Thyroid (hypo/hyperthyroidism)

Thyroid: Order a “Thyroid Cascade.” (should start with measuring TSH and will test more if abnormal TSH)

  1. Hypothyroid (Sx: Fatigue, Increased sensitivity to cold, Constipation, Dry skin, Unexplained weight gain, Puffy face, Hoarseness, Muscle weakness, Elevated blood cholesterol level, Muscle aches, tenderness, and stiffness, Pain, stiffness or swelling in your joints, Heavier than normal or irregular menstrual periods, Thinning hair, Slowed heart rate, Depression, Impaired memory)
    • Tx: Synthyroid (Levothyroxine). Begin treatment if TSH is > +10.
    • Subclinical hypothyroidism: NO Sx, mild increase in TSH (5-10), and normal free T4
      1. NO treatment required!
      2. Only start Tx if TSH +10, Sx are present, ovulatory or menstrual dysfunction, or if antithyroid antibodies are present (measure antithyroid peroxidase: TPO).
  2. Hyperthyroid:
    • Tx plan: 1) US of thyroid, 2) Start medication (Methimazole) low dose and have pt return in 4-6 weeks and retest TSH – adjust dose over time until euthyroid, and 3) refer to Endocrine.
    • Order a thyroid uptake (I-123) scan – most insurance require a Thyroid panel/cascade proving that the T3 and T4 are abnormal along with an abnormal TSH prior to approving
    • Order a diagnostic radioactive I-123 Thyroid scan with uptake to determine whether a thyroid nodule is hot or if the entire thyroid is hot.
    • Order: TSH, T4 free, T3 free, TPO (thyroid peroxidase) antibody, TSI (thyroid stimulating immunoglobin), Thyroglobulin antibody.

[Ex: Ordered an US of the thyroid. Referral was made for Endocrinology. Prescribed Methimazole 5mg PO tid. The patient will return in 4-6 weeks, and at that time, her TSH needs to be rechecked to determine whether she is euthyroid on this present dose of Methimazole or if it needs to be titrated up.]

  1. Methimazole: [Note: Side effect – Agranulocytosis: Check CBC for evidence of marrow suppression if fever, sore throat, or other signs of infection.] Start until euthyroid and then maintain dose.
    1. ***Check HCG (pregnancy) test prior to starting!
  2. Mild: 5mg PO tid (may need to adjust following next TSH measurement; if elevated TSH while on Methomazole, then change to 5mg PO bid.)
  • Moderate: 10mg PO tid
  1. Severe: 20mg PO tid
  1. Propylthiouracil: 100-150mg PO tid
    1. Can cause severe, acute liver failure. Only use if patient cannot tolerate Methimazole or if not a candidate for radioactive iodine therapy or surgery.
    2. Preferred over Methimazole in the 1st trimester of pregnancy.
      1. Pregnancy: PTU be given during the first trimester only. This is because there have been rare cases of liver damage in people taking PTU. After the first trimester, women should switch to methimazole for the rest of the pregnancy.
    3. Myxedema coma: Give ***IV Levothyroxine*** PLUS IV steroids.

Manage thyroid storm in the setting of Graves disease: Steroids, beta-blockers, PTU, and iodine

Treat thyrotoxicosis secondary to thyroiditis:

  • Thyrotoxicosis secondary to Graves disease: beta-blocker, thionamide (PTU or Methimazole), and radioactive iodine ablation versus subtotal thyroidectomy.
  • Thyrotoxicosis secondary to subacute thyroiditis (caused by post-viral inflammation of the thyroid): steroids and NSAIDs.

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