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Acquired Hypothyroidism

Contents
  1. Read book excerpt
  2. Hypothyroidism: Introduction
  3. Hypothyroidism Misdiagnosis
  4. Hypothyroidism Causes
  5. Hypothyroidism Complications
  6. Hypothyroidism Treatments
  7. Latest treatments
  8. News
  9. Clinical trials
  10. Hypothyroidism Overview
  11. More book excerpts for Hypothyroidism

Acquired Hypothyroidism: Excerpt from The 5-Minute Pediatric Consult

Adda Grimberg, MD

Acquired Hypothyroidism - BASICS

Acquired Hypothyroidism - description

Hypothyroidism that occurs after the neonatal period

Acquired Hypothyroidism - epidemiology

Acquired Hypothyroidism - incidence

  • May develop at any age
  • Autoimmune thyroid disorders occur more frequently in children and adolescents with type 1 diabetes mellitus.

Acquired Hypothyroidism - prevalence

Chronic lymphocytic thyroiditis prevalence correlates with iodine intake; countries with the highest dietary iodine also have the highest prevalence.

Acquired Hypothyroidism - risk factors

Acquired Hypothyroidism - genetics

  • Family history of thyroid disease or other autoimmune endocrinopathies increases risk.
  • Genetic predisposition in patients with chronic lymphocytic thyroiditis; 30–40% of patients have a family history of thyroid disease, and up to 50% of their 1st-degree relatives have thyroid antibodies.
  • Weak associations of chronic lymphocytic thyroiditis with certain human leukocyte antigen haplotypes
  • Autoimmune thyroid disease may be part of Schmidt syndrome (type II polyglandular autoimmune disease).
  • Genetic syndromes associated with higher incidence of autoimmune thyroiditis:
    • Down syndrome
    • Turner syndrome (especially those with isochromosome Xq)

Acquired Hypothyroidism - etiology

  • Myriad causes (see “Differential Diagnosis”)
  • Can result from thyroid gland dysfunction (primary hypothyroidism) or from pituitary/hypothalamic dysfunction leading to understimulation of the thyroid gland (secondary and tertiary hypothyroidism)

Acquired Hypothyroidism - associated conditions

  • Vitiligo
  • Other autoimmune endocrinopathies
  • Pernicious anemia

Acquired Hypothyroidism - DIAGNOSIS

Acquired Hypothyroidism - signs & symptoms

  • Early primary hypothyroidism can be asymptomatic.
  • Hypothyroid-related symptoms indicate progression from compensated to uncompensated hypothyroidism.
  • Hypothyroidism may be preceded in some cases by temporary hyperthyroidism (Hashitoxicosis).
  • Goiter may be the presenting sign of acquired hypothyroidism; tenderness suggests an infectious process.

Acquired Hypothyroidism - history

  • Linear growth failure can be the 1st sign of thyroid dysfunction.
  • Declining school performance is a sensitive marker for lethargy and reduced focusing.
  • Radiation exposure, history of diabetes, family history of autoimmune disease

Acquired Hypothyroidism - physical exam

  • Bradycardia: Thyroid hormone has cardiac effects.
  • Short stature (or fall-off on growth curve) and increased upper/lower segment ratio: Euthyroidism is required to maintain normal growth.
  • Goiter: Note consistency, symmetry, nodularity, signs of inflammation:
    • May give a clue regarding cause of hypothyroidism
    • May provide a clinical marker to follow during therapy
  • Myxedema (water retention) is not limited to subcutaneous tissue; it may also lead to cardiac failure, pleural effusions, and coma.
  • Muscle hypertrophy, yet muscle weakness most obvious in arms, legs, and tongue; hypothyroidism causes disordered muscle function.
  • Delayed relaxation phase of deep tendon reflexes due to slowed muscle contraction
  • Pale, cool, dry, carotenemic skin due to decreased cell turnover
  • Increase in lanugo hair in children; can be reversed with treatment
  • Sexual development is an important factor.
  • Hypothyroidism can be associated with:
    • Delayed puberty (due to low thyroid hormone level)
    • Precocious puberty and galactorrhea (due to elevated TSH)

