Goiter.

• •Mild enlargement of the lower neck noticed only on close inspection or palpation by a clinician
• •Elevated TSH on routine bloodwork without symptoms — subclinical hypothyroidism from early Hashimoto's
• •Mild dysphagia limited to specific foods (rice, bread) in middle-aged women
• •Family history of goiter, autoimmune thyroid disease, or thyroid cancer in first-degree relatives

Diagnosis begins with a structured neck examination and is anchored by three questions: how large is the goiter, what is the thyroid function, and are there any suspicious nodules? Inspection identifies asymmetry, scars, and visible bulging; palpation from behind the patient with swallowing assesses size, consistency, mobility, and any discrete nodules. Auscultation may detect the bruit of Graves' disease. Initial laboratory testing is TSH (with reflex free T4 and free T3 if abnormal), thyroid peroxidase antibody (TPO Ab), and thyroglobulin antibody (Tg Ab) to identify autoimmune disease. TSH-receptor antibody (TRAb) is added when Graves' disease is suspected. Ultrasound is the single most useful imaging study: it confirms gland enlargement, characterizes any nodules using the ACR TI-RADS or ATA stratification system (composition, echogenicity, shape, margins, echogenic foci), and identifies suspicious cervical lymphadenopathy. Fine-needle aspiration (FNA) under ultrasound guidance is recommended for nodules ≥1 cm with intermediate or high-suspicion features, or ≥1.5-2 cm for lower-risk nodules, per ATA 2015 guidelines. Bethesda system cytology categories guide management. Radioiodine (I-123) or technetium-99m thyroid scan is used selectively when TSH is suppressed to identify a 'hot' autonomous nodule vs the diffuse uptake of Graves'. CT or MRI without contrast is reserved for very large or substernal goiters to plan surgery; iodinated contrast should be avoided when possible due to thyroid uptake. Spirometry or flow-volume loops can quantify tracheal compression. The combination of TSH plus ultrasound resolves the majority of cases on first visit.

• ✓Levothyroxine (1.6 µg/kg/day in healthy adults; titrate to TSH 0.5-2.5 mIU/L)
• ✓Methimazole (10-40 mg daily, divided initially)
• ✓Propylthiouracil (100-300 mg daily)
• ✓Radioactive iodine (I-131 ablation)

Chronic iodine deficiency

The most common cause worldwide. Sustained dietary iodine below 100 µg/day reduces thyroid hormone production; the pituitary responds by increasing TSH, which drives thyroid hyperplasia. Endemic iodine deficiency persists in mountain and inland regions of Africa, South Asia, and Eastern Europe.

Hashimoto's thyroiditis (chronic autoimmune thyroiditis)

The leading cause of goiter in iodine-sufficient countries. Anti-thyroid peroxidase and anti-thyroglobulin antibodies drive lymphocytic infiltration, fibrosis, and slowly progressive thyroid failure. The gland is initially enlarged and firm, becoming smaller and atrophic in late disease.

Graves' disease

Autoimmune diffuse toxic goiter driven by TSH-receptor stimulating antibodies (TRAb), which mimic TSH and cause both diffuse enlargement and overproduction of thyroid hormone. Often accompanied by orbitopathy and pretibial myxedema.

Multinodular goiter (sporadic, non-toxic)

Develops over years from focal hyperplasia and clonal expansion within the thyroid. Each nodule reflects a small genetic or acquired change in a single thyrocyte lineage. Prevalence rises with age, reaching 30-50% by age 60 on ultrasound.

Inherited dyshormonogenesis

Rare autosomal recessive defects in thyroid hormone synthesis (TPO, TG, DUOX2, SLC5A5, SLC26A4 mutations) cause congenital goiter, usually with hypothyroidism. Pendred syndrome combines goiter with sensorineural deafness.

Goitrogenic foods and medications

Cassava, soy, millet, and cabbage-family vegetables can contribute to goiter in iodine-deficient settings. Lithium, amiodarone, perchlorate, and excess iodine itself (Wolff-Chaikoff effect or Jod-Basedow) all alter thyroid function and can drive goiter.

Thyroid neoplasms

Both benign (follicular adenoma) and malignant (papillary, follicular, medullary, anaplastic) thyroid neoplasms present as nodules within a goiter. Rapid growth, hard fixed nodules, vocal cord paralysis, and lymphadenopathy raise concern for malignancy.

Female sexnon-modifiable

Women have 4-5x higher prevalence of goiter and nodular disease in iodine-sufficient regions, driven partly by estrogen effects on thyroid growth and a higher prevalence of autoimmune thyroid disease.

Iodine intake below WHO recommended levelsmodifiable

Dietary iodine below 100 µg/day in adults (150 µg in pregnancy) drives endemic goiter. Universal salt iodization has reduced goiter prevalence in supplemented countries by 50-80% over decades.

Family history of thyroid diseasegenetic

First-degree relatives with goiter, Hashimoto's, Graves', or thyroid cancer raise individual risk 2-4 fold. Specific susceptibility loci include HLA-DR3, CTLA4, PTPN22, and TSHR.

Pregnancy and postpartumnon-modifiable

Iodine demand rises 50% in pregnancy. Pre-existing borderline iodine deficiency can manifest as gestational goiter. Postpartum thyroiditis occurs in 5-10% of women within 12 months of delivery.

External radiation exposure to the neckenvironmental

Childhood radiation for tinea capitis, acne, lymphoma, or accidental nuclear exposure raises goiter and thyroid cancer risk for decades. Risk peaks for exposures under age 15.

Smokingmodifiable

• •Iodine-rich foods — seafood, dairy products, eggs, and iodized salt
• •Selenium-rich foods (Brazil nuts, sardines, eggs) — selenium supports thyroid hormone metabolism and antioxidant defense
• •Adequate iron and zinc, both required for thyroid hormone synthesis
• •Mediterranean-style diet rich in vegetables, whole grains, and oily fish

• •Excessive iodine intake (kelp supplements, povidone-iodine gargles) — can paradoxically cause hypothyroidism or trigger thyrotoxicosis in autonomous nodules
• •Raw cassava, raw cabbage-family vegetables, and uncooked soy in large quantities, especially during iodine-deficient periods
• •Concurrent ingestion of levothyroxine with coffee, calcium, or iron supplements — separate by at least 30-60 minutes
• •Crash dieting during early thyroid hormone replacement — can interfere with dose stabilization