Pteridines (Nov 1993)
Neopterin Levels In Thyroid Pseudocysts
Abstract
Cystic changes of the thyroid remain a diagnostic dilemma with regard to malignancy due to insufficient information gained by fine needle aspiration, sonography and routine nuclear medicine procedures. As complementary soluble parameters we measured neopterin and thyroglobin levels in cyst fluids and in serum of 81 patients with disorders of the thyroid. Based on clinical, cytological and histological information, patients were divided into five groups. (I): Serous cysts (n=41), (II): hemorrhagic cysts (N=18), (III): cysts ' with evidence for inflammation clinically or by histology (n= 11), (IV): malignancy in cysts by histology (n = 6), (V): cysts containing "honey" like, brownish fluid of high viscosity (n = 5). Neopterin concentration in cyst fluids vs. serum in group (I) were not different, 8.8± 4.3 nmol/l in vs. 6.67± 3.34 nmol/l. In groups II-V neopterin concentration in cysts were higher than in serum, (II): 21.1 ± 18.7 nmol/l vs. 5.6± 2.56 nmol/l, (III): 30.6± 24.9 nmol/l vs. 6.1 ± 2.9 nmol/l, in (IV): 35± 23.5 vs. 10.98± 7.0 nmol/l and (V): 36.0± 23.9 vs. 5.9± 3.32 nmol/l respectively. In patients with proven benign histology at surgery, neopterin levels in cystic fluid were significantly lower than in cysts harbouring malignancy, 8.5±4.6 vs. 35.4±23.5 (Z=3,17, p=O. 0015). There were no significant differences between groups II, III IV and V regarding neopterin concentrations in cysts. Elevated serum neopterin levels were observed in 2/6 patients with aggressive thyroid cancer (group IV). However, average neopterin concentrations in serum of patients of group IV were not higher than in 15 patients from group I with benign histology (P=O.l). Significantly lower levels of thyroglobin in cyst fluid were found in group V ("honey" cysts) in comparison to all other groups pooled, 2.67± 1.82 f..lg/rnl vs. 6.76± 3.97 f..lg/ml, (Z=2.l5, p=0.031), four of five cysts in group V resolved after fine needle aspiration. We found no correlation between thyroglobin levels in cyst fluid and in serum.
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