Hyperprolactinaemia and its comparision with hypothyroidism in primary infertile women

Correlation of Serum Prolactin and Thyroid Stimulating Hormone Concentration in Infertile Women: A Systematic Review and Meta-Analysis

Infertility affects millions of people of reproductive age worldwide. Thyroid hormones and prolactin (PRL) affect reproduction and pregnancy; therefore, these two hormones influence fertility. This systematic review and meta-analysis aimed to summarise the strength of the correlation between serum PRL and thyroid stimulating hormone (TSH) in infertile women and to explore selected factors influencing the correlation. We conducted a systematic search of online databases (PubMed, Scopus, ScienceDirect, SAGE and Google Scholar) from inception until March 2021 and a manual search of the bibliographies of the included studies to identify relevant publications. The original research paper describing the correlation between PRL and TSH in reproductive-age women with infertility (primary and secondary) was included. The risk of bias was assessed using the Joanna Briggs Institute Critical Appraisal Checklist for Analytical Cross-Sectional Studies. A random effect model was used to estimate the pooled correlations of PRL and TSH, followed by an assessment of heterogeneity and a sensitivity analysis. From a total of 822 relevant articles identified, 11 were eligible and included in this systematic review and meta-analysis. The random effect pooled correlation estimates between PRL and TSH was 0.431 (95% CI: 0.251, 0.582), with substantial heterogeneity between the included studies (I2 = 80%, τ2 = 0.067, P < 0.001). No significant publication bias was observed. Study region, types of infertility, sample size and year of the study did not influence the correlation estimates. Our results highlighted a significant positive moderate correlation between serum PRL and serum TSH in infertile women.

Role of hypothyroidism and associated pathways in pregnancy and infertility: Clinical insights

Thyroid disorders are the most common endocrine problems in women. In most of the cases, thyroid can lead to infertility or miscarriages. The etiology of infertility is multifactorial with thyroid disorders as the most common presenting factor, hypothyroidism in particular. Infertility in women can lead to emotional and psychological stress. The prevalence of hypothyroidism during pregnancy is estimated to be 0.3%–0.5%. Hypothyroidism and hyperthyroidism can result in menstrual irregularities and anovulatory cycles, thus affecting the fertility. There is a significant high prolactin (PRL) level in infertile women with hypothyroidism when compared to euthyroid patients, indicating the relation between hypothyroidism and hyperprolactinemia. The amount of thyrotropin releasing hormone (TRH) from the hypothalamus is markedly increased by inhibition of pyroglutamyl peptidase II, the enzyme catalyzing TRH. The increased TRH in hypothyroidism causes increased thyroid-stimulating hormone and PRL secretion by pituitary, leading to infertility and galactorrhea. In recent years, a neuropeptide called kisspeptin, encoded by Kiss1 gene, a potent stimulus for GnRH secretion, has been recognized, which suggests a future direction of treatment with kisspeptin and benefits the fertility induction among hyperprolactinemic infertile patients. Untreated hypothyroidism during pregnancy can lead to subfertility, fetal deaths, premature deliveries, and abortions. Therefore, women planning for pregnancy and infertile women should be assessed for thyroid hormones and serum PRL.

Estimation of serum prolactin levels and determination of prevalence of hyperprolactinemia in newly diagnosed cases of subclinical hypothyroidism

Background:

Hyperprolactinemia is a common endocrine disorder involving hypothalamic–pituitary axis. Prolactin (PRL) secretion is stimulated by dopamine antagonism and thyroid-releasing hormone. Hyperprolactinemia has been reported in subclinical hypothyroidism (SCH) but results are markedly variable and studies on SCH are very few. The objective of this study was to find out prevalence of hyperprolactinema in newly diagnosed subclinical hypothyroid patients.

Materials and Methods:

In this cross-sectional study, serum PRL levels of 150 newly diagnosed subclinical hypothyroid patients were determined using electrochemiluminescence method.

Results:

Raised PRL levels were found in 18 (%) patients with SCH. There was positive correlation between serum thyroid-stimulating hormone and PRL levels. Prevalence of infertility was significantly higher with presence of hyperprolactinemia than normoprolactinemia in subclinical hypothyroid patients.

Conclusion:

Routine prolactin estimation and subsequent treatment is required in patients with subclinical hypothroidism.

Association of Thyroid Profile and Prolactin Level in Patient with Secondary Amenorrhea

BACKGROUND

Amenorrhea is the absence of menstrual periods. It has multiple social consequences as it may leads to infertility. This case control study was conducted for determining the association of thyroid hormones with hyperprolactinemia in patient with amenorrhea.

METHODS

We investigated 50 women with diagnosed cases of secondary amenorrhoea, who attended UCMS hospital, for hormonal evaluations. Fifty two healthy women were taken as the controls. The thyroid dysfunction and serum prolactin level were reviewed in cases and in the controls.

RESULTS

Mean serum prolactin level was found to be significantly higher in the cases as compared to the controls. Mean serum fT3 and fT4 level in the hyperprolactinemic cases (mean = 2.67, SD = 1.04 pg/ml) and (mean = 1.38, SD = 0.51 ng/dl respectively) were slightly lower as compared to normoprolactinemic cases (mean = 3.21, SD = 1.86 pg/ml) and (mean = 1.73, SD = 1.37 ng/dl) respectively. Mean TSH of normoprolactinemic and hyperprolactinemic cases were comparable (P = 0.049). There was positive correlation between prolactin, BMI and TSH whereas negative correlation of prolactin was seen with fT3, fT4 and age. In hyperprolactainemic cases, prolactin was found to be negatively correlated with TSH (r = -0.155, P = 0.491) whereas prolactin was positively correlated with TSH (r = 0.296, P = 0.126) in normoprolactainemic cases.

