Plasma leptin concentrations in patients with Graves' disease with or without ophthalmopathy

Recent studies have demonstrated that human preadipocyte fibroblasts in orbital connective tissues from patients with Graves' ophthalmopathy differentiate into cells resembling adipocytes and acquire expression of leptin and functional thyroid stimulating hormone receptors. These finding imply that leptin may play a role in the pathogenesis of Graves' ophthalmopathy. However, little is known about plasma leptin concentration in patients with Graves' disease with or without ophthalmopathy.

To investigate this relationship; 28 patients with active Graves' ophthalmopathy (19 female and 9 male, mean age: 32.7+/-10.5 years, mean BMI: 24.8+/-3.7 kg/m2) and 10 patients without ophthalmopathy (6 female and 4 male, mean age: 24.6+/-5.6, mean BMI: 23.02+/-2.4 kg/m2) all with untreated Graves' disease were included in the study at first diagnosis in our endocrinology out-patient clinic. Sex-, BMI- and age-matched twenty healthy subjects (13 female, 7 male, mean age: 31.9+/-10.0, mean BMI: 24.2+/-3.0 kg/m2) were selected as a control group. Plasma leptin levels were measured by a RIA method with a sensitivity of 0.5 ng/ml.

Results showed any significant differences neither between patients and controls (7.97+/-5.2 ng/ml vs. 7.83+/-3.7 ng/ml) nor between patients with or without Graves' ophthalmopathy (8.29+/-5.0 ng/ml vs. 7.06+/-5.8 ng/ml) (both P>0.05). Moreover, no correlation was found between plasma leptin levels and ophthalmopathy index score, or proptosis.

Although effects of local leptin production in the orbit cannot be excluded, our data suggest that circulating plasma leptin does not have a significant direct influence on ophthalmopathy index score or pathophysiology of Graves' ophthalmopathy.