From the Literature: Hyperthyroidism

Review highlights from three recent studies looking at pulomnary embolism in hyperthyroidism, undiagnosed thyroid disease, and thyrotoxicosis-related seizures.

Increased Risk of Pulmonary Embolism among Patients with Hyperthyroidism: A Five-Year Follow-up Study

Journal: Journal of Thrombosis and Haemostasis (July 14, 2010)

Authors: Lin H, Yang L, Kang J

Purpose: “Although studies have indicated that hyperthyroidism is associated with hypercoagulability, most such studies have focused only on examining the incidence and prevalence of venous thrombosis,” while none have explored “the risk of pulmonary embolism among patients with hyperthyroidism.”

Results: By comparing 8,903 patients with and 44,515 without hypethyroidism, researchers observed that 14 hyperthyroidism patients (0.16%) and 41 controls (0.08%) had pulmonary embolism during the follow-up period, and “after adjusting for geographic region, monthly income, hypertension, diabetes, hyperlipidemia, peripheral vascular disease, coronary heart disease cancer, recent surgery, recent fracture, pregnancy and the use of anticoagulants, the hazard of having PE during the five-year follow-up period was 2.31 times greater…for patients with hyperthyroidism than for patients in the comparison cohort.” The authors stress that “clinicians should be aware of this increased risk.”

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The Prevalence of Undiagnosed Thyroid Disease in Patients with Symptomatic Vocal Fold Paresis

Journal: Journal of Voice (August 21, 2010)

Authors: Heman-Ackah Y, Joglekar S, Caroline M, et al

Purpose: Because “the incidence of thyroid-related neuropathy in the larynx has not been previously described,” researchers sought to investigate “the prevalence of previously undiagnosed thyroid disease in patients with laryngeal neuropathy and to compare this prevalence with that in a cohort of patients with a neurotologic neuropathy.”

Results: After reviewing the “charts of 308 consecutive patients with dysphonia and vocal fold paresis and 333 consecutive patients with sensorineural hearing loss,” the authors found that “thyroid abnormalities are more prevalent in patients with dysphonia and vocal fold paresis (47.4%) than in patients with sensorineural hearing loss (16.5%).” This, they say, suggests “a greater association between previously undiagnosed thyroid abnormalities and laryngeal neuropathy than that between neurotologic neuropathy and thyroid disease.”

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The Prevalence of Thyrotoxicosis-Related Seizures

Journal: Thyroid (September 8, 2010)

Authors: Song T, Kim S, Kim G, et al

Purpose: Because “central nervous system dysfunction…may occur in patients with thyrotoxicosis,” and “seizures attributed to thyrotoxicosis” have been reported, the authors wanted “to determine prevalence of seizures that appeared to be related to the thyrotoxic state in patients with thyrotoxicosis.”

Results: Only seven of 3,382 patients with seizures met the authors’ criteria, and after becoming euthyroid, all EEGs were normal. No patient had a seizure during the 18-24 month follow-up period. “The prevalence of thyrotoxicosis-related seizures reported here can be used in conjunction with the prevalence of thyrotoxicosis in the population to estimate the prevalence of thyrotoxicosis-related seizures in populations.”

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