CONCLUSIONS

Thus, hyperprolactinemia with thyroid dysfunction may be contributory hormonal factor in patient with amenorrhoea and as such, estimation of prolactin, fT3, fT4 and TSH should be included for diagnostic evaluation of amenorrhea.

Serum macroprolactin levels in pregnancy and association with thyroid autoimmunity

BACGROUND

To assess the contribution of macroprolactin to high serum prolactin levels and their association with thyroid status and thyroid autoimmunity during pregnancy.

METHODS

138 pregnant women who suspected of having thyroid dysfunction were studied and divided into three groups according to the thyroid status; group 1; euthyroidism (n 40), group 2; hypothyroidism (n 54), and group 3; hyperthyroid (n 44). Polyethylene glycol (PEG) precipitation method was used for detection of macroprolactin. A percentage recovery of 40 % or less is considered as macroprolactinemia. If macroprolactin was negative, the percentage of monomeric prolactin recovery (monoPRL %) after PEG precipitation was used for comparison between the groups.

RESULTS

Macroprolactinemia was found in two patients (1.4 %) one from hypothyroid and other from euthyroid group. Basal prolactin levels in these patients were 400 and 403 ng/mL respectively. Referring to all patients, there was no correlation between PRL, macroPRL or monoPRL % with thyroid hormone status and also with the serum levels of thyroid antibodies (p > 0.05). A positive correlation was observed between the serum levels of PRL with TSH (p = 0.014 and r = 0.219), while a negative correlation was found with FT4 (p = 0.011 and r = -0.227).

CONCLUSIONS

Despite the fact that serum prolactin levels were found to be high during pregnancy, the contribution of macroprolactin was found to be insignificant in our study. Unlike other auto immune diseases, we could not find any relationship between thyroid autoimmunity and PRL, macroPRL or monoPRL %. These results confirmed that measured prolactin was quite homogeneous during pregnancy.

Thyroid hormones and prolactin levels in infertile women in southern Nigeria

INTRODUCTION

Human infertility is a complex global health problem. It has multiple social consequences which are especially profound for thyroid hormones in infertility with the aim of determining the degree of association of thyroid hormones with hyperprolactinemia in our population.

MATERIALS AND METHODS

The serum levels of prolactin, T3, T4 and TSH were determined in 90 hyperprolactinemic infertile women, 90 normoprolactinemic infertile women and 50 fertile women. The hormones were assayed using Enzyme Linked Immunosorbent Assay kits.

STATISTICAL ANALYSIS

Analysis of variance and Pearson's correlation were used to analyze the data, with the significant p-level set at 0.05.

RESULTS

A significantly higher mean serum prolactin and TSH were observed among the infertile groups compared to the fertile controls (p<0.05). The mean serum T3 and T4 were significantly lower in the hyperprolactinemic infertile women compared to the fertile controls (p<0.05). The mean TSH and T3 of normoprolactinemic infertile women and controls were comparable (p>0.05). However, the mean T4 was significantly lower in normoprolactinemic infertile women compared to the fertile controls (p<0.05). In all the groups, TSH correlated inversely with T3 and T4, while T3 correlated positively with T4. It was only in the control group that prolactin correlated positively and significantly with TSH.

CONCLUSION

It is therefore concluded that hyperprolactinemia with thyroid dysfunction may be a major contributory hormonal factor in infertility among infertile women and as such, estimation of prolactin, T3, T4 and TSH should be included in the workup for infertile women especially those with hyperprolactinaemia.

Evaluation of serum prolactin level in patients of subclinical and overt hypothyroidism

BACKGROUND

Prolactin secretion is controlled by prolactin inhibitor factor that is secreted from hypothalamus; factors like vasoactive inhibitory peptide (VIP) and thyroid releasing hormone (TRH) lead to increase in prolactin secretion. Hyperprolactinemia is a common condition that can result from a number of causes including hypothyroidism. Objective of the study was to determine correlation between serum levels of prolactin and thyroid hormones in euthyroid, subclinical and overt hypothyroid cases.

MATERIALS AND METHODS

Consecutive patients presenting for various thyroid related problems were segregated into two groups subclinical and overt hypothyroidism according to their diagnosis based on history and clinical examination, laboratory reports, inclusion and exclusion criteria. Newly diagnosed 75 patients in each group were finally enrolled. Similar number of age and sex matched controls were selected. All subjects filled a predesigned questionnaire for the evaluation of hypothyroid symptoms. Thyroid profile for T3, T4 (total and free), TSH and prolactin were determined in all the subjects and analyzed.

RESULTS

Prolactin elevation was found in 16 patients (21.33 %) with overt hypothyroidism, and in six patients (8%) with subclinical hypothyroidism. The control group and subclinical hypothyroid patients exhibited no significant difference in terms of total and free T3, total and free T4. For TSH and prolactin on the other hand, a statistically significant elevation was found in patients with overt hypothyroidism when compared with subclinical hypothyroidism; and in patients with subclinical hypothyroidism when compared to the controls. A significant statistical difference was observed between the two groups of hypothyroid patients for all hypothyroid symptoms except alopecia and hirsuitism.

CONCLUSION

The incidence of hyperprolactinemia in hypothyroidism was found to be higher when compared with normal controls. Serum prolactin assessment should be performed on all patients with hypothyroidism (overt and subclinical) before performing further tests.