Thyroid Disease in Pregnancy

Thyroid disease is the 2nd most common endocrine disorder that affects women of childbearing age. Hyperthyroidism occurs in 0.2% of pregnancies. Hypothyroidism occurs in 2.5% of pregnancies. Postpartum thyroid disease occurs in 5-10% of women after delivery who don’t have history of thyroid disease. 25% of women with Type 1 DM develop postpartum thyroid dysfunction. Incidence of thyroid cancer in pregnancy is 1 per 1000. Malignancy is found in up to 5-40% of thyroid nodules discovered during pregnancy.

Radioactive Iodine Therapy

Adequate radioactive iodine treatment will result in complete or near complete elimination of the thyroid gland (this is what we want it to do). The treatment usually takes approximately 3 months to be completely effective. The treatment is effective in 90% of patients. In 10% of patients, overproduction of thyroid hormone may persist. For these patients, a second treatment with radioactive iodine may be needed in 6-9 months.

Before Thyroid Surgery

BEFORE YOU HAVE ANY NECK SURGERY FOR THYROID:

If you are discovered to have a thyroid nodule, 1st remember the risk of cancer is less than 10%.

The proper assessment to rule out cancer, involves fine needle biopsy (FNA) with ultrasound guidance. Prior to any thyroid surgery, a proper neck assessment with ultrasound, to determine lymph node involvement, is the standard of care. Too often patients are taken to surgery, even for something determined to be benign, but are found to have incidental cancer. A proper neck assessment prior to surgery will help you avoid having to undergo a 2nd surgery with its inherent complications to then remove associated lymph nodes.  70% of thyroid glands are removed unnecessarily, due to unknown risk of cancer (indeterminate cytopathology results). New techniques involving genetic studies performed on thyroid FNA sample helps us avoid unnecessary surgery when negative and what extent of surgery is necessary if positive.

Nodules are fairly common. Thyroid cancer is on the rise and considered one of the fastest growing cancers currently (see news ad KSAT). We believe there are more cancers because technology is finding them sooner and smaller (ultrasensitive ultrasound). There are over 400,000 thyroid cancer patients in the US alive today and very few will die from their disease. The incidents of thyroid cancer in a nodule are less than 10%. If you have a family history of thyroid cancer or you have had radiation to your neck, your rates of cancer may be increased.  The initial assessment should be performed by a skilled thyroid solonologist (a physician who has been trained as a thyroid specialist to perform neck ultrasound). Look for the letters ECNU after your physician’s name to determine if they have extra training specific to this specialty. Endocrine certification in neck ultrasound (ECNU) requires an additional 2 years of specialty training to develop expertise in thyroid, parathyroid, and lymph node assessment.

A thyroidologist (thyroid specialist) is the best skilled person to perform your ultrasound-guided fine needle biopsy. Needle placement in the peripheral 3 mm of the nodule is vital to obtain adequate material for diagnosis. Needles placed in the center of the nodule will inevitably retain necrotic material and possibly false-negative or false positive results.  In addition, a thyroidologist is trained in the proper staining techniques to optimize cytopathology. The proper smear of the biopsy is of utmost importance and takes significant skill (part of the ECNU training). A proper smear is vital to determining whether or not your slides are even amenable to a proper diagnosis. Poorly prepared slides produce doubtful results that require repeated biopsies, and lead to unnecessary surgery. Sadly, more than 1/3 of biopsies performed outside a thyroidologists office are inadequate or indeterminate.

A thyroidologist will only use the best cytopathologist for your FNA diagnosis. Cytopathologists (the physician reading the pathology slides from the tissue obtained from your nodule) should call the slides either benign or malignant. Howeve, even in the best hands, 7%-10% of the time it’s very difficult to make that decision and those biopsies are considered” indeterminate.” Some Cytopathologists call indeterminate rates as high as 44% of the time. This is the primary cause for most unnecessary thyroid surgery.

In the past if your cytopathology was indeterminate, you automatically went to surgery. However since 2011 new genetic tests performed on the FNA sample has significantly decreased the rate of unnecessary surgery by 70%.  See the genetic marker page. Currently, very few doctors are using this technology. Again, look for the ECNU. I use Afirma, Asuragen and Ameripath (see genetic testing page)

If your nodule is cancer, request a pre-surgery ultrasound lymph node mapping. This will not only help in planning your original surgery, but prevent future surgeries by removing all obvious disease at your first surgery. If an abnormal lymph node is found prior to your surgery and ultrasound guided biopsy of the lymph node with thyroglobulin washing should absolutely be performed. Thyroglobulin is your cancer marker. This would dramatically change the surgery to include a lateral neck dissection with your thyroidectomy to remove all abnormal lymph nodes. A pre-surgery ultrasound will alter planned surgery in 20-30% of the time.

Insist that this test be performed before your surgery. In fact, if the surgeon is willing to take you to surgery without having lymph node mapping performed, I would not use that surgeon for any neck surgery.

After finding a clinical thyroidologist, the choice of surgeon is the most important decision to make. Surgery for papillary thyroid cancer is not something to be rushed into. These cancers are extremely slow-growing and there is plenty of time to plan for optimal surgery. This will help prevent a 2nd surgery and complications in the long run. Your thyroidologist knows the good, the bad and the evil. My surgeons wouldn’t think to take a patient to the OR without a proper assessment.

Following surgery, follow-up is based on your prognosis and surgical pathology. Radiation in the form of radioiodine, is no longer recommended for stage I, low risk disease. In fact it is considered harmful since the risk does not outweigh the benefit.  Radioiodine is reserved for treatment in high risk patient’s with stage III and IV disease and in some patients with stage II. However, physicians who routinely give radioactive iodine to low risk patients are not familiar with the current guidelines or standards of care as set forth by the American Thyroid Association (ATA).

“First Do No Harm:” The routine use of radioiodine as well as iodine whole-body scans should be discouraged and are not helpful in most low risk patients. There is no mortality benefit to using I-131 in stage I cancer and most stage II cancers. In addition I-131 can increase the incidence of leukemia, lymphoma, and solid tumors including stomach, kidney, breast, female track, and prostate.

Following surgery, see your thyroidologist 2 weeks postoperatively to determine how much thyroid medication you will need to either replace or suppress thyroid function depending upon your cancer stage. At that time your pathology report should be reviewed thoroughly with you so you can understand the ramifications of treatment and whether or not I-131 would be appropriate for you. A MACIS score of < 6.00 carries a 99% prognosis of a 20 year survival, which means you are unlikely to die from this tumor. This score is based on your age, size of the tumor, complete removal of the tumor, and local invasion outside the thyroid gland into the neck muscles. Thyroid cancer is notorious for returning after many years, so long-term surveillance is necessary.

The appropriate followup depends upon the stage of your tumor and your risk assessment. Even if you have up to 3 lymph nodes that were positive for metastatic disease in your neck, you have excellent long-term outcomes without use of I-131. At your 2w post-op appointment a thyroglobulin level will be performed to determine the extent of thyroid tissue left behind in the thyroid bed. Higher levels may be indicative of metastatic lymph nodes or even chest metastases.

If your cancer is a more aggressive form and a higher stage you may need expert advice obtained at cancer centers that deal with high stage cancer of the thyroid. I work in partnership with M.D. Anderson, but Sloan-Kettering, and Mayo Clinic also have teams of experts in treating advanced cases with spread to the lung, bone and other distant areas. They have access to research therapy protocols which may help buy time or even stall progression.

I hope this has been helpful for you in planning your nodule care.    
Dr. Kathleen Hands