抄録
Urinary N-acetyl-β-D-glucosaminidase (NAG) activity was measured longitudinally in 12 patients with Graves' disease, 5 patients with subacute thyroiditis, and 1 patient with silent thyroiditis, and compared with that of 36 normal controls. The patients with Graves' disease and subacute thyroiditis were treated with anti-thyroid drug (methimazole or propylthiouracil) and prednisolone, respectively. On the other hand, no treatment was given to the patient with silent thyroiditis. Since two patients with Graves' disease clearly showed transient deterioration of the thyroid function during the treatment period, data from these two patients were separately investigated. Urinary levels of NAG in the remaining ten patients with Graves' disease before, 1, 3, 6 and 12 months after the treatment were 15.59±7.93 (SD), 8.96±6.82, 4.39±2.33, 3.46±2.24, and 3.63±2.38 U/g.creatinine (g.Cr.), respectively. Those obtained before, 1 and 3 months after the treatment were significantly higher than those of the controls (2.85± 1.12 U/g.Cr.). Free thyroid hormone levels became normal or low 3 months after the treatment. The two Graves' patients mentioned above showed a transient increase in urinary NAG with concomitant changes in free thyroid hormone levels. Urinary NAG levels in the patients with subacute thyroiditis before, 2, 4, and 6 weeks after the treatment were 16.56± 10.97, 6.76±2.79, 3.14±0.48 and 3.70± 1.44 U/g.Cr., respectively. Those obtained before and 2 weeks after the treatment were significantly higher than those of the controls. Free thyroid hormones were normal 2 weeks after therapy. Urinary NAG in the patient with silent thyroiditis was 9.60 U/g.Cr. on the first visit and gradually decreased. Urinary NAG was still high 1 month after the first consultation while thyroid function became normal. A positive correlation between the levels of urinary NAG and free thyroid hormones was also observed in each group. These results indicate that excessive thyroid hormones may induce urinary excretion of NAG and the fall in serum thyroid hormone levels precedes that in the urinary NAG level. The present results also suggest that urinary NAG activity is a useful tool to use in assessing thyroid function in patients with thyroid disorder.
