Urinary Iodine Concentrations Should Be Monitored to Diagnose Some Thyroid Gland Diseases in Heart Transplant Recipients

Background

According to the World Health Organization, iodine excreted in urine is a measure of its supply. According to the International Council for Control of Iodine Deficiency Disorders (ICCIDD), the urinary iodine (UI) should be >100 μg I per 1 liter of urine. Severe deficiency (SID) is diagnosed when UI is <50 μg/L and a moderate deficiency (MID) when UI is <100 μg/L.

Materials and Methods

UI analysis among 32 heart transplant recipients (26 men and 6 women); of overall mean age of 50.4 ± 12.6 years was performed using the modified Program Against Micronutrient Malnutrition method, a spectrophotometric measurement based on the Sandell-Kolthoff reaction. Results were compared with those of thyroid stimulating hormone (TSH; μIU/mL), of free tri-iodothyronine (FT3; pg/mL), and thyroxine (FT4; ng/dL).

Results

The average UI among the whole group was 126.4 ± 109.6 μg/L. SID occurred in 12 patients (37.5%) and MID in 4 (12.5%); namely, mean UI of 17.0 ± 9.6 and 79.5 ± 5.6, respectively. In the other 16 patients (50%), the average UI was high, namely, 220.1 ± 72.1 IU/mL. TSH, FT3, and FT4 in the whole group were within normal ranges. However, FT4 values significantly differed when SID and MID patients were compared with those displaying the recommended UI: 0.8 ± 0.2 and 0.9 ± 0.1 versus 1.1 ± 0.2 respectively (P < .05). We noted decreased values of TSH in 5 patients (15.6%) and of FT3 or FT4 in 6 subjects (18.8%).

Conclusion

There exists significant iodine deficiency among heart transplant recipients. Measurements of urinary iodine together with thyroid gland hormones may be essential to prevent thyroid gland disturbances in these patients.