Serum thyroglobulin during the menstrual cycle, during pregnancy, and post partum

Abstract

Serum thyroglobulin, TSH, thyroid hormones and thyroid volume were investigated during the menstrual cycle in 10 healthy females (day 2, 9, 16, 23 and day 2 of next cycle), during pregnancy (week 18, 24, 30 and 36) and post partum (1, 2, 3, 6 and 12 months) in 20 healthy females. During the menstrual cycle median serum thyroglobulin increased from 27 (day 2) to 32 \ g=m\ g/ l (day 23, p < 0.01 ). Serum TSH and thyroid volume demonstrated a similar increase with a positive correlation between serum thyroglobulin and thyroid volume (r = 0.65, p < 0.02).Median serum thyroglobulin was significantly increased during the whole pregnancy (week 36, 73 \g=m\g/l )compared with post partum (1 month post partum, 22 \g=m\g/l ,p <0. 01) , as was thyroid volume. Serum TSH was unaltered and free thyroid hormone indices decreased during pregnancy compared with post partum. No relation between changes in serum thyroglobulin and thyroid volume, TSH or thyroid hormones could be demonstrated. Serum thyroglobulin alterations thus were related to alterations in TSH and thyroid volume during the menstrual cycle. However, the increase in serum thyroglobulin and thyroid volume during pregnancy were unrelated to changes in serum TSH, indicating other mechanisms of regulation than TSH. When interpreting serum thyroglobulin levels in women, the co-existence of pregnancy and time of menstrual cycle should be taken into account in order to avoid misinterpretation of results.The menstrual cycle is associaled with marked al¬ terations in Ihyroid size bul nol thyroid function (1). Pregnancy and the postparlum period involve substantial variations in thyroid function as well as thyroid size (2) although il is generally agreed lhat healthy women are euthyroid during this period. No sludies of serum Ihyroglobulin (Tg) during ihe menslrual cycle are available and pregnancy-re¬ lated alterations of serum Tg have been controver¬ sial (3-8). In view of ihe increasing use of serum Tg in differenl thyroid disorders and in the follow-up of patients with differentiated thyroid carcinoma we have found it of inleresl to investigate the in¬ fluence of ihese physiologic factors on serum Tg in heallhy women. Our aim was lo investigate the in¬ terrelationship between serum Tg, serum thyrotropin and Ihyroid size during ihe menstrual cycle, during pregnancy and post partum. Part of the re¬ sults relating to thyroid size and function have pre¬ viously been published (1,2). These results will be mentioned only when important for the study of their relation to serum Tg. Subjects and Methods SubjectsIncluded in the study were the following subjects:1. Ten healthy women with a median age of 26 years (range 18 to 42) and a median body weight, on day 2 of their menstrual cycle, of 54 kg (range 52 to 64).

Trimester-Specific Changes in Maternal Thyroid Hormone, Thyrotropin, and Thyroglobulin Concentrations During Gestation: Trends and Associations Across Trimesters in Iodine Sufficiency

“…We also detected no increase in Tg until the third trimester. Increased Tg has been shown by others in relatively iodine deficient women (22,23).…”

Iodine status, thyroid function and pregnancy: study of Swedish and Sudanese women

“…In a series of illustrative investigations in Belgium (Glinoer et al, 1990;Glinoer et al, 1995), it was shown that the FT4 levels tend to decrease and the TSH levels to increase, but remain within the reference ranges of non-pregnant individuals. Several reports indicate an increase in thyroid volume during pregnancy (Glinoer et al, 1990;Rasmussen et al, 1989;Glinoer et al, 1995). Precise determinations of thyroid volume need thyroid ultrasonography.…”

Effects of menstrual cycle showing infradian rhythm on thyroid blood flow and thyroid volume in healthy women

“…Few studies in the literature reported different results. While some studies showed that TV reached peak at luteal phase during MC (Rasmussen et al 1989;Chan et al 1998), a correlation was also shown between TSH and Tg, and TV (Rasmussen et al 1989). In pregnancy, increases in Tg and TV were demonstrated without any alterations in levels of TSH or thyroid hormones.…”

“…Therefore, it could theoretically be expected that physiological changes in LH and FSH within MC would also occur in TSH, and intra-cycle changes in TSH would lead to alterations in TV and thyroid blood flow. In literature, there are few studies evaluating TV, thyroid functions, and Tg levels during MC (Hegedu¨s et al 1986;Rasmussen et al 1989). Thyroid Doppler parameters were also studied throughout MC (Chan et al 1998(Chan et al , 1999Krezia et al 2004).…”