TSH & Thyroid Guide
What TSH levels mean, high vs low TSH, hypothyroidism vs hyperthyroidism, and how thyroid lab tests help diagnose and monitor thyroid conditions.
What Is TSH in a Blood Test?
Understand TSH (thyroid-stimulating hormone) in your blood test: normal range, what high TSH and low TSH levels mean, hypothyroidism and hyp…
What Does High TSH Mean?
What a high TSH blood test result means: causes of elevated TSH including Hashimoto's thyroiditis, when levels are dangerously high, and wha…
What Does the Thyroid Do?
Learn what the thyroid gland does in the body: how it regulates metabolism, heart rate, body temperature, brain development and cholesterol,…
What Is Considered a Dangerously High TSH Level?
TSH above 10 mIU/L is overt hypothyroidism; above 50 is dangerously high. Learn the thresholds and symptoms of severe hypothyroidism.…
What Does Low TSH Mean?
Low TSH (below 0.4) usually means hyperthyroidism. Causes include Graves' disease, toxic nodules, thyroiditis, and over-replacement with thy…
What Is Hypothyroidism?
Hypothyroidism (underactive thyroid) explained: causes including Hashimoto's, symptoms, diagnosis, and treatment with levothyroxine.…
What Is Hyperthyroidism?
Hyperthyroidism (overactive thyroid) explained: causes (Graves' disease, toxic nodules), symptoms (rapid heart rate, weight loss, anxiety), …
What Is Hashimoto's Thyroiditis?
Hashimoto's explained: the autoimmune cause of hypothyroidism, anti-TPO antibodies, symptoms, diagnosis, and treatment.…
Can Hypothyroidism Be Cured?
Hashimoto's is lifelong, but drug-induced and subclinical cases may reverse. Learn which types are permanent and which are temporary.…
How to Treat Hypothyroidism
Hypothyroidism treatment: levothyroxine dosing, TSH monitoring, alternatives (desiccated thyroid, liothyronine (T3)), and lifestyle factors.…
What Causes Hypothyroidism?
Causes: Hashimoto's (most common), thyroid surgery, radiation, medications (lithium, amiodarone), iodine deficiency, and congenital.…
What Are Normal TSH Levels?
Normal TSH: adults 0.4-4.0 mIU/L, pregnancy ranges, and why some clinicians prefer 0.5-2.5 as optimal.…
What Is a Low TSH Level in a Woman?
Low TSH in women: causes specific to women include pregnancy, postpartum thyroiditis, and PCOS. When does low TSH need treatment?…
What Does Your Thyroid Do?
Your thyroid regulates metabolism, heart rate, body temperature, brain development, and cholesterol through T3 and T4 hormones. Learn how it…
What Are Thyroid Stimulating Hormones?
TSH (thyroid-stimulating hormone) explained: how the pituitary regulates the thyroid, normal ranges, and what abnormal TSH levels indicate a…
What Are the Symptoms of Thyroid Problems?
Thyroid symptoms: underactive (fatigue, weight gain, cold intolerance, dry skin, constipation) vs overactive (anxiety, weight loss, rapid he…
What Is the Thyroid Gland?
The thyroid gland explained: a butterfly-shaped organ in the neck producing T3 and T4 hormones that regulate metabolism, heart rate, and bod…
How to Check Your Thyroid at Home
Self-check your thyroid: look for neck swelling, feel for nodules while swallowing, and watch for symptoms. But blood tests (TSH) are the on…
What Is Thyroid Storm?
Thyroid storm is a life-threatening hyperthyroid crisis: fever above 104°F, extreme rapid heart rate, confusion, delirium. Requires ICU trea…
What Is Myxedema Coma?
Myxedema coma is a life-threatening hypothyroid crisis: hypothermia, extreme slow heart rate, confusion, unconsciousness. Requires emergency…
What Is a Thyroid Nodule?
Thyroid nodules are lumps in the thyroid gland. 50% of people have them by age 60. 90–95% are benign. Evaluation includes ultrasound and pos…
What Is a Goiter?
A goiter is an enlarged thyroid gland. Causes include iodine deficiency, Hashimoto's, Graves' disease, and nodules. Treatment depends on the…
What Is Graves' Disease?
Graves' disease is an autoimmune condition causing hyperthyroidism. TSI antibodies stimulate the thyroid. Symptoms include bulging eyes, rap…
What Is Thyroid Eye Disease?
Thyroid eye disease (Graves' ophthalmopathy): bulging eyes, double vision, eye irritation. Caused by autoimmune inflammation of eye muscles.…
What Is Postpartum Thyroiditis?
Postpartum thyroiditis affects 5-10% of women after childbirth. Starts with hyperthyroid phase (1-4 months), then hypothyroid phase (4-8 mon…
What Is a Thyroid Uptake Scan?
A thyroid uptake scan uses radioactive iodine to image the thyroid. High uptake = Graves' disease. No uptake = thyroiditis. Focal uptake = t…
What Is a Thyroid Antibody Test?
Thyroid antibody tests (anti-TPO, TSI, anti-thyroglobulin) diagnose autoimmune thyroid disease: Hashimoto's (anti-TPO) and Graves' (TSI).…
How to Read a Thyroid Blood Test
Reading thyroid results: TSH (pituitary signal), free T4 (thyroid output), free T3 (active hormone). High TSH + low T4 = hypothyroidism. Low…
What Is a Thyroid Ultrasound?
Thyroid ultrasound evaluates nodules, goiter, and structure. Cannot measure hormone function — blood tests (TSH) are needed for that.…
What Is Levothyroxine and How Does It Work?
Levothyroxine is synthetic T4 — the standard treatment for hypothyroidism. Take on empty stomach. TSH checked 6-8 weeks after dose changes.…
What Is Radioactive Iodine (RAI) Treatment?
RAI destroys overactive thyroid tissue. Used for hyperthyroidism and thyroid cancer. Usually results in lifelong hypothyroidism requiring re…
What Is Thyroid Hormone Replacement Therapy?
Thyroid replacement provides T4 (levothyroxine) or T4+T3 when the thyroid cannot produce enough. Goal: normalize TSH.…
What Is Subclinical Hypothyroidism?
Subclinical hypothyroidism: elevated TSH (4-10) with normal free T4. 30% progress to overt hypothyroidism. Monitor every 6-12 months.…
What Is Thyroid Peroxidase (TPO) Antibody?
Anti-TPO antibodies attack the thyroid enzyme needed for hormone production. Present in 90-95% of Hashimoto's. Also in 10-15% of healthy peo…
What Is Thyroid Disease?
Includes hypothyroidism, hyperthyroidism, nodules, goiter, cancer. 20 million Americans affected; 60% undiagnosed.…
How Is Hypothyroidism Diagnosed?
TSH above 4.0 with low free T4. Anti-TPO confirms Hashimoto's. Repeat 3+ months apart.…
What Is Thyroid Medication?
Levothyroxine (T4) is standard. Desiccated thyroid and liothyronine (T3) are alternatives. Take on empty stomach.…
What Is Thyroid Cancer?
5-10% of nodules. Papillary (80% of cases) has 98% survival. Detected by ultrasound + FNA. Treatment: surgery + RAI.…
What Are T3 and T4 Thyroid Hormones?
T4 is the prohormone (80%). T3 is the active hormone (3-5x more potent). T4 converts to T3 in tissues.…
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