• Laboratory Evaluation:
  • Diagnosis is always established by the measurement of:
    • Sensitive TSH and thyroid hormone levels (free T3 and free T4)
  • Thyrotoxicosis caused by TNG or Graves’ disease is usually characterized by:
    • A suppressed TSH level with either:
      • Normal (subclinical) or elevated (overt) free thyroid hormone levels
    • It is insufficient to rely on the measurement of TSH or free thyroid hormones:
      • Alone to diagnose TNG or Graves’ disease:
        • Because suppression of TSH or elevation of thyroid hormones can be associated with clinical conditions other than TNG and Graves’ disease

Low TSH	High TSH
Secondary hypothyroidism	TSH-secreting pituitary tumor
Non-thyroidal illness	Thyroid hormone resistance
Glucocorticoid therapy
Amiodarone use
Excessive thyroid hormone therapy

• Other serologic findings:
  • Such as antithyroid antibodies – antithyroid peroxidase and antithyroglobulin:
    • That support the diagnosis of autoimmune thyroid disease:
      • May be detected in patients with Graves’ disease:
        • However, serum TSHR-Ab:
          • Is occasionally helpful in the diagnosis of Graves’ disease:
            • Though there is no consensus regarding its routine measurement in Graves’ disease
• Imaging:
  • Radionuclide Imaging:
    • Radionuclide scanning and radioactive iodine uptake (RAIU):
      • Are useful tests to elucidate the cause of hyperthyroidism
    • In toxic nodular goiter (TNG):
      • The radioactive iodine (RAI) concentration is in the nodule(s), and uptake is inhibited in the surrounding tissue:
        • Giving the appearance of “patchy uptake”
      • Consequently, the total RAIU may be either:
      • Slightly raised or at the upper limit of normal
    • In Graves’ disease:
      • Because of the diffuse thyroid involvement:
        • The RAIU is always intense and increased
    • Thyroid radionuclide imaging may not be necessary in every case:
      • When the diagnosis is obvious:
        • But it is helpful in the differentiation of other clinical conditions associated with hyperthyroidism but with low RAIU

Clinical Conditions Associated with Low Radioactive Iodine Uptake and Hyperthyroidism

Thyroiditis

Iodine-induced thyrotoxicosis

Exogenous thyrotoxicosis (factitia)

Ectopic functional thyroid tissue

• Computed tomography scan:
  • In any patient with compressive or obstructive symptoms and an MNG:
    • Chest radiography and chest computed tomography (CT) are often informative
  • Chest CT is particularly valuable to define the size and extent of the goiter:
    • Especially into the mediastinum
  • Care to avoid iodinated contrast:
    • Until the patient’s thyroid functional status must be taken into account or the significant iodine load CT contrast agent may acutely induce or worsen hyperthyroidism

• Associated metabolic abnormalities:
  • Altered glucose metabolism:
    • Reversible hyperglycemia
    • Elevated C-peptide
    • Elevated intact proinsulin
    • Insulin resistance
  • Increased bone turnover:
    • Elevated markers of bone formation and resorption
      • Are hallmarks of untreated hyperthyroidism
  • Untreated hyperthyroidism is associated with an elevated chromogranin A level:
    • That changes in parallel with thyroid status

Metabolic Abnormalities Associated with Hyperthyroidism

Mild hypercalcemia

Myopathy

Hypokalemic periodic paralysis

Pulmonary hypertension

Cholestatic jaundice

#Arrangoiz #CancerSurgeon #ThyroidSurgeon #ParathyroidSurgeon #HeadandNeckSurgeon #ThyroidExpert #SurgicalOncologist #EndocrineSurgery #CASO #Miami #ThyroidNodule #ToxicNodularGoiter #TNG #MultinodularGoiter #GravesDisease #Hyperthyroidism #Goiter #CenterforAdvancedSurgicalOncology