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ORIGINAL ARTICLE
Year : 2019  |  Volume : 12  |  Issue : 3  |  Page : 217-224  

A study on thyroid profile and prolactin level in hypothyroid females of a rural population of a developing country


1 Department of Physiology, Burdwan Medical College and Hospital, Burdwan, West Bengal, India
2 Department of Physiology, Rampurhat Government Medical College and Hospital, Rampurhat, West Bengal, India

Date of Submission31-Jul-2018
Date of Acceptance16-Jan-2019
Date of Web Publication15-May-2019

Correspondence Address:
Arunima Chaudhuri
Krishnasayar South, Borehat, Burdwan - 713 102, West Bengal
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/mjdrdypu.mjdrdypu_121_18

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  Abstract 


Background: In patients with primary hypothyroidism, there are increased levels of thyrotropin-releasing hormone (TRH) which can cause rise of prolactin (PRL) levels and these patients may have galactorrhea. Aims: Considering the clinical importance of hyperprolactinemia in ovulation disorders, sterility, and menstruation disorders, the present study was conducted to observe the prevalence of hyperprolactinemia and related galactorrhea in newly diagnosed hypothyroid females and correlate serum PRL level with thyroid-stimulating hormone (TSH) in hypothyroid females in a rural population of East India. Materials and Methods: This pilot study was conducted in Burdwan Medical College on 200 newly diagnosed female hypothyroid participants after taking institutional ethical clearance and informed consent of the participants. Age and gender-matched 100 controls were taken. Serum TSH, serum free thyroxine (fT4), and serum PRL levels were assessed. A questionnaire was designed for the evaluation of hypothyroidism symptoms for all the participants. These symptoms were galactorrhea, dryness of skin, feeling cold, hair loss, weakness, weight gain, constipation, loss of libido, and menstrual abnormalities. A total number of hyperprolactinemic patients were 42; out of them, 30 females were clinical and 12 were subclinical hypothyroid patients. One hundred and fifty-eight patients had normal PRL level. Results: Significant difference was found between clinical and subclinical hypothyroid females for body mass index (BMI) (P = 0.002), TSH (P < 0.0001), fT4 (P < 0.0001), and PRL (P = 0.002). The prevalence of hyperprolactinemia was 21% in hypothyroid females, 23.07% in clinical or overt hypothyroid females, and 17.14% in subclinical hypothyroid females. The prevalence of galactorrhea is 1% in all hypothyroid females and 1.53% in clinical hypothyroid females. A significant positive correlation was found between TSH and PRL in hypothyroid patients. Conclusions: Incidence of hyperprolactinemia is found to be notable in hypothyroid females including clinical and subclinical hypothyroidism, and hypothyroid females show positive correlation between TSH and PRL levels. Hence, PRL levels need to be assessed in all hypothyroid females.

Keywords: Galactorrhea, hyperprolactinemia, hypothyroidism


How to cite this article:
Koner S, Chaudhuri A, Biswas A, Adhya D, Ray R. A study on thyroid profile and prolactin level in hypothyroid females of a rural population of a developing country. Med J DY Patil Vidyapeeth 2019;12:217-24

How to cite this URL:
Koner S, Chaudhuri A, Biswas A, Adhya D, Ray R. A study on thyroid profile and prolactin level in hypothyroid females of a rural population of a developing country. Med J DY Patil Vidyapeeth [serial online] 2019 [cited 2019 Dec 15];12:217-24. Available from: http://www.mjdrdypv.org/text.asp?2019/12/3/217/258196




  Introduction Top


Hypothyroidism is a common health problem in India and worldwide. It has a wide clinical spectrum ranging from myxedema, end-organ damage, and multisystem failure to a subclinical condition. In patients with primary hypothyroidism, there are increased levels of thyroid-realizing hormone (TRH) which can cause rise of prolactin (PRL) levels and these patients may have galactorrhea.[1],[2],[3],[4],[5],[6] TRH causes stimulation of PRL secretion by activating thyrotropin-releasing hormone receptors directly in lactotrophs or by regulating dopamine secretion from hypothalamus indirectly.[2] Decreased PRL clearance from systemic circulation, reduced sensitivity to suppressant effect of dopamine on PRL synthesis, and elevated PRL messenger RNA also contribute to increased PRL level in hypothyroidism.[6]

