Thyroid Conditions

Thyroid Conditions:
What You Should Know

Your thyroid is smaller than a golf ball, yet this butterfly-shaped gland at the front of your neck sets the pace for nearly every system you have — metabolism, energy, body temperature, heart rate, and mental clarity. Thyroid conditions develop when the gland produces too much hormone, too little, or changes in size and structure. Because thyroid hormone reaches almost every organ, even a small imbalance can be felt long before it is ever named.

That is why they are so often missed. Fatigue gets blamed on a busy schedule, weight change on age, anxiety on stress — while hypothyroidism, hyperthyroidism, Hashimoto’s thyroiditis, or a thyroid nodule quietly progresses. Women are diagnosed several times more often than men, and risk climbs with family history, autoimmune disease, and the year following pregnancy. At EndoInnova in Hatillo, Dr. Sheila S. Mercado Méndez, a board-certified endocrinologist in Diabetes and Metabolism, evaluates thyroid conditions so the cause is identified rather than assumed.

Common Symptoms
To Watch For

Thyroid symptoms rarely announce themselves. They arrive as a slow drift — a little more tired, a little colder, a few pounds that will not move. An overactive and an underactive thyroid also produce opposite signs, so the pattern usually only becomes clear once blood work is done.

How Are Thyroid
Conditions Diagnosed?

Thyroid conditions are diagnosed with a blood panel measuring TSH and thyroid hormone levels, alongside a physical exam of the neck and a review of your symptoms and medical history. When a nodule or enlargement is found, an ultrasound is added to evaluate the gland’s structure.

TSH alone is where most thyroid testing starts, and where a lot of it wrongly stops. A result inside the reference range can still sit far from where your body functions well, and antibodies can be elevated for years before hormone levels shift at all. Dr. Sheila S. Mercado Méndez reads the full panel as a pattern — values, symptoms, medications, and family history together — rather than judging any single number in isolation.

Test	Normal / Typical Range	Abnormal Result	What It Shows
TSH	0.4–4.0 mIU/L	Elevated: underactive thyroid Suppressed: overactive thyroid	Primary thyroid function
Free T4	Normal range	Low or elevated	Thyroid hormone level
Free T3	Normal range	Low or elevated	Active thyroid hormone
Thyroid Ultrasound	Normal gland	Nodules or enlargement	Thyroid structure

Managing Thyroid Conditions:
Core Treatment Approach

There is no single thyroid treatment, because an underactive gland, an overactive gland, and a structural nodule each call for a different response — and treating one as though it were another can make things worse. The approach is chosen only after testing confirms which condition is present, then adjusted over time as follow-up labs show how your body is responding to the current dose.

Thyroid Hormone Replacement

Daily medication that supplies the hormone an underactive thyroid no longer makes in sufficient amounts. Absorption is affected by timing, food, and other supplements.

Antithyroid Therapy

Medication that slows excess hormone production when the thyroid is overactive, as in Graves' disease, with lab checks during the early adjustment period.

Scheduled Lab Monitoring

Repeat TSH and hormone testing after each dose change, then at set intervals — the only reliable way to catch drift before symptoms return.

Nutrition and Interaction Guidance

Practical direction on iodine sources, biotin supplements, and medications like iron or calcium that can alter your levels or distort your test results.

Procedures and Surgical Referral

When a nodule requires biopsy, or the condition calls for radioactive iodine or thyroidectomy, care is coordinated with the appropriate specialist.

Advanced Technology
in Thyroid Care

Thyroid evaluation has become far more precise than a single blood draw. Better imaging and more sensitive lab assays mean a nodule can be measured and tracked rather than guessed at, and an autoimmune process can be identified years before it changes how you feel. The point is not more testing — it is knowing which test answers the question in front of you.

High-Resolution Thyroid Ultrasound

Sound-wave imaging that measures the gland and characterizes nodules by size, borders, and internal texture — with no radiation and no contrast.

Fine-Needle Aspiration (FNA)

A thin-needle sampling of a nodule, used when ultrasound features suggest it warrants review. Most thyroid nodules are benign; FNA is how that is confirmed rather than assumed.

Comprehensive Thyroid Panels

Testing beyond TSH — free T4, free T3, and thyroid antibodies — to separate autoimmune causes from medication effects and temporary thyroiditis.

Longitudinal Result Tracking

Comparing each panel against your own prior values, so a gradual shift within the reference range is caught as a trend rather than dismissed as normal.

