Urinary glycosaminoglycans in Graves' ophthalmopathy

An increased accumulation of glycosaminoglycans (GAG) in retrobulbar tissues has been reported in patients with thyroid eye disease. We examined the quantitative urinary GAG excretion in 101 patients with Graves' ophthalmopathy of different classes, 36 patients with Graves' hyperthyroidism without ophthalmopathy, 14 patients with toxic nodular goitre and 103 control subjects. Glycosaminoglycans were isolated from 24-h urine collections by precipitation with cetylpyridinium chloride and ethanol followed by photometrical quantification of hexuronic acids after reaction with carbazole. In comparison with the control group (15.8, 10.4, 21.6 mg/24 h; median, 25th, 75th percentile) a significant (P less than 0.005) elevation of urinary GAG excretion was found in patients with ophthalmopathy (19.2, 12.2, 28.7 mg/24 h), whereas patients with Graves' hyperthyroidism and no ophthalmopathy (16.2, 11.9, 21.7 mg/24 h) and patients with toxic nodular goitre (15.8, 11.5, 21.2 mg/24 h) exhibited no markedly increased values. Especially, patients with active, untreated ophthalmopathy showed on average a twofold increase (36.7, 28.1, 48.4 mg/24 h) in urinary GAG excretion. In contrast, high values were not found in patients with inactive ophthalmopathy and elevated values decreased under treatment, which correlated with clinical findings. Further, relapses were also accompanied by high GAG excretion. Thus, using a simple laboratory method, quantitative determination of urinary GAG excretion appears to present an effective parameter for the activity of Graves' ophthalmopathy.