Puberty Goiter

Definition

Pubertal goitre describes thyroid enlargement occurring during puberty when rapid somatic growth and hormonal changes alter thyroid physiology.

Epidemiology and clinical relevance

• Peak incidence in early to mid‑puberty; female predominance (ratio increases after menarche).
• Prevalence varies with iodine status and regional endemicity. In iodine‑sufficient areas most adolescent goitres are autoimmune or colloid; in endemic areas iodine deficiency predominates.
• Clinical importance: potential impact on linear growth, pubertal timing, psychosocial development and, rarely, malignancy risk in nodular disease.

Pathophysiology

• Physiologic mechanisms in puberty:
  • Increased metabolic demand and growth hormone/IGF‑1 surge increase thyroid hormone turnover and thyroidal requirement.
  • Sex steroids (estrogen) upregulate thyroxine‑binding globulin and may modify thyroid antigen presentation, favouring autoimmune expression in genetically predisposed adolescents.
• Pathologic mechanisms:
  • Autoimmune lymphocytic infiltration (Hashimoto) causes diffuse enlargement, then atrophy; germinal centre formation and anti‑TPO/anti‑TG production mediate damage.
  • Iodine deficiency → compensatory TSH‑driven follicular hyperplasia and colloid accumulation.
  • Dyshormonogenesis (enzyme defects) → goitre from TSH stimulation.
  • Nodular transformation/multinodular goitre from repeated hyperplasia/regression cycles. Risk of autonomous function in older adolescents.
  • Infiltrative disease, neoplasia (papillary carcinoma most common in pediatrics), and drug/iatrogenic causes (amiodarone, lithium, radiotherapy) produce enlargement by distinct mechanisms.

Aetiology — concise differential

1. Physiologic pubertal (transient) goitre.
2. Autoimmune thyroid disease — Hashimoto (most common in iodine‑sufficient adolescents); autoimmune hyperthyroidism (Graves) may present with diffuse enlargement.
3. Iodine deficiency or excess (contrast/antiseptics) and environmental goitrogens.
4. Dyshormonogenesis (congenital defects presenting or unmasked in adolescence).
5. Multinodular goitre, solitary nodules (consider malignancy: papillary carcinoma most frequent in children).
6. Subacute (de Quervain) and painless (silent) thyroiditis.
7. Infiltrative disease and neoplasia (primary thyroid lymphoma rare; metastasis uncommon).
8. Iatrogenic/medication induced (radiation, surgical remnant, drugs).
9. Secondary to pituitary TSH‑secreting adenoma (rare).

Clinical evaluation — focused on red flags and functional impact

• History: duration, growth trajectory, school performance, weight changes, heat/cold intolerance, palpitations, tremor, menstrual history, family autoimmune disease, prior radiation/neck surgery, drug exposures, iodinated contrast, and systemic B symptoms.
• Examination: goitre size (WHO/ultrasound volume), symmetry, nodularity, firmness, tenderness, cervical lymphadenopathy, compressive signs (dysphagia/stridor), signs of thyroid dysfunction, growth parameters, pubertal staging, skin and systemic exam for other autoimmune disease.
• Red flags: rapidly enlarging painless mass, unilateral dominant nodule, fixed hard gland, cervical adenopathy, compressive symptoms — urgent FNA and oncologic workup.