Protecting Your Future Health
with Thyroid Care

Thyroid hormone reaches the heart, the bones, cholesterol metabolism, fertility, and mood — which is why an imbalance left alone rarely stays a neck problem. Untreated hyperthyroidism can drive atrial fibrillation and bone loss. Untreated hypothyroidism can raise LDL cholesterol and slow cognition. Consistent treatment and follow-up are what keep those downstream risks contained.

Most thyroid conditions are managed long-term rather than cured, and they tend to move quietly — levels drift, doses stop fitting, and symptoms return before anyone thinks to retest. Follow-up matters most if you have a family history of thyroid disease, another autoimmune diagnosis, prior neck radiation, or delivered a baby in the past year. Patients from Hatillo, Manatí, Arecibo, Camuy, Quebradillas, and Barceloneta come to EndoInnova for exactly this kind of ongoing thyroid follow-up.

Preventing Thyroid Complications

Frequently Asked
Questions

Common questions about thyroid symptoms, testing, and treatment at EndoInnova. For anything specific to your own lab results, Dr. Mercado Méndez will review them with you during your visit.

What symptoms mean I should get my thyroid checked?

Get your thyroid checked if you have ongoing fatigue, unexplained weight change, cold or heat intolerance, hair thinning, neck swelling, or a racing heartbeat lasting more than a few weeks. A TSH blood test is the usual first step and can be ordered during a standard endocrinology visit.

How is a thyroid condition diagnosed?

Diagnosis begins with a blood panel measuring TSH and free T4, often with free T3 and thyroid antibodies. Dr. Sheila S. Mercado Méndez reviews these alongside your symptoms, medications, and a neck exam. If a nodule or enlargement is present, an ultrasound is added to assess gland structure.

My TSH is normal but I still feel exhausted — what now?

A normal TSH does not rule out a thyroid problem. Antibodies can be elevated for years before TSH shifts, and free T4 or T3 may sit at the edge of range. A fuller panel and clinical review can identify what a single TSH value missed.

Do you treat both hypothyroidism and hyperthyroidism?

Yes. EndoInnova provides endocrinology-led care for underactive thyroid, overactive thyroid, Hashimoto’s thyroiditis, Graves’ disease, goiter, and thyroid nodules. Treatment differs substantially between them, so testing is completed first to confirm which condition is present before any medication plan is discussed.

Will I need thyroid medication for the rest of my life?

It depends on the condition. Hypothyroidism from Hashimoto’s usually requires long-term hormone replacement, while thyroid changes following pregnancy or certain medications may resolve. Dosing is reviewed with repeat lab work, and any adjustment is a clinical decision made with your endocrinologist rather than a fixed timeline.

Are thyroid nodules dangerous?

Most thyroid nodules are benign and never cause problems. Ultrasound assesses size, borders, and internal texture to determine whether a nodule needs sampling or simply periodic monitoring. Fine-needle aspiration is used when imaging features warrant it, so the answer is confirmed rather than assumed.

Can a thyroid problem cause weight gain?

An underactive thyroid can slow metabolism and contribute to modest weight gain, often with fluid retention. It is rarely the sole explanation for significant weight change. Thyroid testing helps determine what role, if any, it plays before weight management is addressed as a separate concern.

Should I get my thyroid tested after having a baby?

Postpartum thyroiditis can develop in the year following delivery and is frequently mistaken for normal exhaustion. If you have persistent fatigue, palpitations, mood changes, or hair loss after giving birth, thyroid testing is reasonable — particularly with a family history of thyroid or autoimmune disease.

Can supplements or other medications affect my thyroid test results?

Yes. Biotin, common in hair and nail supplements, can distort thyroid lab results and produce misleading values. Iron, calcium, and antacids can reduce absorption of thyroid medication. Bring a complete list of supplements and prescriptions to your appointment so results are interpreted accurately.

Where can I see a thyroid specialist in Puerto Rico?

EndoInnova is located in Hatillo and sees patients from Manatí, Arecibo, Camuy, Quebradillas, Barceloneta, and across Puerto Rico. Dr. Sheila S. Mercado Méndez is a board-certified endocrinologist in Diabetes and Metabolism. Appointments can be booked online or by calling +1 787-956-0909.

Answers About Your Thyroid, From a Specialist

If you’ve been told your labs are “normal” but you still feel exhausted, or you’re managing a thyroid condition and something has shifted, the next step is a specialist evaluation rather than more searching. Dr. Sheila S. Mercado Méndez is a board-certified endocrinologist in Diabetes and Metabolism, seeing patients at EndoInnova in Hatillo and from across Puerto Rico’s north coast. Book online or call +1 787-956-0909.

Thyroid Conditions