It Might Be Your Thyroid

regnancy and childbirth change our lives in many ways. Some of changes aren't surprising--sleep deprivation, lack of time to do some things we used to enjoy, and that new tummy bulge that makes getting into pre-pregnancy clothes an acrobatic exercise. But about seven percent of all mothers also experience postpartum thyroid gland changes that affect their quality of life in unforseen ways.

The thyroid is a small gland located at the base of the neck. It produces hormones that regulate energy use throughout the body. When the thyroid stops functioning properly, widespread metabolic changes occur, causing many physical and emotional symptoms. These symptoms may be overlooked by tired new mothers, and not all doctors know that postpartum women are at risk for thyroid disorders.

When the thyroid becomes inflamed (thyroiditis), hormones normally stored in the gland are released in bulk into the bloodstream. Some women are particularly susceptible to thyroiditis after childbirth, possibly because of immune system adjustments that occur after delivery. Excess thyroid hormones send the metabolism into high gear, causing mental symptoms such as difficulty concentrating and anxiety, and physical symptoms including tremors, rapid heartbeat, a feeling of warmth, muscle weakness, and weight loss.
Hyperthyroidism is most common in the first few weeks after delivery, and usually resolves without treatment. Unfortunately, the inflamed thyroid sometimes becomes so damaged that it can't produce enough thyroid hormone, and the patient becomes hypothyroid.

An underactive thyroid produces too little thyroid hormone, which slows down the metabolism. Symptoms of hypothyroidism include fatigue, weakness, weight gain, constipation, cold intolerance, heavy menstrual periods, and muscle cramps. Memory impairment and depression can occur. Although this condition is usually temporary after childbirth, about 25% of women with postpartum hypothyroidism will need treatment for the rest of their lives.

The American Association of Clinical Endocrinologists recommends that women who suspect they have postpartum thyroiditis perform a simple physical check of their thyroid. Dubbed the Thyroid Neck Check, this simple test for thyroid inflammation is done using a mirror and a glass of water.
Although a very enlarged thyroid is easy to see, blood tests are also normally needed to detect thyroid disease. The thyroid actually produces two hormones, thyroxine (T4) and triiodothyronine (T3). T4 is the major thyroid hormone, and it is converted to T3 by many body tissues. Most lab tests for postpartum thyroid disease measure T4 levels. It's also common to test for blood levels of the pituitary hormone TSH, which helps regulate T4 production.
Thyroid disease can also be identified using additional tests for antibodies to thyroid hormones. However, thyroid disease has several causes, and other illnesses can affect the thyroid hormone production, so it's not always easy to positively identify specific thyroid problems using these tests. But it's important to pinpoint the exact problem, since different thyroid diseases require different treatments.

Some women develop Graves' disease after delivery. Graves' is an autoimmune disorder in which the patient produces antibodies that overstimulate the thyroid. Blood tests for T4 and TSH, and the use of a radioactive iodine uptake test help distinguish postpartum thyroiditis from Graves' disease. A thyroid damaged by postpartum thyroid disease takes up little radioactive iodine, while Graves' disease causes the thyroid to absorb high levels of iodine. Since radioactive iodine is secreted in breast milk, a mother should not nurse for three to five days after taking this test.

Hyperthyroidism in postpartum women is often unnoticed by the woman or her doctor, and usually corrects itself in a few months without treatment. If a woman develops Graves' disease, though, her thyroid hormone levels need to be controlled. Radioactive iodine therapy, the most common treatment in the US, is not safe for breastfeeding mothers or pregnant women. Drug therapy with beta-adrenergic blockers (propranolol, nadolol) or calcium channel blockers (diltiazem) may alleviate the symptoms of hyperthyroidism. In rare cases, surgery may be used to remove tissue from a very enlarged thyroid.

Hypothyroidism is treated with drugs that replace thyroid hormones. Since the thyroid hormone T4 is converted in the body to T3, most doctors prescribe T4 replacement only, using levoxythyroxine (Synthroid). This drug is considered extremely safe, even for pregnant and nursing women. It may take time to work out the correct dosage, but the results can seem miraculous to patients.

The February 11 issue of the New England Journal of Medicine (Bunevicius et al, 340:424, 1999) describes a small study in which both T4 and T3 were given to hypothyroid patients. This study examined both physical and emotional symptoms, and found that some patients feel better when they receive both T3 and T4, instead of just T4. Patients in this study received amounts of T4 and T3 similar to the amounts produced by a normal thyroid. In contrast, T4 replacement therapy usually requires a higher dosage of T4 than the normal thyroid makes. These findings are preliminary, but will certainly be of interest to patients who do not feel their best after treatment with T4 alone.

Screening for thyroid disease isn't recommended for the general population, or for all women who have just given birth. However, women who feel bad several weeks after childbirth and have some of the symptoms described here should be tested for thyroid disorders. Treatment is usually simple, and the results of treatment are so dramatic that no one should suffer needlessly from thyroid disease.

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Kate Traynor is a fabulous medical babe writer, mom of two boys and friend of Lynn's. © 1999-2005 Kate Traynor, used by permission.