PRL secretion is controlled by PRL inhibitory factor which is secreted from hypothalamus; other factors such as vasoactive inhibitory peptide and TRH may also lead to increase in PRL secretion. Increased level of serum PRL has been reported in 30% of patients with primary hypothyroidism in previous studies.[1],[2],[3],[4],[5],[6],[7],[8],[9]

In a study by Bahar et al. in 2011[7] in Sari, Iran, PRL levels of 481 subclinical hypothyroid patients were assessed. PRL measurement was performed using chemiluminescent immunoassay. The prevalence of hyperprolactinemia in subclinical hypothyroidism was 20.4% (11% in men and 22% in women, P = 0.05). There was no correlation between the serum thyroid-stimulating hormone (TSH) and PRL level. This study showed that the prevalence of hyperprolactinemia in subclinical hypothyroidism is notable and this disorder is more common in female subclinical hypothyroidism than the men.

Goswami et al. in 2009[8] investigated 160 women with primary infertility who attended the Biochemistry Department, Maulana Azad Medical College, New Delhi, for hormonal evaluations. Eighty fertile women with similar age and socioeconomic status were enrolled as the controls. The association between thyroid dysfunction and levels of serum PRL, luteinizing hormone, and follicle-stimulating hormone as their menstrual status was reviewed. The infertile women with hypothyroidism had significantly higher PRL levels when compared to the participants with hyper- or euthyroidism. There was a significant association between abnormal menstrual patterns and anovulatory cycles, as observed on endometrial examination of infertile patients. There was a greater propensity for thyroid disorder in infertile women than the fertile ones and also a higher prevalence of hyperprolactinemia in infertile patients.

In a study conducted by Goel et al. in 2015[9] in Meerut, India, consecutive patients presenting for various thyroid-related problems were segregated into two groups subclinical and overt hypothyroidism. Newly diagnosed 75 patients in each group were finally enrolled. A similar number of age- and sex-matched controls were selected. All participants filled a predesigned questionnaire for the evaluation of hypothyroid symptoms. Thyroid profile for T3, T4 (total and free), TSH, and PRL were determined in all the participants and analyzed. PRL 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 and total and free T4. For TSH and PRL 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.

Considering the clinical importance of hyperprolactinemia in ovulation disorders, sterility, and menstruation disorders,[8] the present study was conducted to observe the prevalence of hyperprolactinemia and related galactorrhea in newly diagnosed hypothyroid females and correlate serum PRL level with TSH in hypothyroid females in a rural population of East India.


  Materials and Methods Top


This pilot study was conducted in Burdwan Medical College on 200 newly diagnosed female hypothyroid participants in a period of 12 months commencing from April 2016 and continuing till May 2017 after taking institutional ethical clearance and informed consent of the participants (Memo No. BMC/PG/4423, dated: 14/12/2015). The formula used to calculate the size of the required sample was n = (z)2 p (1 − p)/d2, where, n = sample size, z = z statistic for a level of confidence (95% level of confidence used, therefore, z = 1.96), P = expected prevalence of proportion, and d = desired precision (taken as 6%), and previous studies were taken into consideration.[6],[7]

Inclusion criteria

Newly diagnosed hypothyroid females in the age group of 20–50 years attending in the Department of Biochemistry, Burdwan Medical College, were included in the study.

Exclusion criteria

  1. Pregnancy
  2. Lactation
  3. Liver diseases (liver function tests were done)
  4. Renal diseases (serum creatinine was estimated)
  5. Any history suggestive of visual field defect/headache/seizure
  6. Participants on drugs causing increased PRL.


Detailed history was taken from each participant as per case record format. The participants were clinically evaluated followed by general survey and systemic examination. Body mass index (BMI) was calculated. Serum TSH, serum free thyroxine (fT4), and serum PRL tests were done in biochemistry laboratory for every participant for confirmation. A questionnaire was designed for the evaluation of hypothyroidism symptoms for all the participants. These symptoms were galactorrhea, dryness of skin, feeling cold, hair loss, weakness, constipation, loss of libido, and menstrual abnormalities.