Acquired Hypothyroidism - tests

Acquired Hypothyroidism - lab

  • TFree TAntithyroglobulin and antimicrosomal (antiperoxidase) antibodies are markers for chronic lymphocytic thyroiditis.
  • The following conditions may test false-positive for acquired hypothyroidism:
    • Thyroid-binding globulin deficiency: Low total TPeripheral resistance to thyroid hormone: Normal/High total T“Euthyroid sick” syndrome: low T
    • The following tests may be affected in acquired hypothyroidism:
      • Serum creatinine: Elevated due to reduced glomerular filtration rate
      • LDL cholesterol level: Elevated due to decreased LDL receptor expression
      • Creatine kinase: Increased; hypothyroidism is a rare cause of rhabdomyolysis

    Acquired Hypothyroidism - imaging

    Head MRI for suspected secondary/tertiary hypothyroidism or pituitary or hypothalamic lesion

    Acquired Hypothyroidism - differencial diagnosis

    • Immunologic:
      • Chronic lymphocytic thyroiditis (Hashimoto thyroiditis)
      • Polyglandular autoimmune syndrome (Schmidt syndrome)
    • Infectious:
      • Postviral subacute thyroiditis
      • Associated with congenital infections:
        • Rubella
        • Toxoplasmosis
    • Environmental:
      • Goitrogen ingestion:
        • Iodides
        • Expectorants
        • Thioureas
    • Iatrogenic:
      • Following surgical thyroidectomy for thyroid cancer, hyperthyroidism, or extensive neck tumors
      • Following radioiodine ablative therapy for hyperthyroidism or thyroid cancer
      • Following irradiation to the head or neck for cancer treatment
      • Medications: lithium, amiodarone, iodine contrast dyes, tiratricol (an OTC fat-loss supplement)
    • Metabolic:
      • Cystinosis
      • Histiocytosis X
    • Congenital:
      • Late-onset congenital-large ectopic gland
    • Genetic syndromes:
      • Down syndrome
      • Turner syndrome
      • Secondary or tertiary hypothyroidism
      • Hypothalamic or pituitary disease
    • Consumptive hypothyroidism:
      • Due to increased type 3 iodothyronine deiodinase activity in hemangiomas

    Acquired Hypothyroidism - TREATMENT

    Acquired Hypothyroidism - medication

    L-Thyroxine (synthetic thyroid hormone) replacement

    • Indicated for the treatment of overt or compensated hypothyroidism
    • 2–5 mcg/kg/d PO, once daily
    • Monitor TDuration of therapy:
      • Lifetime
      • In 30% of the cases, children with chronic lymphocytic thyroiditis will undergo spontaneous remission.
      • Need for treatment can be reassessed after growth is completed.

    Acquired Hypothyroidism - FOLLOW UP

    Acquired Hypothyroidism - prognosis

    • If patients are compliant, prognosis is excellent.
    • Treated patients often resume growth at a rate greater than normal (catch-up growth).
    • In children in whom treatment has been delayed, catch-up growth may not fully normalize height to predicted values.
    • Other signs and symptoms resolve at a variable rate.
    • Goiters in chronic lymphocytic thyroiditis may not completely regress with treatment (enlargement due to persistent inflammation does not correct, though TSH-mediated hypertrophy will).

    Acquired Hypothyroidism - complications

    • Most significant complication is impaired linear growth.
    • Puberty can also be affected.
    • Myxedema coma may occur.
    • Encephalopathy of varied clinical presentation has been associated with high titers of thyroid antibodies, especially antimicrosomal; responds well to corticosteroid treatment.

    Acquired Hypothyroidism - patient monitoring

    • Whenever starting medication or adjusting dose, check TMonitor response to treatment by measuring T

