[Thyroid function in depressed patients]

This preliminary report compares the FT3, FT4, TSH basal levels and FT4/FT3 ration of depressed patients (DSM III-R criteria) with those of a healthy control group. Authors have also studied thyroid parameters in function of some clinical depression data (polarity, intensity and endogenous character) and other factors as age and sex. 81 depressed patients (31 men, 50 women), with mean age of 44.85 years were studied. 44 patients suffered of an endogenous depression and 37 of a non endogenous depression (Newcastle criteria). 60 patients had an unipolar depression while 21 patients had a bipolar depression. The control group was constituted of 36 healthy subjects (20 men, 16 women), with mean age of 40.94 years. There is no significant difference between the two groups for sex and age, besides the different size of the two groups. FT3 mean of depressed patients was 4.39 pmol/l. There was a significant difference between unipolar group FT3 mean (4.51 +/- 1.01 pmol/l) and bipolar FT3 mean (4.03 +/- 0.91 pmol/l; t = 2.02, p < 0.05). Depression intensity was correlated negatively to FT3 mean (r = -0.23; t = 2.10, p < 0.005). FT4 mean in the depressed group was 12.62 +/- 4.14 pmol/l. The only significative result for FT4 was its correlation to TSH levels (r = -0.36; t = 3.43, p < 0.001). TSH mean in depressed patients was 1.43 +/- 0.85 microIU/ml. When we have compared these results with those of control group we concluded that FT3 and TSH levels were significantly lower in the depressed group (FT3: t = 4.83, p < 0.0001; TSH; t = 2.44 p < 0.02) and that FT4 was slightly but not significantly increased in the depressed group. FT3 decrease and the slight FT4 increase in depression may be the consequence of a metabolic deviation of FT4 transformation into FT3. Its link with intensity and polarity of depression suggests that it can be considered as a biological marker of this disease.