Substernal Goiter Surgery Medication

Updated: Jul 28, 2015
  • Author: William R Ryan, MD; Chief Editor: Arlen D Meyers, MD, MBA  more...
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Medication

Medication Summary

The goals of pharmacotherapy are to reduce morbidity and to prevent complications.

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Thyroid Products

Class Summary

Thyroid hormone replacement is administered to correct hypothyroidism. The starting dose depends on the patient’s weight, age, and other medical problems.

Levothyroxine (Synthroid, Levoxyl, Levothroid, Tirosint, Unithroid)

In its active form, levothyroxine influences the growth and maturation of tissues. It is involved in normal growth, metabolism, and development. Endocrinologists can monitor and adjust the doses to optimal effect. A serum free thyroxine value in the upper third of the reference range is the goal.

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Calcium Salts

Class Summary

Calcium supplementation restores serum calcium levels. These medications are continued until parathyroid function improves. If parathyroid function does not improve with time, the patient may need lifelong calcium medication.

Calcium carbonate (Oystercal, Caltrate, Oysco 500, Tums E-X, Children's Pepto)

Calcium carbonate is indicated to restore and maintain normocalcemia when hypocalcemia is not severe enough to warrant rapid replacement. It is used orally as supplementation to intravenous calcium therapy. Calcium carbonate moderates nerve and muscle performance by regulating the action potential excitation threshold. Amounts of elemental calcium in calcium carbonate tablets are as follows: Tums, 200 mg; Rolaids, 220 mg; Os-Cal, 500 mg.

Calcium citrate (Calcitrate, Cal-Citrate 225, Cal-Cee)

Calcium citrate is an oral formulation usually used as supplementation to intravenous calcium therapy. Calcium moderates nerve and muscle performance by regulating the action potential excitation threshold and facilitating normal cardiac function. Give the amount needed to supplement dietary intake so as to reach recommended daily amounts. The amount of elemental calcium in 1000 mg of calcium citrate is 210 mg.

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Fat-Soluble Vitamins

Class Summary

Low calcium levels may be treated with vitamin D supplements and calcium to restore the normal calcium balance. These medications are continued until parathyroid function improves. If parathyroid function does not improve with time, the patient may need lifelong calcium medication.

Ergocalciferol (Calciferol, Drisdol)

Ergocalciferol is the most widely available form of vitamin D. Ergocalciferol stimulates calcium and phosphate absorption from the small intestine and promotes calcium release from bone into the blood.

Cholecalciferol (Vitamin D3, Ddrops Kids, Delta-D3)

Cholecalciferol is a dietary supplement used to treat vitamin D deficiency or for prophylaxis.

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Beta-adrenergic Receptor Blockers

Class Summary

These agents reduce many of the symptoms of thyrotoxicosis, including tachycardia, tremor, and anxiety. Usually, propranolol is recommended because of central nervous system (CNS) penetration, but some patients prefer longer-acting beta blockers. Patients note an immediate improvement in tachycardia, anxiety, heat intolerance, and tremor.

These agents are used to reduce the risks of continued hyperthyroidism, including the development of perioperative thyroid storm (acute, life-threatening elevations of thyroid hormone levels).

Propranolol (Inderal, InnoPran XL)

This is the drug of choice in treating cardiac arrhythmias resulting from hyperthyroidism. It controls cardiac and psychomotor manifestations within minutes.

Atenolol (Tenormin)

Atenolol selectively blocks beta1 receptors, with little or no effect on beta2 types.

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Antithyroid Medications

Class Summary

These agents inhibit T4 and T3 synthesis and are used to reduce the risks of continued hyperthyroidism, including the development of perioperative thyroid storm (acute, life-threatening elevations of thyroid hormone levels).

Propylthiouracil

Propylthiouracil is a derivative of thiourea that inhibits organification of iodine by the thyroid gland. It blocks oxidation of iodine in the thyroid gland, thereby inhibiting thyroid hormone synthesis; the drug inhibits T4-to-T3 conversion (an advantage over other agents).

Propylthiouracil is available as a 50-mg tablet. It is readily absorbed and has a serum half-life of 1-2 hours. It is highly protein bound in the serum. The drug's duration of action is longer than its half-life, and propylthiouracil should be dosed every 6-8 hours (although it can be administered twice daily).

If patient compliance is an issue, methimazole is better choice because of daily dosing.

Thyroid hormone levels (TSH, T4, FTI or FT4, and T3) should be reassessed in 4 weeks and increased if thyroid hormone levels have not significantly fallen or decreased if thyroid hormone levels have fallen by 50% or more (even if still thyrotoxic). Usually, after thyroid function improves, the dose should be gradually decreased to 50-150 mg/d in divided doses (or the patient will become hypothyroid).

Methimazole (Tapazole)

Methimazole inhibits thyroid hormone by blocking oxidation of iodine in the thyroid gland. However, it is not known to inhibit peripheral conversion of thyroid hormone. The drug is available as 5-mg or 10-mg tablets. It is readily absorbed and has a serum half-life of 6-8 hours. Methimazole is less protein bound than propylthiouracil and is generally not used in pregnancy because of increased placental transfer and risk of a rare fetal condition (cutis aplasia). It has higher transfer rate into the milk of lactating women.

Methimazole's duration of action is longer than its half-life, and the drug should be dosed every 12-24 hours. Studies have shown that rectal suppositories or retention enemas can be used at the same dose as orally administered methimazole for patients who cannot take oral medications. Usually, after thyroid function improves, the dose must be decreased, or patient will become hypothyroid.

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