hyperthyroidism
HYPERTHYROIDISM
Hyperthyroidism is the overactivity of the thyroid gland resulting in excessive production of thyroid hormones.
Symptoms are of gradual onset.
Earliest signs may be emotional lability and motor hyperactivity; decline in school performance may also be noted.
Causes are autoimmune (Grave's disease), inappropriate stimulation by trophic factors, passive release of preformed thyroid hormone stores in response to infections, trauma, or other offensive factors inside the body, and extra-thyroidal sources.

Diagnosis

Thyroid storm or thyroid crisis

  • An acute life-threatening exacerbation of hyperthyroidism
  • Signs & symptoms include high fever, changes in sensorium, restlessness, severe tachycardia & arrhythmia
  • May be precipitated by trauma, infection, dehydration

History

  • A comprehensive history should be elicited
  • Combination of ophthalmopathy & hyperthyroidism is suggestive of Graves’ disease
  • Most patients have (positive) family history of autoimmune thyroid disease

Physical Examination

  • Weight & blood pressure (BP)
  • Heart rate (HR), cardiac rhythm, & respiratory rate (RR)
  • Inspect & auscultate the neck (check size, nodule, texture of goiter; thyroid bruit)
  • Ocular & lymphatic examination
  • Dermatological examination

Laboratory Tests

Serum thyroid-stimulating hormone (TSH) Levels

  • Recommended as initial diagnostic exam for patients suspected to have hyperthyroidism
  • Serum TSH measurement is highly sensitive & specific for the evaluation of hyperthyroidism
  • TSH levels are decreased in patients w/ hyperthyroidism
  • TSH receptor stimulating autoantibodies titers are elevated in Graves’ disease w/ 95% sensitivity & 96% specificity
    • Not routinely measured

Thyroxine (T4) Levels

  • Measure both total & free serum T4 levels
  • Free T4 improves diagnostic sensitivity/specificity when combined w/ measured TSH levels

Triiodothyronine (T3) Levels

  • Measure both total & free T3 levels; total T3 measurement preferred for diagnostic purposes
  • T3 levels may be more elevated than T4

Others

  • T4 binding globulin (TBG), transthyretin (TTR)

Imaging

Ultrasound

  • Useful in evaluating the size & shape of the thyroid, especially in large glands

Radioactive Iodine Uptake (RAIU) Test

  • Recommended to determine the cause of hyperthyroidism
  • Usually normal or elevated in the following: Graves disease, toxic adenoma, toxic multinodular goiter, trophoblastic disease, TSH-producing pituitary adenoma, T3 receptor mutation
  • Near-absent uptake w/ RAIU usually seen in the following: silent thyroiditis, Amiodarone-induced thyroiditis, de Quervain’s thyroiditis, iatrogenic thyrotoxicosis, struma ovarii

Thyroid Scan

  • Recommended for patients w/ presence of thyroid nodularity
Digital Edition
Asia's trusted medical magazine for healthcare professionals. Get your MIMS JPOG - Malaysia digital copy today!
DOWNLOAD
Editor's Recommendations
Most Read Articles
Audrey Abella, 31 Jan 2017
Nonsteroidal anti-inflammatory drug (NSAID) treatment for patent ductus arteriosus (PDA) in preterm infants did not reduce the odds of mortality or bronchopulmonary dysplasia (BPD), a recent US study found.
Jairia Dela Cruz, 13 Oct 2016
Children born to obese mothers are at increased risk of developing autism spectrum disorder (ASD) compared with children born to normal-weight mothers, according to data from a review and meta-analysis.
Yap Te-Lu, Anette Sundfor Jacobsen, 01 Oct 2013

Antenatal hydronephrosis (ANH) is a general term used to describe the dilatation of the fetal renal pelvis and/or its calyces. In pelviectasis, there is only dilatation of the renal pelvis; while in caliectasis, there is dilatation of the calyces. ANH is the most commonly diagnosed congenital urinary tract anomaly, which is detected by prenatal screening in 1–5% of all pregnancies

Yap Te-Lu, Anette Sundfor Jacobsen, 01 Dec 2012

Antenatal hydronephrosis (ANH) is a general term used to describe the dilatation of the fetal renal pelvis and/or its calyces. In pelviectasis, there is only dilatation of the renal pelvis; while in caliectasis, there is dilatation of the calyces. ANH is the most commonly diagnosed congenital urinary tract anomaly, which is detected by prenatal screening in 1–5% of all pregnancies.