Subclinical Hypothyroidism: A Review of Neuropsychiatric Aspects

Haggerty, John J.; Garbutt, James C.; Evans, Dwight L.; Golden, Robert N.; Pedersen, Cort A.; Simon, Jeffrey S.; Nemeroff, Charles B.

doi:10.2190/adly-1uu0-1a8l-hpxy

Cited by 118 publications

(59 citation statements)

References 54 publications

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“…44 A recent study showed no association with anxiety, depression, or cognitive dysfunction. 25 Nonetheless, it is still reasonable to have a low threshold for therapy for SCH in patients with depression, bipolar disorder, and cognitive dysfunction.…”

Section: Psychiatric and Cognitive Dysfunctionmentioning

confidence: 95%

Subclinical Hypothyroidism: An Update for Primary Care Physicians

Fatourechi

2009

Mayo Clinic Proceedings

294

186

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Subclinical hypothyroidism (SCH), also called mild thyroid failure, is diagnosed when peripheral thyroid hormone levels are within normal reference laboratory range but serum thyroid-stimulating hormone (TSH) levels are mildly elevated. This condition occurs in 3% to 8% of the general population. It is more common in women than men, and its prevalence increases with age. Of patients with SCH, 80% have a serum TSH of less than 10 mIU/L. The most important implication of SCH is high likelihood of progression to clinical hypothyroidism. The possibility that it is a cardiovascular risk factor has been a subject of debate. Large-scale randomized studies are needed for evidence-based recommendations regarding screening for mild thyroid failure and levothyroxine therapy for this condition. Currently, the practical approach is routine levothyroxine therapy for persons with a persistent serum TSH of more than 10.0 mIU/L and individualized therapy for those with a TSH of less than 10.0 mIU/L. © 2009 Mayo Foundation for Medical Education and ResearchOn completion of this article you should be able to: (1) S ubclinical hypothyroidism (SCH) is defined as a serum thyroid-stimulating hormone (TSH) level above the upper limit of normal despite normal levels of serum free thyroxine. 1 Serum TSH has a log-linear relationship with circulating thyroid hormone levels (a 2-fold change in free thyroxine will produce a 100-fold change in TSH). Thus, serum TSH measurement is the necessary test for diagnosis of mild thyroid failure when the peripheral thyroid hormone levels are within normal laboratory range. 1 The individual range for peripheral thyroid hormones is narrower than the population reference laboratory range; therefore, a slight reduction within the normal range will result in elevation of serum TSH above the normal range.Subclinical hypothyroidism or mild thyroid failure is a common problem, with a prevalence of 3% to 8% in the population without known thyroid disease. 2,3 The prevalence increases with age and is higher in women. 2 After the sixth decade of life, the prevalence in men approaches that of women, with a combined prevalence of 10%. 2 Antithyroid antibodies can be detected in 80% of patients with SCH, and 80% of patients with SCH have a serum TSH of less than 10 mIU/L.Before diagnosis of SCH, other causes of an elevated TSH level, such as recovery from nonthyroidal illness, assay variability, presence of heterophile antibodies interfering with the TSH assay, and certain cases of central hypothyroidism with biologically inactive TSH and thyroid hormone resistance, should be excluded. However, the most common cause of elevated TSH is autoimmune thyroid disease. 1 Previous radioiodine therapy, thyroid surgery, and external radiation therapy can also result in mild thyroid failure. Transient SCH may occur after episodes of postpartum, silent, and granulomatous thyroiditis. 1,4 The clinical importance of and therapy for mild elevation of serum TSH (<10 mIU/L) 5 and the exact upper limit of normal for the serum TSH ...

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Section: Psychiatric and Cognitive Dysfunctionmentioning

confidence: 95%

Subclinical Hypothyroidism: An Update for Primary Care Physicians

Fatourechi

2009

Mayo Clinic Proceedings

294

186

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“…Subclinical or mild hypothyroidism is common in women and in the elderly and has been associated with alteration in the lipoprotein profile, such as increased cholesterol, and with increased incidence of depression by lowering of the threshold for the development of major depressive disorders (40) and other mood disorders (41,42). In addition, mild hypothyroidism has been linked with diminished response to standard psychiatric treatment and with cognitive dysfunction (41). A 0.26 ng/dL geometric mean difference in free T4 in women during the second trimester of pregnancy has been associated with an average 4-point IQ reduction in their children (0.97 ng/dL vs. 0.72 ng/dL; p < 0.001) (43).…”

Section: Borderline Hypo-and Hyperthyroidismmentioning

confidence: 99%

Significant effects of mild endogenous hormonal changes in humans: considerations for low-dose testing.

Brucker‐Davis

Thayer

Colborn

2001

Environ Health Perspect

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We review the significant and adverse health effects that can occur with relatively small endogenous hormonal changes in pubertal and adult humans. We discuss the effects of hormonal changes that occur within normal physiologic ranges--such as the rising levels of estrogen in peripuberty, which cause growth spurts at low levels and then the fusion of epiphyses at higher levels--and the hormonal variations during the menstrual cycle and their relation to genital phenotypic changes and intercurrent disease evolution. We turn next to adaptive changes in gonadal and other functions during aging, exercise, stress, starvation, and chronic diseases, which can serve as models for the effects of exogenous, hormonally active compounds. Then we review the states of borderline hormonal imbalances such as subclinical (having few or very mild symptoms, if any) hypothyroidism or hyperthyroidism, glucose intolerance, and other endocrine conditions. Finally, we review the deleterious systemic effects of gonadal imbalance. Information stemming from clinical observations leads to the concept of "no threshold" within the endocrine system and thus illustrates the importance of considering low-dose testing for chemicals that interfere with hormonal activity. We also urge attention to more sensitive, less visible end points such as osteoporosis, increased risk for cardiovascular disease, or cognitive changes.

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“…In adults, these states are reversible and psychological testing of hypothyroid patients has consistently revealed that intellectual impairment subsides with thyroxine treatment (2,3).…”

Section: Introductionmentioning

confidence: 99%

L-thyroxine treatment and neurotransmitter levels in the cerebrospinal fluid of hypothyroid patients: a pilot study

Sjöberg

Eriksson

Nordin

1998

European Journal of Endocrinology

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Monoamine precursors, neurotransmitters and their metabolites were studied in cerebrospinal fluid (CSF) obtained from nine newly diagnosed hypothyroid patients.Before treatment, the serum TSH correlated positively with the CSF concentrations of tyrosine and phenylalanine.During treatment, the levels of the precursors tryptophan, phenylalanine and tyrosine decreased significantly, as was also the case with dopamine and the noradrenaline metabolite 4-hydroxy-3-methoxyphenylglycol (HMPG), but not with serotonin, noradrenaline and the serotonin metabolite 5-hydroxyindoleacetic acid, nor the dopamine metabolites homovanilic acid and dihydroxyphenylacetic acid. The study provided some indication that the CSF levels of phenylalanine and tyrosine are related to thyroid function. Furthermore, we have found an indication that L-thyroxine treatment affects the CSF levels of the precursors as well as dopamine and HMPG. Our results support the notion that there is an interaction between thyroid function and CSF disposition of monoamine compounds.

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Subclinical Hypothyroidism: A Review of Neuropsychiatric Aspects

Cited by 118 publications

References 54 publications

Subclinical Hypothyroidism: An Update for Primary Care Physicians

Subclinical Hypothyroidism: An Update for Primary Care Physicians

Significant effects of mild endogenous hormonal changes in humans: considerations for low-dose testing.

L-thyroxine treatment and neurotransmitter levels in the cerebrospinal fluid of hypothyroid patients: a pilot study

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