A clinical retrospective analysis of factors associated with apathetic hyperthyroidism.

OBJECTIVE Apathetic hyperthyroidism can be misdiagnosed or diagnosed late, and older patients are often susceptible to adverse effects of treatment for thyrotoxicosis. The aim of this study was to identify factors associated with apathetic hyperthyroidism. METHODS We retrospectively examined serum calcium, phosphorus and bone-specific alkaline phosphatase (BAP) levels and thyroid-associated variables in 140 patients with apathetic hyperthyroidism, 456 patients with typical hyperthyroidism and 120 healthy subjects. RESULTS Significant differences were identified with respect to age, serum calcium and corrected calcium, serum phosphorus, thyroid-stimulating hormone (TSH), free triiodothyronine (FT(3)), free thyroxine (FT(4)), the FT(3)/FT(4) ratio, alanine aminotransferase (ALT), aspartate aminotransferase (AST), creatinine, BAP and albumin among the typical and apathetic hyperthyroid and normal groups (all p < 0.001). Univariate logistic regression showed that age, serum calcium and corrected calcium, serum phosphorus, TSH, FT(4), FT(3)/FT(4) ratio, ALT, AST and BAP were significantly associated with apathetic hyperthyroidism, and multivariate logistic regression showed that age, corrected calcium, TSH, FT(4), FT(3)/FT(4) ratio, BAP and ALT were significantly associated with apathetic hyperthyroidism. CONCLUSION Greater age, increased corrected calcium levels, decreased TSH levels, increased FT(4), a decreased FT(3)/FT(4) ratio, increased BAP levels and increased ALT levels may be significant factors for differentiating apathetic from typical hyperthyroidism. Coordinated assessment of these variables may aid in the accurate diagnosis and treatment of this disorder.