[Thyroid gland ultrasound and urinary iodine excretion in children and adolescents with type I diabetes mellitus].

Background: Date, studies on thyroid volume and urinary iodide excretion in patients with diabetes mellitus are not available. Sonographically determined parameters of the thyroid size are correlated to other anthropometrous data and the urinary iodide excretion is correlated to glucosuria, the HbA1c value and the diabetes duration.

Method: In this prospective study we evaluated sonographically the thyroid volume in 107 patients with type I diabetes mellitus and 112 healthy children. The urinary iodide excretion was measured photometrically by using a modified ceric ion arsenious acid method for spontaneous urinary specimen and if available for the 24 h collected urin.

Results: The thyroid volume depended on site and age. A positive correlation of the thyroid volume and age, body weight and height, could be demonstrated. Referring to reference data a goitre prevalence of 30% in juvenile patients with diabetes mellitus type I was detected. Interestingly, juvenile type I diabetics presented with an average urinary iodide excretion of 183.0 micrograms iodide/g creatinine. Even the urinary iodide excretion of 162.5 micrograms iodide confirmed this increased level. The urinary iodide excretion in 24 hours correlated with glucosuria and the HbA1c level. The healthy children presented with an average urinary iodide excretion of 42.6 micrograms iodide/g creatinine. The mean value was clearly below the WHO recommendation of 150-300 micrograms iodide/g creatinine. Only 2.8% of the healthy children examined exceeded the lower limit of this range.

Conclusion: In addition to the existing distinct under supply of iodide we assume an increased urinary iodide excretion in context with the osmotic diuresis in juvenile diabetics. Contrary to current opinion, that these data are correlated to the daily intake of iodide, which was calculated from urinary excretion rate, this thesis could not be affirmed for juvenile diabetics. Therefore it seems reasonable to frequently control thyroid volume and thyroid function in children and adolescents with diabetes mellitus.