Hypothyroidism was defined as clinical as an elevated TSH (>6.16 μIU/ml) with a decreased serum fT4 level (<0.8 ng/dl) and subclinical as an elevated TSH (>6.16 μIU/ml) together with normal fT4 levels (0.8–2.0 ng/dl). Hyperprolactinemia was defined as elevated serum PRL (>19.5 ng/ml).

One hundred controls were included in the study (mean age: 30.82 ± 6.55 years, mean BMI: 20.94 ± 0.95 kg/m2, mean TSH: 1.90 ± 0.91 μIU/ml, mean fT4: 1.32 ± 0.24 ng/dl, and mean PRL: 11.59 ± 2.56 ng/ml). None of these participants had hypothyroidism and hyperprolactinemia.

BMI ≥23 was considered as overweight and taken as weight gain for the study.

Estimation of serum TSH level was done by quantitative determination of TSH concentration by microplate immunoenzymometric assay using Monobind Inc., USA, manufactured TSH AccuBind ELISA Kit.

Estimation of serum fT4 level was done by quantitative determination of fT4 concentration by microplate enzyme immunoassay (EIA) using Monobind Inc., USA, manufactured Free T4 AccuBind ELISA Kit.

Estimation of serum PRL level was done by quantitative determination of PRL concentration by microplate immunoenzymometric assay using Monobind Inc., USA, manufactured PRL AccuBind ELISA Kit.

Biochemical methods

Estimation of thyroid-stimulating hormone

Measurement of serum TSH is generally regarded as the most sensitive indicator for the diagnosis of hypothyroidism.

Test principle (method – immunoenzymometric assay)

The immobilization occurs at the surface of microplate well between the interaction of streptavidin coated on the well and biotinylated monoclonal anti-TSH antibody. By mixing the monoclonal biotinylated antibody, the enzyme-labeled antibody, and a serum-containing native antigen, reaction occurs between native antigen and the antibodies to form a soluble sandwich complex. Then, the complex is deposited to the well. After equilibrium is achieved, the antibody-bound fraction is separated from unbound antigen by aspiration or decantation. The enzymatic activity of the antibody-bound fraction which is directly proportional to the native-free antigen concentration is measured by adding substrate. By utilizing calibrators of known antigen concentrations, a dose–response curve can be generated from which the antigen concentration of an unknown sample can be ascertained.

Kit content

  1. Streptavidin-coated microplates: 96 wells coated with streptavidin and packaged in an aluminum bag with a drying agent
  2. TSH enzyme reagent: 13 ml/vial containing enzyme-labeled polyclonal antibody, biotinylated monoclonal IgG in buffer, dye, and preservative
  3. Thyrotropin calibrators: Seven vials (0.5 ml/vial) of references for TSH antigen at levels of 0, 0.5, 2.5, 5.0, 10, 20, and 40 μIU/ml
  4. Substrate A (7 ml/vial): one bottle containing tetramethylbenzidine (TMB) in buffer
  5. Substrate B (7 ml/vial): one bottle containing hydrogen peroxide (H2O2) in buffer
  6. Stop solution (8 ml/vial): one bottle containing a strong acid (1 N HCL)
  7. Wash solution concentrate (20 ml): one vial containing a surfactant in buffered saline. A preservative has been added.


Quality control

Each laboratory should assay controls at levels in the low, normal, and elevated range for monitoring assay performance. These controls should be treated as unknowns and values determined in every test procedure performed. Quality control charts should be maintained to follow the performance of the supplied reagents. Pertinent statistical methods should be employed to ascertain trends. The individual laboratory should set acceptable assay performance limits. Other parameters that should be monitored include the 80%, 50%, and 20% intercepts of the dose–response curve for run-to-run reproducibility. In addition, maximum absorbance should be consistent with past experience. Significant deviation from established performance can indicate unnoticed change in experimental conditions or degradation of kit reagents. Fresh reagents should be used to determine the reason for the variations.

Calculation of results

  1. Calculation of the mean absorbance value of calibrator and samples was done at 450 nm
  2. A point-to-point curve was plotted by plotting the absorbance of each calibrator on the vertical Y-axis against concentration of each calibrator on the horizontal or X-axis
  3. Using the absorbance value for each sample, the corresponding concentration of TSH was determined in μIU/ml from the standard curve.