Investigations — targeted and staged

1. Baseline tests for all adolescents with goitre:
   • Serum TSH and free T4 (age‑specific ranges).
   • Anti‑TPO and anti‑TG antibodies.
2. If thyrotoxicosis is suspected: TSH‑receptor antibodies, total T3, radioactive iodine uptake (RAIU) or 99mTc scan to differentiate Graves vs destructive thyroiditis vs toxic nodule.
3. For euthyroid or hypothyroid goitre: consider serum thyroglobulin (nonspecific), urinary/serum iodine (public‑health contexts), and screening for coexisting autoimmunity (guided testing).
4. Imaging:
   • High‑resolution ultrasound (first‑line): volume estimation, echotexture, vascularity (Doppler), characterize nodules (size, microcalcifications, extrathyroidal extension), and guide FNA.
   • RAIU/scan selectively when functional status uncertain or to evaluate autonomy.
5. Tissue diagnosis:
   • Ultrasound‑guided FNA cytology for nodules ≥1 cm with suspicious features or any dominant/suspicious lesion. Use paediatric cytopathology thresholds and consider molecular testing for indeterminate cytology.
   • In rapidly enlarging mass perform FNA plus flow cytometry/ clonality studies to exclude lymphoma.
6. Endocrine and systemic workup if central or syndromic features: pituitary MRI, morning cortisol/ACTH, GH/IGF‑1, celiac serology, blood glucose, and other autoimmune screens as indicated.

Management — cause‑directed principles

Overarching principle: tailor therapy to aetiology, symptomatology, functional status, growth/puberty impact and malignancy risk. Avoid unnecessary lifelong treatment for physiologic transient enlargement.

1. Observation and reassurance:
   • Small, asymptomatic physiologic pubertal goitres with euthyroidism — monitor clinically and with ultrasound; counsel on iodine‑sufficient diet and follow growth/puberty.
2. Autoimmune (Hashimoto):
   • If overt hypothyroidism → start levothyroxine (age/weight dosing), target age‑appropriate fT4/TSH and normal growth velocity.
   • If euthyroid or subclinical: treat if TSH >10 mIU/L, progressive TSH rise, growth deceleration, dyslipidaemia, or symptomatic; otherwise monitor every 3–6 months.
3. Iodine deficiency/excess:
   • Correct iodine deficiency via public health measures/supplementation. Avoid excess iodine exposure; treat hypothyroidism if present.
4. Diffuse toxic goitre (Graves):
   • Options: antithyroid drugs (carbimazole/methimazole) titration or block‑and‑replace, radioiodine (post‑pubertal with careful counselling), or surgery (subtotal/near‑total thyroidectomy) in selected cases; consider age, severity, and relapse risk.
5. Nodular disease:
   • FNA‑guided management; benign cytology → surveillance; suspicious/malignant → surgical management with paediatric thyroid cancer protocols (total thyroidectomy, lymph node dissection as indicated, postoperative radioiodine and TSH suppression therapy).
6. Rapid enlargement/lymphoma:
   • Urgent FNA with immunophenotyping; lymphoma management multidisciplinary (chemo ± radiotherapy); avoid unnecessary thyroidectomy.
7. Surgery:
   • Indications: compressive symptoms, suspicious/malignant nodules, large cosmetically concerning goitre, or failure of medical therapy in selected toxic or obstructive cases. Use experienced paediatric endocrine surgeons to minimise complications (hypoparathyroidism, recurrent laryngeal nerve injury).
8. Iatrogenic/medication:
   • Stop offending drugs when feasible; treat dysfunction as per thyroid status.
9. Public health and family counselling:
   • Screen family for autoimmune disease when indicated, ensure iodine sufficiency, and address psychosocial impact.

Special considerations in adolescents

• Growth and pubertal timing: monitor growth velocity and bone age. Treat early hypothyroidism aggressively to preserve height potential.
• Fertility and pregnancy planning in older adolescents: counsel regarding euthyroidism for conception; adjust levothyroxine dose in pregnancy.
• Psychosocial and cosmetic concerns: provide counselling; consider earlier surgical referral for large cosmetically distressing goitres after medical optimization.
• Transition of care: ensure structured handover to adult endocrine services with documentation of aetiology, pathology, treatment course and surveillance plan.

Complications and prognosis

• Prognosis depends on cause: physiologic pubertal goitre usually regresses; autoimmune disease often chronic and may require lifelong levothyroxine; nodular disease carries malignancy risk (higher malignancy rate in paediatric nodules than adults).
• Complications: persistent hypothyroidism, thyrotoxicosis, compressive symptoms, cosmetic impact, and rare progression to lymphoma or carcinoma in nodular disease.