (20%), hypertriglyceridemia (26.9%), elevated TC/HDL-C (11.5%), and LDL-C/HDL-C (4%) ratios were higher than the percentages in controls.

2. "Subclinical hypothyroidism is an independent risk factor for atherosclerosis and hyocardial infarction in elderly women: the Rotterdam study" (Netherlands, 2000)

Subclinical hypothyroidism was defined as an elevated thyroid-stimulating hormone level (>4.0 mU/L) and a normal serum free thyroxine level (11 to 25 pmol/L [0.9 to 1.9 ng/dL])....

Conclusion: Subclinical hypothyroidism is a strong indicator of risk for atherosclerosis and myocardial infarction in elderly women.

3. "Borderline low thyroid function and thyroid autoimmunity. Risk factors for coronary heart disease?" (1981)

Men and women with a thyroid stimulating hormone of 4.0 mU/l or over had a higher prevalence of coronary heart disease than did age-matched controls, and this difference was significant in women....Women with thyroid antibodies had a slightly higher prevalence of coronary heart disease despite the unexpected finding of a lower serum cholesterol. The data point to an association between borderline thyroid function and autoimmunity and coronary heart disease which is not mediated through a raised serum cholesterol.

C. High cholesterol

"High serum cholesterol levels in persons with 'high-normal' TSH levels: should one extend the definition of subclinical hypothyroidism?" (Greece, 1998)

Subjects with high-normal TSH levels [2.0-4.0 µU/ml] combined with ThAabs [thyroid autoantibodies] may, in fact, have subclinical hypothyroidism presenting with elevated cholesterol levels. It is possible that these patients might benefit from thyroxine administration.