Subclinical Hypothyroidism Subclinical hypothyroidism, also known as mild hypothyroidism, is usually asymptomatic or if it does manifest itself, it may present with vague symptoms that could be attributed to other causes.
Patients with subclinical hypothyroidism have elevated serum levels of the thyroid-stimulating hormone while maintaining normal levels of thyroxine and triiodothyronine and may occur in the presence or absence of thyroid antibodies.
A common cause for subclinical hypothyroidism in areas with sufficient iodine sources is Hashimoto's disease.
In Hashimoto's disease, a person's own immune system generates antibodies, now called autoantibodies, that target the thyroid gland and impair its function.
Patients with subclinical hypothyroidism also run the risk of developing overt hypothyroidism.
Several signs of subclinical hypothyroidism include fatigue, constipation, weight gain, intolerance to cold, dry skin, menometorrhagia and infertility, decreased concentration and memory, and coarseness or loss of hair.
Unfortunately, these symptoms may be overlooked by the patient himself and the hormone deficiency remains uncorrected until its more overt characteristics are manifested.
Adverse Outcomes of Subclinical Hypothyroidism on Pregnancy A study was conducted to determine the presence of antithyroid antibodies in women enrolled in an in vitro fertilization program in comparison to a control group of women who have never been pregnant.
All women in the control group with normal thyroid function and have no history of autoimmune disease or miscarriage.
The findings suggested that the presence of antithyroid antibodies may have a hand in unexplained and mechanical infertility.
In another study, it was observed that the prevalence of spontaneous miscarriages is higher in women found to have antithyroid antibodies in comparison to women who tested negative for antithyroid antibodies.
This study suggested that the presence of said antibodies in the first trimester of the pregnancy played a significant role in the increased rate of spontaneous abortion.
Women with overt and subclinical hypothyroidism were also found to have a significantly higher risk of developing pre-eclampsia, eclampsia, and pregnancy-induced hypertension.
There was also a prevalence of gestational hypertension in mothers who were hypothyroid at delivery.
Thyroid replacement therapy may help prevent gestational hypertension and its sequelae.
Women with overt hypothyroidism were also most likely to deliver babies with low birth weight in comparison to the general population.
Women with subclinical hypothyroidism were less likely than those with overt hypothyroidism to give birth to low birth weight babies but still more likely to do so than the general population.
Placental abruption and preterm birth was also found to be of higher prevalence in women with subclinical hypothyroidism than in those with normal thyroid function.
In comparison to euthyroid mothers, there was a three-fold increase in the incidence of placental abruption, almost two-fold increase in preterm delivery, two-fold increase in neonate intensive care admission, and incidence of respiratory distress syndrome in the neonates birthed by subclinically hypothyroid mothers.
Screening and Treatment It is of utmost important for expecting mothers to be screened for subclinical hypothyroidism in order for them to enjoy a safe and normal pregnancy.
The dire consequences discussed above are not only physically traumatic for both the mother and the child but may be emotionally tragic for the whole family.
Prompt detection of subclinical hypothyroidism could determine the difference between a life and a loss.