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Smaller thyroid volume related to higher TSH levels in euthyroid children
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In children with normal thyroid function, smaller thyroid volume appears to be linked to higher normal thyroid-stimulating hormone levels, according to recent findings.
In the analysis, researchers utilized data on 6,101 children enrolled in the KiGGS Study, a nationwide survey aimed at acquiring comprehensive and representative information on the health of German children and teenagers aged 0 to 17 years. The children were measured for BMI and body surface area, and the researchers also assessed iodine and creatinine concentrations through spot urine samples. Blood samples were taken and assayed for TSH, free triiodothyronine, free thyroxine and thyroid peroxidase antibody (TPO-Ab) levels.
Ultrasonography was used to determine thyroid volume in all children, and three different linear regression models were used to test the hypothesized correlations between urinary iodine status, TSH levels and thyroid volume. Children with potential pathophysiologies in any thyroid parameter were excluded from analysis.
The researchers found that after adjusting for sex, age, body surface area, BMI, free T3/free T4 ratio and time of blood sampling, there was a correlation between higher urinary iodine excretion and higher TSH levels (P<.05). There was no link between higher TSH concentration and higher incidence of TPO-Ab levels, but there was a correlation between higher TSH and lower thyroid volume (P<.001). There was no relationship found between spot measurements of urinary iodine and thyroid volume.
According to the researchers, these findings contradict traditional beliefs regarding iodine status and TSH levels.
“A decreased thyroid cell mass and cell amount, as induced by an improved iodine status, does presumably require a higher TSH signal to maintain a constant thyroid hormone production, suggesting an underlying physiological adaptation,” the researchers wrote. “Correspondingly, an increased TSH level should not be used as the single criterion to evaluate the prevalence of hypothyroidism, and the repeatedly observed parallel increases of iodine supply and TSH levels should not readily be interpreted as evidence for an increased hypothyroidism. The present results therefore shed some light on the ongoing and quite complex discussion on the effects of iodine nutrition on thyroid health.”
Disclosure: The researchers report no relevant financial disclosures.
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