Estimation of free thyroxine

Thyroxine circulates in blood almost bound to carrier proteins. Thyroxine-binding globulin is the main carrier protein. Only the free (unbound) fraction of thyroxine is biologically active. Concentrations of the carrier proteins are altered in different clinical conditions. Hence, the fT4 concentration remains constant. The measurement of fT4 concentration correlates better than total thyroxine level.

Test principle (competitive enzyme immunoassay)

In competitive EIA, a competitive reaction results between the native-free antigen and enzyme–antigen conjugate for limited number of insolubilized binding sites on antibody coated on the microwell. After the equilibrium is attained, the antibody-bound fraction is separated from unbound antigen by aspiration or decantation. The enzymatic activity of the antibody-bound fraction which is inversely proportional to the native-free antigen concentration is measured by adding substrate. By utilizing calibrators of known antigen concentrations, a dose–response curve can be generated from which the antigen concentration of an unknown sample can be found out.

Kit contents

  1. fT4 antibody-coated microplate (96 wells): one 96-well microplate coated with anti-thyroxine serum
  2. Enzyme reagent (13 ml/vial): one vial of thyroxine–horseradish peroxidase conjugate in a protein-stabilized matrix
  3. fT4 calibrators (0.5 ml/vial): six vials of human serum-based reference calibrators for fT4
  4. Substrate A (7 ml/vial): one bottle containing TMB in acetate buffer
  5. Substrate B (7 ml/vial): one bottle containing H2O2 in acetate buffer
  6. Wash solution concentrate (20 ml): one vial containing a surfactant in buffered saline
  7. Stop solution (8 ml/vial): one bottle containing a strong acid (1 N HCL).


Quality control

Each laboratory should assay controls at levels in the hypothyroid, euthyroid, and hyperthyroid range for monitoring assay performance. These controls should be treated as unknowns and values determined in every test procedure performed. Quality control charts should be maintained to follow the performance of the supplied reagents. Pertinent statistical methods should be employed to ascertain trends. Significant deviation from established performance can indicate unnoticed change in experimental conditions or degradation of kit reagents. Fresh reagents should be used to determine the reason for the variations.

Calculation

  1. Calculation of absorbance value was done at 450 nm
  2. A point-to-point curve was plotted by plotting the absorbance of each calibrator on Y-axis against concentration of each calibrator on X-axis
  3. Using the absorbance value for each sample, the corresponding concentration of fT4 was determined in ng/dl from the standard curve.


Estimation of serum prolactin

Test principle (immunoenzymometric assay)

The immobilization takes place at the surface of microplate well between the interaction of streptavidin coated on the well and biotinylated monoclonal anti-PRL antibody. By mixing the monoclonal biotinylated antibody, the enzyme-labeled antibody, and a serum-containing native antigen, reaction occurs between native antigen and the antibodies to form a soluble sandwich complex. Then, the complex is deposited to the well. After attaining the equilibrium, the antibody-bound fraction is separated from unbound antigen by aspiration or decantation. The enzymatic activity of the antibody-bound fraction which is directly proportional to the native-free antigen concentration is measured by adding substrate. By utilizing calibrators of known antigen concentrations, a dose–response curve can be generated from which the antigen concentration of an unknown sample can ascertain.

Kit content

  1. Streptavidin-coated microplates (96 wells)
  2. PRL enzyme reagent (13 ml/vial): one vial containing enzyme-labeled antibody and biotinylated monoclonal antibody
  3. PRL calibrators (1 ml/vial): six vials of references for PRL antigen in human serum
  4. Substrate A (7 ml/vial): one bottle containing TMB in buffer
  5. Substrate B (7 ml/vial): one bottle containing H2O2 in buffer
  6. Wash solution concentrate (20 ml): one vial containing a surfactant in buffer saline
  7. Stop solution (8 ml/vial): one bottle containing a strong acid (1N HCL).


