treat thyroid storm in pregnant patients

Thyroid storm is a life-threatening condition characterized by end-organ dysfunction and has reported in-ICU and 6-month mortality rates of 17% and 22%, respectively. Clinicians must have a high index of suspicion to identify and initiate treatment rapidly to prevent further decompensation. The Burch-Wartofsky clinical scoring tool is often used to differentiate thyroid storm from symptomatic hyperthyroidism, with a score >45 being highly suggestive of thyroid storm and a score <25 making thyroid storm unlikely. Burch-Wartofsky criteria include body temperature, cardiovascular dysfunction (tachycardia, atrial fibrillation, congestive heart failure), neurological status, signs of GI-hepatic dysfunction, and presence of triggering events.

This patient has a Burch-Wartofsky score of 55 (degree of tachycardia, fever of 39.2°C, and agitation) meeting clinical criteria for thyroid storm, which was likely precipitated by the stress of her pregnancy. Initial management of patients critically ill with thyroid storm is guideline driven and includes administration of a thionamide, β-adrenergic blockade, and glucocorticoids. Both propylthiouracil (PTU) and methimazole (MMI) are thionamides used to treat thyroid storm; however, PTU is preferred in the first trimester (13 weeks) because of the possible teratogenic potential of MMI.

Thionamides, such as PTU and MMI, inhibit the synthesis of thyroid hormone within 1 to 2 h of administration but do not prevent the release of thyroid hormone already produced. PTU also blocks peripheral conversion of thyroxine (T4) to the more biologically active hormone, triiodothyronine (T3), leading to its preferential use in patients who are critically ill due to thyroid storm.

β-Blockade should be started immediately (unless contraindicated) to prevent the deleterious adrenergic effects of thyroid hormone excess. Propranolol is the preferred β-adrenergic blocking agent because it inhibits type 1 deiodinase, which may prevent peripheral T4-to-T3 conversion, thus decreasing serum T3 levels. It can be administered intravenously, and it is relatively short acting. Likewise, glucocorticoids decrease T4-to-T3 conversion and have been associated with improved outcomes in patients with thyroid storm.

Iodine-containing solutions, such as saturated solution of potassium iodide, block the release of T4 and T3 from the thyroid gland; however, it should be administered at least 1 h after the patient receives a thionamide so that the iodine cannot be used for thyroid hormone synthesis.

Thyroidectomy has a limited role in the acute management of thyroid storm. The patient should be hemodynamically stable before consideration of thyroidectomy. Thyroidectomy is an option to treat Graves disease definitively but should not be pursued until the patient is no longer acutely ill.123456

Footnotes

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  3. Carroll R, Matfin G. Endocrine and metabolic emergencies: thyroid storm. Ther Adv Endocrinol Metab. 2010;1(3):139-145. PubMed ↩

  4. Chattaway JM, Klepser TB. Propylthiouracil versus methimazole in treatment of Graves’ disease during pregnancy. Ann Pharmacother. 2007;41(6):1018-1022. PubMed ↩

  5. Moleti M, Di Mauro M, Sturniolo G, et al. Hyperthyroidism in the pregnant woman: maternal and fetal aspects. J Clin Transl Endocrinol. 2019;16:100190. PubMed ↩

  6. Ross DS, Burch HB, Cooper DS, et al. 2016 American Thyroid Association guidelines for diagnosis and management of hyperthyroidism and other causes of thyrotoxicosis. Thyroid. 2016;26(10):1343-1421. PubMed ↩