| pubmed-article:3310836 | pubmed:abstractText | The physiological variations in serum TSH concentration have been investigated using an enzyme amplified immunoassay with improved sensitivity and precision. Blood samples were collected at regular intervals from 10 healthy volunteers during the period 1800 h to 0100 h. Spectral analysis followed by periodic regression analysis demonstrated significant serum TSH pulsatility with periodicities of 60 or 85-100 min. In addition, a significant (P less than 0.001) evening rise in serum TSH concentration was demonstrated in all subjects, with levels rising at around 21.30-22.00 h. | lld:pubmed |