Quality control

Each laboratory should assay controls at levels in the low, normal, and elevated range for monitoring assay performance. These controls should be treated as unknowns and values determined in every test procedure performed. Quality control charts should be maintained to follow the performance of the supplied reagents. Pertinent statistical methods should be employed to ascertain trends. Significant deviation from established performance can indicate unnoticed change in experimental conditions or degradation of kit reagents. Fresh reagents should be used to determine the reason for the variations.

Calculation

A dose–response curve is used to ascertain the concentration of PRL hormone.

  1. Calculation of absorbance value was done at 450 nm
  2. A point-to-point curve was plotted by plotting the absorbance of each calibrator on Y-axis against concentration of each calibrator on X-axis on linear graph paper
  3. Using the absorbance value for each sample, the corresponding concentration of PRL was determined in ng/ml from the standard curve.


The computer software Statistical Package for the Social Sciences (SPSS) version 16 (SPSS Inc. Released 2007. SPSS for Windows, Version 16.0. Chicago, SPSS Inc.) was used to analyze the data. The difference between the groups was considered significant and highly significant if the analyzed probability values (P value) were P < 0.05* and P < 0.01**, respectively.


  Results Top


Two hundred newly diagnosed hypothyroid females were enrolled in our study. Among these, 130 were clinical hypothyroid and 70 were subclinical hypothyroid patients. A total number of hyperprolactinemic patients were 42; out of them, 30 females were clinical and 12 were subclinical hypothyroid patients. One hundred and fifty-eight patients had normal PRL level.

One hundred controls were included in the study (mean age: 30.82 ± 6.55 years, mean BMI: 20.94 ± 0.95 kg/m2, mean TSH: 1.90 ± 0.91 μIU/ml, mean fT4: 1.32 ± 0.24 ng/dl, and mean PRL: 11.59 ± 2.56 ng/ml). None of these participants had hypothyroidism and hyperprolactinemia.

Significant difference was found between clinical and subclinical hypothyroid females for mean BMI (31.89 ± 6.79 kg/m2 vs. 31.25 ± 6.60 kg/m2, P = 0.002), mean TSH (23.84 ± 8.21 μIU/ml vs. 9.83 ± 2.21 μIU/ml, P < 0.0001), mean fT4 (0.61 ± 0.08 ng/dl vs. 0.61 ± 0.08 ng/dl, P < 0.0001), and mean PRL (20.51 ± 18.26 ng/ml vs. 15.15 ± 6.16 ng/ml, P = 0.002) [Table 1] and [Figure 1], [Figure 2], [Figure 3].
Table 1: Age, body mass index, thyroid-stimulating hormone values, free thyroxine values, and prolactin values of clinical and subclinical hypothyroid participants

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Figure 1: Thyroid-stimulating hormone values of clinical and subclinical hypothyroidism

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Figure 2: The free thyroxine of clinical and subclinical hypothyroidism

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Figure 3: The prolactin values of clinical and subclinical hypothyroidism

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[Table 1] shows that the difference of BMI, TSH values, ft4 values, and PRL values between clinical and subclinical hypothyroidism was highly significant.

The prevalence of hyperprolactinemia was 21% in all hypothyroid females, 23.07% in clinical or overt hypothyroid females, and 17.14% in subclinical hypothyroid females. The prevalence of galactorrhea is 1% in all hypothyroid females and 1.53% in clinical hypothyroid females. No galactorrhea was found in subclinical hypothyroid patients. About 4.76% galactorrhea was observed in hypothyroid females with increased PRL and 6.66% galactorrhea was observed in clinical hypothyroid females with increased PRL.

A significant positive correlation was found between TSH and PRL (r = 0.399, P < 0.001) in all hypothyroid patients (total number = 200) [Table 2] and [Figure 4].
Table 2: Correlation between thyroid-stimulating hormone and serum prolactin level in all hypothyroid patients

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Figure 4: A positive correlation was found between thyroid-stimulating hormone and prolactin levels (r = 0.399, P < 0.001)

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A significant positive correlation was found between TSH and PRL (r = 0.0.406, P < 0.001) in clinical hypothyroid patients (total number = 130) and between TSH and PRL (r = 0.345, P = 0.003) in subclinical hypothyroid patients (total number = 70). A significant positive correlation was found between TSH and PRL (r = 0.805, P < 0.00001) in hyperprolactinemic patients (total number = 42), whereas no significant correlation was found (r = 0.063, P = 0.431) in normoprolactinemic patients (total number = 158).