      Acquired Hypothyroidism - bibliography

      1. Ai J, Leonhardt JM, Heymann WR. Autoimmune thyroid diseases: Etiology, pathogenesis, and dermatologic manifestations. J Am Acad Dermatol. 2003;48:641–659.
      2. Ban Y, Tomer Y. Genetic susceptibility in thyroid autoimmunity. Pediatr Endocrinol Rev. 2005;3:20–32.
      3. Barbesino G, Chiovato L. The genetics of Hashimoto’s disease. Endocrinol Metab Clin North Am. 2000;29:357–374.
      4. Betterle C, Volpato M, Greggio AN, et al. Type 2 polyglandular autoimmune disease (Schmidt syndrome). J Pediatr Endocrinol Metab. 1996;9(Suppl 1):S113–S123.
      5. Hunter I, Greene SA, MacDonald TM, et al. Prevalence and aetiology of hypothyroidism in the young. Arch Dis Child. 2000;83:207–210.
      6. Nabhan ZM, Kreher NC, Eugster EA. Hashitoxicosis in children: Clinical features and natural history. J Pediatr. 2005;146:533–536.
      7. Pearce EN, Farwell AP, Braverman LE. Thyroiditis. N Engl J Med. 2003;348:2646–2655.
      8. Ranke MB. Catch-up growth: New lessons for the clinician. J Pediatr Endocrinol Metab. 2002;15(Suppl 5):S1257–S1266.
      9. Roldan MB, Alonso M, Barrio R. Thyroid autoimmunity in children and adolescents with Type 1 diabetes mellitus. Diabetes Nutr Metab Clin Exp. 1999;12:27–31.
      10. Schmiegelow M, Feldt-Rasmussen U, Rasmussen AK, et al. A population-based study of thyroid function after radiotherapy and chemotherapy for a childhood brain tumor. J Clin Endocrinol Metab. 2003;88:136–140.
      11. Stathatos N, Wartofsky L. Perioperative management of patients with hypothyroidism. Endocrinol Metab Clin N Am. 2003;32:503–518.
      12. Surks MI, Ortiz E, Daniels GH, et al. Subclinical thyroid disease: Scientific review and guidelines for diagnosis and management. JAMA. 2004;291:228–238.
      13. Watemberg N, Greenstein D, Levine A. Encephalopathy associated with Hashimoto thyroiditis: Pediatric perspective. J Child Neurol. 2006;21:1–5.
      14. Weber G, Vigone MC, Stroppa L, et al. Thyroid function and puberty. J Pediatr Endocrinol Metab. 2003;16(Suppl 2):S253–S257.

      Acquired Hypothyroidism - CODES

      Acquired Hypothyroidism - icd9

      244.9 Acquired hypothyroidism

      Acquired Hypothyroidism - FAQ

      • Q: What happens if my child forgets a dose?
      • A: Give the dose as soon as you remember. If it is the next day, give 2 doses.
      • Q: How long will my child have to take these pills?
      • A: Probably for life.
      • Q: Are there any side effects from the medication?
      • A: No The medication contains only the hormone that your child’s thyroid gland is not making. The hormone is made synthetically, so there is also no infectious risk.
      • Q: If my child takes twice the dose, will his or her growth catch up faster?
      • A: Your child may grow a little faster but will also have adverse effects from having too much thyroid hormone.
      • Q: Does the medication have to be taken at any particular time of day?
      • A: No, but consistently choosing the same time of day helps to remember to take it. Do not take simultaneously with soy products or raloxifene (an antiestrogen medication) because they can cause malabsorptions of levothyroxine.
      • Q: What if my child needs surgery?
      • A: Treatment of hypothyroidism such that the patient is euthyroid (normal thyroid status) prior to surgery is preferable whenever possible (only exception is ischemic heart disease requiring surgery). Euthyroid sick syndrome, which is common in very ill patients, should not be treated.

      Book Source Details

      • Book Title: The 5-Minute Pediatric Consult
      • Author(s): M. William Schwartz MD; et al.
      • Year of Publication: 2008
      • Copyright Details: The 5-Minute Pediatric Consult, Copyright © 2008 Lippincott Williams & Wilkins.

      More About Hypothyroidism

      More Medical Textbooks Online about Hypothyroidism

      Review other book chapters online related to Hypothyroidism:

      Medical Books Excerpts
      • Hypothyroidism
      • "The 10-Minute Diagnosis Manual: Symptoms and Signs in the Time-Limited Encounter" (2000)
      • [ read ]
       

      Copyright notice for book excerpts: Copyright © 2008 Lippincott Williams & Wilkins. All rights reserved.



      More About This Book:
      Title: The 5-Minute Pediatric Consult
      Authors: M. William Schwartz MD; et al.
      Publisher: Lippincott Williams & Wilkins
      Copyright: 2008
      ISBN: 0-7817-7577-9

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