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Seasonal variation of serum thyrotropin concentration and thyrotropin response to thyrotropin-releasing hormone in patients with primary hypothyroidism on constant replacement dosage of thyroxine.
J Clin Endocrinol Metab. 1982 Jun; 54(6):1118-24.JC

Abstract

Ten patients with primary hypothyroidism (aged 32--66 yr), replaced on constant daily doses of L-T4 (mean +/- SD, 1.90 +/- 0.22 micrograms/kg BW), were used to examine seasonal variations in serum levels of thyroid-related hormones for a period of 14 months. Basal and peak TSH concentrations after TRH (500 micrograms) were higher in winter than in summer. Summer values for basal TSH were all normal (normal range, less than 4.8 microU/ml), while winter values were supranormal in 5 of 10 patients. Summer values for peak TSH were subnormal or normal (normal range, 5.0--40.0 microU/ml), while winter values were supranormal in 3 patients, with the remaining values being normal [log basal TSH, 0.511 +/- 0.438 vs. 0.084 +/- 0.244 (P less than 0.05); log peak TSH, 1.394 +/- 0.410 vs. 1.017 +/- 0.423 (P less than 0.05)]. Serum resin T3 uptake, T4, free T4 index(FT4I), T3, free T3 index, and rT3 levels did not vary seasonally, although T4 and FT4I tended to fall in the winter. The summer and winter QKd interval (the interval from the onset of a QRS complex in the electrocardiogram to the appearance of the Korotkoff sound at diastolic pressure), basal metabolic rate, and serum cholesterol concentrations were all within the normal range. Basal and peak TSH after TRH were inversely correlated with serum T4 and FT4I levels. The basal TSH concentration was further inversely correlated with the seasonally altering ambient temperature. These results indicate that during the treatment of primary hypothyroidism with constant doses of T4, 1) serum TSH and its response to TRH show seasonal variation, 2) the hypersecretion TSH in the winter is related to small changes in serum T4 and FT4I levels, and 3) the seasonal variation in the serum TSH concentration may need to be taken into consideration when evaluating the adequacy of a T4 replacement dose.

Authors

No affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article

Language

eng

PubMed ID

6804476

Citation

Konno, N, and K Morikawa. "Seasonal Variation of Serum Thyrotropin Concentration and Thyrotropin Response to Thyrotropin-releasing Hormone in Patients With Primary Hypothyroidism On Constant Replacement Dosage of Thyroxine." The Journal of Clinical Endocrinology and Metabolism, vol. 54, no. 6, 1982, pp. 1118-24.
Konno N, Morikawa K. Seasonal variation of serum thyrotropin concentration and thyrotropin response to thyrotropin-releasing hormone in patients with primary hypothyroidism on constant replacement dosage of thyroxine. J Clin Endocrinol Metab. 1982;54(6):1118-24.
Konno, N., & Morikawa, K. (1982). Seasonal variation of serum thyrotropin concentration and thyrotropin response to thyrotropin-releasing hormone in patients with primary hypothyroidism on constant replacement dosage of thyroxine. The Journal of Clinical Endocrinology and Metabolism, 54(6), 1118-24.
Konno N, Morikawa K. Seasonal Variation of Serum Thyrotropin Concentration and Thyrotropin Response to Thyrotropin-releasing Hormone in Patients With Primary Hypothyroidism On Constant Replacement Dosage of Thyroxine. J Clin Endocrinol Metab. 1982;54(6):1118-24. PubMed PMID: 6804476.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Seasonal variation of serum thyrotropin concentration and thyrotropin response to thyrotropin-releasing hormone in patients with primary hypothyroidism on constant replacement dosage of thyroxine. AU - Konno,N, AU - Morikawa,K, PY - 1982/6/1/pubmed PY - 1982/6/1/medline PY - 1982/6/1/entrez SP - 1118 EP - 24 JF - The Journal of clinical endocrinology and metabolism JO - J Clin Endocrinol Metab VL - 54 IS - 6 N2 - Ten patients with primary hypothyroidism (aged 32--66 yr), replaced on constant daily doses of L-T4 (mean +/- SD, 1.90 +/- 0.22 micrograms/kg BW), were used to examine seasonal variations in serum levels of thyroid-related hormones for a period of 14 months. Basal and peak TSH concentrations after TRH (500 micrograms) were higher in winter than in summer. Summer values for basal TSH were all normal (normal range, less than 4.8 microU/ml), while winter values were supranormal in 5 of 10 patients. Summer values for peak TSH were subnormal or normal (normal range, 5.0--40.0 microU/ml), while winter values were supranormal in 3 patients, with the remaining values being normal [log basal TSH, 0.511 +/- 0.438 vs. 0.084 +/- 0.244 (P less than 0.05); log peak TSH, 1.394 +/- 0.410 vs. 1.017 +/- 0.423 (P less than 0.05)]. Serum resin T3 uptake, T4, free T4 index(FT4I), T3, free T3 index, and rT3 levels did not vary seasonally, although T4 and FT4I tended to fall in the winter. The summer and winter QKd interval (the interval from the onset of a QRS complex in the electrocardiogram to the appearance of the Korotkoff sound at diastolic pressure), basal metabolic rate, and serum cholesterol concentrations were all within the normal range. Basal and peak TSH after TRH were inversely correlated with serum T4 and FT4I levels. The basal TSH concentration was further inversely correlated with the seasonally altering ambient temperature. These results indicate that during the treatment of primary hypothyroidism with constant doses of T4, 1) serum TSH and its response to TRH show seasonal variation, 2) the hypersecretion TSH in the winter is related to small changes in serum T4 and FT4I levels, and 3) the seasonal variation in the serum TSH concentration may need to be taken into consideration when evaluating the adequacy of a T4 replacement dose. SN - 0021-972X UR - https://www.unboundmedicine.com/medline/citation/6804476/Seasonal_variation_of_serum_thyrotropin_concentration_and_thyrotropin_response_to_thyrotropin_releasing_hormone_in_patients_with_primary_hypothyroidism_on_constant_replacement_dosage_of_thyroxine_ L2 - https://academic.oup.com/jcem/article-lookup/doi/10.1210/jcem-54-6-1118 DB - PRIME DP - Unbound Medicine ER -