The difference in PRL level between clinical and subclinical hypothyroidism was highly significant [Table 3].
Table 3: Comparison of prolactin level between clinical and subclinical hypothyroidism

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[Table 3] demonstrates that difference in PRL level between clinical and subclinical hypothyroidism was highly significant.

Significant difference was observed for galactorrhea (0% vs. 4.76%, P = 0.005), weakness (31.64% vs. 47.61%, P = 0.02), and menstrual abnormalities (19.62% vs. 42.85%, P = 0.001) as clinical features between normal and increased PRL levels in all hypothyroid patients [Table 4].
Table 4: The comparison of clinical features of all hypothyroid patients with normal prolactin and increased prolactin

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[Table 4] shows comparison of the clinical features of all hypothyroidism with normal and increased PRL values. The difference of percentage of galactorrhea and menstrual abnormalities was highly significant and the difference in percentage of weakness was significant between normal and increased PRL levels. The difference in other clinical features was not significant.

In clinical hypothyroidism, a significant difference was observed for galactorrhea (0% vs. 6.66%, P = 0.009), weakness (36% vs. 60%, P = 0.01), and menstrual abnormalities (25% vs. 46.66%, P = 0.02) between normal and increased PRL levels. In subclinical hypothyroidism, a significant difference was observed for dryness of skin (37.93% vs. 8.33%, P = 0.04) and menstrual abnormalities (10.34% vs. 33.33%, P = 0.03) between normal and increased PRL levels.

The difference of percentage of feeling cold and weight gain was highly significant and percentage of hair loss, weakness, and menstrual abnormalities was significantly different between clinical and subclinical hypothyroid patients [Table 5].
Table 5: Comparison of clinical features between clinical and subclinical hypothyroidism

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[Table 5] shows comparison of the clinical features of clinical and subclinical hypothyroidism. The difference of percentage of feeling cold and weight gain was highly significant and percentage of hair loss, weakness, and menstrual abnormalities was significantly different between clinical and subclinical hypothyroid patients.


  Discussion Top


According to various studies, 42 million of people suffer from thyroid disorders in India.[10],[11] Hypothyroidism is more common in female.[7] Hyperprolactinemia is the most common endocrine problem of hypothalamic–pituitary axis[12] and occurs mostly in women.[10],[11] Hyperprolactinemia occurs by increased production of PRL and often leads to galactorrhea and reproductive dysfunction and hyperprolactinemia can be developed in primary hypothyroidism by a variety of mechanisms.[1],[2],[3],[4],[5],[6]

The present study was conducted to observe the prevalence of hyperprolactinemia and related galactorrhea in newly diagnosed hypothyroid females and correlate serum PRL level with TSH in hypothyroid females in a rural population of East India. Two hundred newly diagnosed hypothyroid females were examined in the present study and 100 females with no evidence of hypothyroidism were selected as control. Among these, 130 were clinical hypothyroid and 70 were subclinical hypothyroid patients. A total number of hyperprolactinemia patients were 42 out of 200. Thirty were clinical and 12 were subclinical hypothyroid participants among 42 hyperprolactinemic participants. One hundred and fifty-eight were with normal PRL level.

We found a significant difference between clinical and subclinical hypothyroid participants for BMI (P = 0.002), TSH (P < 0.0001), fT4 (P < 0.0001), and PRL value (P = 0.002). About 65% clinical hypothyroid and 35% subclinical hypothyroid patients, 21% with increased PRL and 79% with normal PRL patients, and 65% with decreased fT4 and 35% with normal fT4 patients are observed among all study participants.

Goel et al.[9] in their study observed that PRL was increased in 21.33% subjects with overt hypothyroidism and 8% in subjects with subclinical hypothyroidism. Bahar et al.[7] in their study observed that the prevalence of hyperprolactinemia was 22% in women with subclinical hypothyroidism (91 females had high PRL levels among 419 females). Hekimsoy et al.[6] observed PRL elevation in 36% with overt hypothyroidism and 22% with subclinical hypothyroidism. In our study, we observed that the prevalence of hyperprolactinemia is 21% in all hypothyroid females, 23.07% in clinical or overt hypothyroid females, and 17.14% in subclinical hypothyroid females, respectively.

