Thyroid Center of New Hampshire

About Us

The Thyroid Center of New Hampshire, located at St. Joseph Hospital in Nashua, NH, is a comprehensive, full-service endocrine clinic providing expert thyroid care to both new and existing patients. Our two board-certified providers, Mikhail Signalov, DO, and Shellie Hafer, APRN, understand that conditions relating to the thyroid often affect many other systems throughout the body. That’s why we proudly offer our patients the guidance, treatment, and both short and long term condition management they need along with the convenience of high-quality care all in one place.

Your First Appointment: What to Expect

Your first visit with one of our thyroid specialists is not much different than a regular doctor. It includes an analysis of your medical history, a full body examination, and possibly blood and urine samples. We also recommend patients bring a notebook of their most recent symptoms as well as a list of any medications that they are currently taking.

About the Thyroid

The thyroid is a small, butterfly shaped gland situated at the bottom of your neck, just below the Adam’s apple. Hormones produced by the thyroid gland – triidothyronine (T3) and thyroxine (T4) – have an enormous impact on your health. Thyroid hormones affect every cell and all organs of the body. Some of their primary functions include:

  • Regulation of the rate at which calories are burned, affecting weight loss or weight gain
  • Can slow down or speed up the heartbeat
  • Can raise or lower body temperature
  • Influence the rate at which food moves through the digestive tract
  • Control the way muscles contract
  • Control the rate at which dying cells are replaced

What is a Thyroid Specialist?

A thyroid specialist is an endocrinologist with a special focus on diagnosing, treating, and managing conditions relating to the thyroid. Many primary care providers will run a general thyroid test through blood work every year and based on those results, they may recommend you visit a thyroid specialist who will perform further testing to determine what the condition may be.

Common Thyroid Conditions

Hypothyroidism (underactive thyroid) is a condition in which the thyroid gland does not produce enough of crucial hormones. This is something both Mikhail Signalov, DO, and Shellie Hafer, APRN, see very frequently. Symptoms of this condition can be easy to miss in the early stages by a primary care provider, which is why it is so important to visit a thyroid specialist. Over time, untreated hypothyroidism can cause a large number of health problems, including obesity, joint pain, infertility, and heart disease. The signs and symptoms of hypothyroidism can vary from patient to patient, as well on the severity of the condition. Some of these symptoms may include:

  • Fatigue
  • Increased sensitivity to cold
  • Constipation
  • Weight gain
  • Puffy face
  • Thinning hair
  • Muscle aches, tenderness, and stiffness
  • Dry skin

Hyperthyroidism (overactive thyroid) is a condition in which the thyroid gland produces too much of certain hormones. Like hypothyroidism, this is something that both Mikhail Signalov, DO, and Shellie Hafer, APRN, see very frequently. Most patients respond well once hyperthyroidism is diagnosed and treated. Over time, hyperthyroidism left without treatment can lead to several health concerns, including acceleration of the body’s metabolism, unintentional weight loss, and rapid or irregular heartbeat. The signs and symptoms can vary from patient to patient, as well as on the severity of the condition. Some of those symptoms may include:

  • An enlarged thyroid gland (goiter), which may appear as swelling at the base of the neck
  • Tremor – usually in the hands or fingers
  • Sweating
  • Nervousness, anxiety, or irritability
  • Change in menstrual patterns
  • Rapid heartbeat/irregular heartbeat
  • Fine, brittle hair
  • Increased sensitivity to heat

There are several different types of thyroid cancers. Some grow very slowly over long periods of time, while others can become extremely aggressive over a much shorter period. The Thyroid Center of New Hampshire has an ultrasound machine and technologist during regular office hours, to be able to monitor patients progress – without them having to even leave the office.

We work closely with St. Joseph Hospital’s Cancer Center, as well as with St. Joseph Hospital’s Surgical Services, to properly treat thyroid cancer. Fortunately, most patients diagnosed with thyroid cancer respond very well to treatment, with a survival rate exceeding 97%. Good outcomes require proper treatment and monitoring – which is when our two specialists – Mikhail Signalov, DO, and Shellie Hafer, APRN, come into the picture.

The Thyroid Center of New Hampshire provides comprehensive, compassionate care for thyroid cancer. Working closely with skilled surgeons, pathologists, and radiation oncologists, the center strives for early detection, quality treatment, and long-term surveillance for recurrence.

