Preferential Renal Excretion of Iodide Derived from Thyroxine and Triiodothyronine Deiodination in Man

Shimoda, Shin-Ichi; Kasai, Kikuo; Kikuchi, Toshinori; Ieiri, Tamio

doi:10.1210/jcem-44-1-137

Cited by 2 publications

(1 citation statement)

References 5 publications

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“…Yet, certain patients be prescribed T4 for non-thyroid indications, such as treatment for fatigue or obesity [55]. Deiodination of T4 following ingestion and metabolism (average dosage ~125 µg) likely results in its preferential renal excretion as iodide [56] that increases UIE to a greater extent than typical food sources of iodine in the Canadian diet. However, simultaneous intake of T4 and iodine supplements is not recommended given concerns of excessive iodine intake with potential risks for hyperthyroidism.…”

Section: Iodine Nutritional Status Of Canadian Adultsmentioning

confidence: 99%

The Prevalence and Risk Factors Associated with Iodine Deficiency in Canadian Adults

et al. 2022

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Iodine is a trace micronutrient that is critical for normal thyroid function and human health. Inadequate dietary intake is associated with cognitive impairment, infertility, growth retardation and iodine deficiency disorders in affected populations. Herein, we examined the prevalence of iodine deficiency in adults (median age of 61 years) based on the analysis of 24 h urine samples collected from 800 participants in four clinical sites across Canada in the Prospective Urban and Rural Epidemiological (PURE) study. Urinary iodide together with thiocyanate and nitrate were measured using a validated capillary electrophoresis assay. Protective/risk factors associated with iodine deficiency were identified using a binary logistic regression model, whereas daily urinary iodine concentration (24 h UIC, μg/L) and urinary iodine excretion (24 h UIE, μg/day) were compared using complementary statistical methods with covariate adjustments. Overall, our Canadian adult cohort had adequate iodine status as reflected by a median UIC of 111 μg/L with 11.9% of the population <50 μg/L categorized as having moderate to severe iodine deficiency. Iodine adequacy was also evident with a median 24 h UIE of 226 μg/day as a more robust metric of iodine status with an estimated average requirement (EAR) of 7.1% (< 95 μg/day) and a tolerable upper level (UL) of 1.8% (≥1100 μg/day) based on Canadian dietary reference intake values. Participants taking iodine supplements (OR = 0.18; p = 6.35 × 10−5), had greater 24 h urine volume (OR = 0.69; p = 4.07 × 10−4), excreted higher daily urinary sodium (OR = 0.71; p = 3.03 × 10−5), and/or were prescribed thyroxine (OR = 0.33; p = 1.20 × 10−2) had lower risk for iodine deficiency. Self-reported intake of dairy products was most strongly associated with iodine status (r = 0.24; p = 2.38 × 10−9) after excluding for iodine supplementation and T4 use. Participants residing in Quebec City (OR = 2.58; p = 1.74 × 10−4) and Vancouver (OR = 2.54; p = 3.57 × 10−4) were more susceptible to iodine deficiency than Hamilton or Ottawa. Also, greater exposure to abundant iodine uptake inhibitors from tobacco smoking and intake of specific goitrogenic foods corresponded to elevated urinary thiocyanate and nitrate, which were found for residents from Quebec City as compared to other clinical sites. Recent public health policies that advocate for salt restriction and lower dairy intake may inadvertently reduce iodine nutrition of Canadians, and further exacerbate regional variations in iodine deficiency risk.

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Section: Iodine Nutritional Status Of Canadian Adultsmentioning

confidence: 99%

The Prevalence and Risk Factors Associated with Iodine Deficiency in Canadian Adults

et al. 2022

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Thyroid Function Studies in the Nephrotic Syndrome

Afrasiabi¹

1979

Ann Intern Med

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Total serum and urinary thyroxine (T4), triiodothyronine (T3), and thyroxine-binding globulin (TBG) as well as serum free T4, thyroid-stimulating hormone (TSH), and T3 resin uptake (T3RU) were measured in seven patients with the nephrotic syndrome. The nephrotic syndrome was defined by proteinuria exceeding 3 g/24 h. All patients were clinically euthyroid. Most values for total serum T4, free T4, T3, T3RU, TBG, and TSH were within normal limits. However, the mean serum T3 and TBG values were significantly lower in patients compared with the control group. The values (mean +/- 2 SD) for urinary T4 were 24.3 +/- 20.3 in the patient group and 1.5 +/- 0.7 microgram/24 h in the control group. Urinary T3 values for patients and the control group were 2100 +/- 856 and 848 +/- 253 ng/24 h respectively. Urinary TBG was 2.1 +/- 1.8 mg/24 h in the patients and undetectable in the control group. There was no correlation between daily urinary T3 and T4 and urinary TBG. There was a weak correlation between daily urinary protein excretion and urinary T4 (r = 0.5).

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Preferential Renal Excretion of Iodide Derived from Thyroxine and Triiodothyronine Deiodination in Man

Cited by 2 publications

References 5 publications

The Prevalence and Risk Factors Associated with Iodine Deficiency in Canadian Adults

The Prevalence and Risk Factors Associated with Iodine Deficiency in Canadian Adults

Thyroid Function Studies in the Nephrotic Syndrome

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