The 24-hour pattern of serum TSH in patients with endogenous depression.

The 24-h pattern of serum thyrotropin (TSH) has been studied using hourly blood-sampling in four patients with severe endogenous depression. All patients showed a pattern similar to that of normal subjects, with lowest levels of serum TSH between 0900 and 2000 h and highest levels between 2100 and 0800 h. A phaseshift of the TSH rhythm can therefore not account for our previous finding of a significant negative correlation between severity of endogenous depression and night increase in serum TSH measured as the difference between the values at 2400 and 1400 h.