Bahar et al.[7] in their study reported 2.6% galactorrhea in subclinical hypothyroid patients. In the present study, we found that the prevalence of galactorrhea is 1% in all hypothyroid females and 1.53% in clinical hypothyroid females. No galactorrhea is found in subclinical hypothyroidism.

We observed a significant positive correlation between TSH and PRL (r = 0.399, P < 0.001) in all hypothyroid patients, between TSH and PRL (r = 0.406, P < 0.001) in clinical hypothyroid patients, and between TSH and PRL (r = 0.345, P = 0.003) in subclinical hypothyroid patients. Hekimsoy et al.[6] in their study on hypothyroid patients (overt and subclinical) found a positive correlation between TSH and PRL levels. In a study by Alsultance,[13] a positive correlation was found between hypothyroidism and hyperprolactinemia. Kumkum et al.[14] and Lal et al.[15] observed a positive correlation between TSH and PRL in infertile women.

We found that the difference of occurrence of galactorrhea (4.76% with increased PRL and 0% with normal PRL, P = 0.005), weakness (47.61% with increased PRL and 31.64% with normal PRL, P = 0.02), and menstrual disorders (42.85% with increased PRL and 19.62% with normal PRL, P = 0.001) was statistically significant between normal and increased PRL levels in all hypothyroid females whereas the difference of other clinical features such as dryness of skin (P = 0.43), feeling cold (P = 0.54), hair loss (P = 0.51), weight gain (P = 0.58), constipation (P = 0.40), and loss of libido (P = 0.61) was not statistically significant.

In our study, we also observed that the difference of occurrence of galactorrhea (6.66% with increased PRL and 0% with normal PRL, P = 0.009), weakness (60% with increased PRL and 36% with normal PRL, P = 0.01), and menstrual abnormalities (46.66% with increased PRL and 25% with normal PRL, P = 0.02) was statistically significant between normal and increased PRL levels in clinical hypothyroid females. The difference of occurrence of dryness of skin (8.33% with increased PRL and 37.93% with normal PRL, P = 0.04) and menstrual abnormalities (33.33% with increased PRL and 10.34% with normal PRL, P = 0.03) was statistically significant between normal and increased PRL levels in subclinical hypothyroid females. We found a significant difference between clinical and subclinical hypothyroid participants for feeling cold (P = 0.0006), weakness (P = 0.01), weight gain (P = 0.002), menstrual abnormalities (P = 0.01), and hair loss (P = 0.03).

Goel et al.[9] observed a significant statistical difference between overt and subclinical hypothyroid patients for all hypothyroid symptoms (fatigue, dryness of skin, cold intolerance, constipation, and weight gain) except alopecia and hirsutism.

We had included 100 participants as controls in this study, and all these participants had normal levels of TSH, fT4, and PLR levels. Hence, with negative control group, we conclude that the observed interrelationship is not by chance and might be related to the thyroid problem.


  Conclusions Top


Hyperprolactinemia causes reproductive disorders in females. The incidence of hyperprolactinemia is found to be notable in hypothyroid females including clinical and subclinical hypothyroidism, and hypothyroid females show positive correlation between TSH and PRL levels. Hence, PRL levels need to be assessed in all hypothyroid females.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
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Goswami B, Patel S, Chatterjee M, Koner BC, Saxena A. Correlation of prolactin and thyroid hormone concentration with menstrual patterns in infertile women. J Reprod Infertil 2009;10:207-212.  Back to cited text no. 8
    
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Goel P, Kahkasha, Narang S, Gupta BK, Goel K. Evaluation of serum prolactin level in patients of subclinical and overt hypothyroidism. J Clin Diagn Res 2015;9:BC15-7.  Back to cited text no. 9
    
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    Figures

  [Figure 1], [Figure 2], [Figure 3], [Figure 4]
 
 
    Tables

  [Table 1], [Table 2], [Table 3], [Table 4], [Table 5]



 

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