TY - JOUR
T1 - Diminished and irregular thyrotropin secretion with preserved diurnal rhythm in patients with active acromegaly
AU - Roelfsema, Ferdinand
AU - Biermasz, Nienke R.
AU - Frolich, Marijke
AU - Keenan, Daniel M.
AU - Veldhuis, Johannes D.
AU - Romijn, Johannes A.
PY - 2009/6
Y1 - 2009/6
N2 - Context: The hypothalamo-pituitary-thyroid axis in acromegaly may be altered. Previous studies report diminished serum TSH concentrations in patients with active acromegaly and decreased response to TRH. On the other hand, most patients have normal thyroid hormone concentrations. Objective: Our aim was to analyze serum TSH profiles in relation to GH profiles in patients with untreated acromegaly, in order to delineate aberrations in the hypothalamo-pituitary- thyroid system. Intervention: Twenty-one patients with active acromegaly and matched controls underwent a 24-h, 10-min blood sampling study. GH and TSH data were analyzed with a newly developed automated deconvolution program, approximate entropy, and cosinor regression. Results: Basal (10.4 ± 2.0 vs. 13.8 ± 1.4 mU/liter·24 h; P = 0.02) and pulsatile (11.4 ± 1.7 vs. 18.6 ± 1.6 mU/liter·24 h; P = 0.002) TSH secretion was decreased in patients. TSH secretory regularity was diminished with loss of pattern synchrony between TSH and GH. Total TSH secretion correlated with TSH increase after TRH (R = 0.75; P = 0.0001), negatively with the log-transformed GH secretion rate (R = -0.52; P = 0.001), but not with adenoma size. The diurnal TSH rhythm was preserved. Total and free T4 concentrations were similar in patients and controls. Conclusion: Basal and pulsatile TSH secretion is decreased in active acromegaly, although T 4 levels are unaffected. Diminished TSH secretion is compatible with enhanced restraint by tumoral GH feedback-driven somatostatin outflow, explaining also the reduced regularity of TSH secretion. Unchanged T4 concentrations might reflect decreased sympathetic function in GH excess states, heightening responsiveness of the thyroid gland to TSH.
AB - Context: The hypothalamo-pituitary-thyroid axis in acromegaly may be altered. Previous studies report diminished serum TSH concentrations in patients with active acromegaly and decreased response to TRH. On the other hand, most patients have normal thyroid hormone concentrations. Objective: Our aim was to analyze serum TSH profiles in relation to GH profiles in patients with untreated acromegaly, in order to delineate aberrations in the hypothalamo-pituitary- thyroid system. Intervention: Twenty-one patients with active acromegaly and matched controls underwent a 24-h, 10-min blood sampling study. GH and TSH data were analyzed with a newly developed automated deconvolution program, approximate entropy, and cosinor regression. Results: Basal (10.4 ± 2.0 vs. 13.8 ± 1.4 mU/liter·24 h; P = 0.02) and pulsatile (11.4 ± 1.7 vs. 18.6 ± 1.6 mU/liter·24 h; P = 0.002) TSH secretion was decreased in patients. TSH secretory regularity was diminished with loss of pattern synchrony between TSH and GH. Total TSH secretion correlated with TSH increase after TRH (R = 0.75; P = 0.0001), negatively with the log-transformed GH secretion rate (R = -0.52; P = 0.001), but not with adenoma size. The diurnal TSH rhythm was preserved. Total and free T4 concentrations were similar in patients and controls. Conclusion: Basal and pulsatile TSH secretion is decreased in active acromegaly, although T 4 levels are unaffected. Diminished TSH secretion is compatible with enhanced restraint by tumoral GH feedback-driven somatostatin outflow, explaining also the reduced regularity of TSH secretion. Unchanged T4 concentrations might reflect decreased sympathetic function in GH excess states, heightening responsiveness of the thyroid gland to TSH.
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U2 - 10.1210/jc.2009-0174
DO - 10.1210/jc.2009-0174
M3 - Article
C2 - 19336512
AN - SCOPUS:66749106892
VL - 94
SP - 1945
EP - 1950
JO - Journal of Clinical Endocrinology and Metabolism
JF - Journal of Clinical Endocrinology and Metabolism
SN - 0021-972X
IS - 6
ER -