The Prevalence of Thyroid Dysfunction in Elderly Cardiology Patients with Mild Excessive Iodine Intake in the Urban Area of São Paulo

Abstract

Duarte GC, Tomimori EK, Camargo RYA, Rubio IGS, Wajngarten M, Rodrigues AG, Knobel M, Medeiros-Neto G. The prevalence of thyroid dysfunction in elderly cardiology patients with mild excessive iodine intake in the urban area of São Paulo. Clinics. 2009;64:135-42. OBJECTIVES:To evaluate the prevalence of thyroid dysfunction in elderly cardiac patients in an outpatient setting. SUBJECTS AND METHODS: A total of 399 consecutive patients (268 women, age range 60-92 years) who were followed at Heart Institute were evaluated for thyroid dysfunction with serum free T4, TSH, anti-Peroxidase antibodies, urinary iodine excretion measurements and thyroid ultrasound. RESULTS: Hyperthyroidism (overt and subclinical) was present in 29 patients (6.5%), whereas hypothyroidism (overt and subclinical) was found in 32 individuals (8.1%). Cysts were detected in 11 patients (2.8%), single nodules were detected in 102 (25.6%), and multinodular goiters were detected in 34 (8.5%). Hashimoto's thyroiditis was present in 16.8% patients, most of whom were women (83.6%). The serum TSH increased with age and was significantly higher (p= <0.01) in patients, compared to the normal control group. No significant differences in serum TSH and free T4 values were observed when patients with atrial fibrillation (AF) where compared with those without arrhythmia. The median urinary iodine levels were 210 µg/L (40-856 µg/L), and iodine levels were higher in men than in women (p<0.01). Excessive iodine intake (urinary iodine >300 µg/L) was observed in one-third of patients (30.8%). CONCLUSIONS: Elderly patients have a higher prevalence of both hypo-and hyperthyroidism as well as thyroid nodules when compared with the general population. About one-third of the older patients had elevated urinary secretion of iodine and a higher prevalence of chronic Hashimoto's thyroiditis. It is recommended that ultrasonographic studies, tests for thyroid function and autoimmunity should be evaluated in elderly patients.

Prevalence of iodine intake inadequacy in elderly Brazilian women. A cross-sectional study

“…Nutritional status of iodine has been evaluated using urinary iodine quantification in addition to other indirect methods, such as hormonal dosage tests and ultrasound of the thyroid (1,5,8,11). Urinary iodine (UI) represents a good indicator of the recent ingestion of iodine, as 90% of ingested iodine is expelled through the urine (19).…”

“…In recent decades, the recommended maximum fortification of salt with iodine has varied between 60mg and 100mg of iodine/kg of salt, according to evidence regarding excesses or deficiencies of iodine (5-7). Although the current limit is 60mg/kg of salt (4), in certain regions of the country, excessive levels of urinary iodine have been reported in some groups of people, such as children (8), adults who live in metropolitan areas and people who have heart conditions (1,5). However, these findings do not represent all population groups and should not be generally extrapolated to the country's population.…”

Hipertensão arterial sistêmica secundária

“…7 A hipertensão arte rial sistêmica ocorre em 20% dos pacientes com hipotireoidismo. [8][9][10] O diagnóstico precoce é feito pela dosagem de TSH aumentado e confirmado com a diminuição gradativa de T4 livre.…”

TSH reference values for adult Brazilian population

“…Studies employing rigorous selection criteria, excluding subjects with thyroid disease not only based on clinical data but also on autoantibody measurement and ultrasonography (3), support this change. However, not all investigators agree with this change (4,5) and there are also careful studies reaffirming that the upper limit of normal TSH of about 3.5 to 4 mIU/L is adequate (6)(7)(8)(9)(10)(11)(12).…”