Neuropsychiatric Involvement in Subclinical Hypothyroidism

Sub-clinical hypothyroidism (SCH), defined by an increase in thyroid stimulating hormone (TSH) with a normal free total thyroxin (fT4) fraction, is the most frequent thyroid dysfunction. Its average prevalence is estimated at 4-10.5%, but can reach 15% in women over 50 years, and up to 20% in elderly beyond 60 years. Clinical manifestations during this endocrinopathy are not unanimous. Neuropsychiatric manifestations associated to SCH are far from uncommon; they significantly alter the quality of life of patients, may be the first signs revealing the disease, and present a real challenge for clinicians. Their better knowledge is very useful for any health professional given the high frequency of this disease in the general population. The objective of this review is to familiarize health professionals, in particular primary care physicians, with the different patterns of neuropsychiatric involvement of SCH.

Keywords: Sub-clinical hypothyroidism; Central nervous system; Peripheral nervous system; Neuropsychiatric involvement; Neuropathy; Hypothyroidism