Ultrasound Guided Fine Needle Aspiration

According to the American Cancer Society, 43,800 new cases of thyroid malignancy will be detected in 2022 and over 2000 deaths will be associated with this type of cancer. Until recently, thyroid malignancy was the most frequently diagnosed cancer in the United States. Malignant thyroid nodules are present in approximately 6% of the population and can be primarily detected through Ultrasound Guided Fine Needle Aspiration (FNA). This exclusive procedure uses sound waves to help locate a nodule or abnormality within the thyroid to remove a tissue sample for further examination under a microscope. Continue reading below on how the specialists at the Thyroid Center of New Hampshire perform this procedure.

As a part of our ongoing efforts to best serve the Greater Nashua Community, St. Joseph Hospital proudly offers Ultrasound Guided Fine Needle Aspiration. Mikhail Signalov, DO, is one of the only providers in New Hampshire that is able to perform this procedure, and holds an Endocrine Certification in Neck Ultrasound (ECNU). This certification requires extensive knowledge and training in ultrasonography to be able to perform consultations and diagnostic evaluations for thyroid and parathyroid disorders.

Mikhail Signalov, DO, performs Ultrasound Guided Fine Needle Aspiration in-office under ultrasound guidance. In the majority of cases, local anesthesia is not necessary and patient discomfort is minimal. The procedure is performed with very thin (27 Gage) needles, which are used for obtaining a thyroid cells for further analysis. In order to receive accurate results, he will normally use at least four needles to evaluate one nodule. As the needles are visualized on the ultrasound throughout the entire procedure, complications are extremely rare. A study conducted at Mayo Clinic based on 585 procedures indicated that in 90% of patients level of discomfort was only 2 (on a scale of 1-10) regardless of using or not using local anesthetics.

  • Avoid Aspirin or Ibuprofen like medications (Advil, Aleve, Motrin, etc.) for at least 5 days prior to procedure
  • Avoid any makeup/lotions
  • V-neck shirt is preferred for procedure
  • Avoid any blood thinners for at least 24 hours after the procedure (please notify office in advance if you are currently on any blood thinners)

The risk of having an Ultrasound Guided Fine Needle Aspiration are minimal can include local soreness, bruising, bleeding, and infection. One of the most common issues is non-diagnostic results, which can happen if not enough cells are collected during the initial sampling. However, this issue is extremely rare and is accounted for less than 5% of biopsies. Our specialists recommend that you can return to normal daily immediately after the procedure. If you develop any complications such as worsening pain, swelling, increased redness of the biopsy site, signs of skin infection or irritation, please contact our office immediately.

After the Ultrasound Guided Fine Needle Aspiration is performed, the specimens obtained are sent to Outpatient Pathology Associates (OPA) in California, our leading experts in thyroid cytopathology. Cytology results are usually reported within 7-10 business days. In most cases, the pathologist is able to provide a define diagnosis of the nodule, in which Mikhail Signalov, DO, will review and configure a proper treatment plan. However, in about 25% of cases, results come back as indeterminate (ambiguous). The risk of malignancy associated with indeterminate cytology can be up to 30%.

In the past, patients who were diagnosed with indeterminate nodules required a repeat Ultrasound Guided Fine Needle Aspiration or surgical resection of at least half of the thyroid gland. With St. Joseph Hospital’s advanced technology, genetic analysis can be performed to avoid unnecessary surgery the risks that come along with it. In cases where no mutations were found, molecular genetics suggest minimal (usually 3%) risk of cancer and instead of surgery, allows for patients to continue conservative follow ups with providers.

Additional Common Conditions and Procedures

Large symptomatic thyroid and parathyroid cysts can be treated by draining and injection of purified alcohol, also known as Percutaneous Ethanol Injection. Mikhail Signalov, DO, has extensive training and experience with this simple, yet effective procedure. This procedure can also be used in selected cases of thyroid cancer.

Some conditions relating to the thyroid may not be able to be controlled through medications. Surgery may be required for efficient treatment. A thyroid lobectomy and hemilobectomy are surgeries that remove part of the thyroid gland, whereas a total thyroidectomy removes the entire thyroid gland. Thyroid cancer treatment usually requires a total thyroidectomy and, in some cases, removal of lymph nodes in the neck.

Noncancerous nodules sometimes become large enough to cause pain, swallowing, and breathing problems. When this occurs, our specialists will explain their recommendations of surgical procedures. A patient who has part of their thyroid gland removed may not need to take hormone replacement after surgery. However, a patient who has the entire gland removed, will need to take hormone replacement for the rest of their life.


Diabetes is a disease in which your blood glucose, or blood sugar, levels are too high. Glucose comes from the foods you eat. Insulin is a hormone that helps the glucose get into your cells to give them energy.

Meet Our Team

Our team of board-certified providers look forward to caring for you.

Mikhail Signalov, DO

St. Joseph Hospital Endocrinology

Shellie Hafer, APRN

St. Joseph Hospital Endocrinology

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