Relation of thyroid hormones with the total and specific serum activity of N-acetyl-beta-D-glucosaminidase.

C Pinto, A Galvão-Teles, C Marques, C Manso


Total serum N-acetyl-beta-D-glucosaminidase (NAG), isoenzyme A (labile) and isoenzyme B (stable) activities were determined in euthyroid controls and in thyroid disease. In twenty hyperthyroid individuals total NAG (856.9 +/- 122,676 nmols/h/ml and isoenzyme A (490.3 +/- 93.592) as well as isoenzyme B (361.6 +/- 66,371), were higher than the levels in nineteen hypothyroid [total NAG = 533.105 +/- 97.927 (p less than 0.001); isoenzyme A = 280.263 +/- 61.463 (p less than 0.001); isoenzyme B = 251,580 +/- 50,530 (p less than 0.001)] or in twenty euthyroid [total NAG = 555.55 +/- 75.59 (p less than 0.001); isoenzyme A = 316.85 +/- 55.0 (p less than 0.001); isoenzyme B = 238.95 +/- 39.60 (p less than 0.001)]. Monthly assays were performed in seven hypothyroid and eleven hyperthyroid over the course of their corrective treatment with L-thyroxine (LT4: 0.1-0.2 mg (day) and propylthiouracil (PTU: 0.3-0.4/day), respectively. Total T4 was taken as the criterion for thyroid status. The reduction of hormone activity in seven hyperthyroid was accompanied by a significant decrease in enzyme activity (NAG = p less than 0.02; isoenzyme A = p less than 0.02). Isoenzyme B displayed no significant variation. In four hyperthyroid submitted to treatment with PTU there was no reduction in NAG activity and although T4 came down to normal levels. These patients still displayed symptoms of hyperthyroidism.(ABSTRACT TRUNCATED AT 250 WORDS)

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