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Thyrotropin Secretion by Thyrotropinomas Is Characterized by Increased Pulse Frequency, Delayed Diurnal Rhythm, Enhanced Basal Secretion, Spikiness, and Disorderliness

Department of Endocrinology and Metabolic Diseases (F.R., A.M.P., J.AR.), Leiden University Medical Center, NL2333ZA Leiden, The Netherlands; Department of Statistics (D.M.K.), University of Virginia, Charlottesville, Virginia 22904; and Endocrine Research Unit (J.D.V.), Mayo Medical and Graduate Schools, Clinical Translational Research Center, Mayo Clinic, Rochester, Minnesota 55905

Address all correspondence and requests for reprints to: Ferdinand Roelfsema, Department of Endocrinology and Metabolism, Leiden University Medical Center, Albinusdreef 2, NL2333ZA Leiden, The Netherlands. E-mail: f.roelfsema{at}lumc.nl.

Context: Hormone secretion by somatotropinomas, corticotropinomas, and prolactinomas exhibits increased pulsatility and basal secretion, accompanied by greater disorderliness.

Objective: Our objective was to evaluate TSH secretion by thyrotropinomas with up-to-date analytical and mathematical tools.

Design: Twenty-four hour blood samplings at 10-min intervals in a clinical research laboratory in five patients with a thyrotropinoma and 10 healthy age- and gender-matched controls were performed. The obtained serum TSH profiles were analyzed with a new deconvolution method, approximate entropy, Cosinor analysis, and by quantification of spikiness.

Results: TSH burst frequency and basal secretion were increased in patients compared with controls. TSH secretion patterns in patients were more irregular than in controls, but the diurnal rhythm was preserved at a higher mean in all patients, although with a 2-h phase delay.

Conclusion: TSH secretion by thyrotropinomas shares many characteristics with other pituitary hormone-secreting adenomas.