Reference Range of Prolactin level in Sudanese non Pregnant Women Living in Khartoum State (Pilot Study)

Introduction

Prolactin (PRL) is a peptide hormone secreted by the lactotrophs in the anterior pituitary gland [1]. When secreted in excess, it increases adrenal androgens and blunts the response of gonadotropes and gonadal cells to tropic factors by decreasing the gonadoliberin. As consequently chronically elevated prolactin induce amenorrhea and infertility in women and impotence in men [2-4]. During pregnancy and lactation circulating levels of prolactin increased about ten folds and that is due to hormonal changes during pregnancy, primary the change in estrogen levels [5,6]. Measurement of prolactin concentration in the blood is essential in evaluating patients with infertility or suspected hypothalamic-pituitary dysfunction. The infertility clinic in Sudan uses the international standard level of prolactin as reference point.

Hyperprolactinemia is the most common pituitary hormonal abnormality. Prolactinomas are the prolactin secreting tumours of the pituitary gland is secreting pituitary tumors, it’s the most common cause of tumoral hyperprolactinemia high levels of prolactin result in unovulation, secondary to inhibition of luteinizing hormone pulsatility [7]. It has been suggested that raised prolactin levels can also compromise follicular development and reduce corpus luteal sensitivity to luteinizing hormone with a resulting reduction in progesterone secretion. However, ovarian sensitivity to prolactin is very variable and moderately elevated levels may have no effect in some cases but cause anovulation and amenorrhea in others [8]. Increased PRL level is considered as a risk factor for human breast and probably prostate cancer but more data is needed to prove this [9].

Serotonergic receptor mediates prolactin release and that is why chronic use of serotonin reuptake inhibitors such as Fluoxetine leads to increase prolactin level [10]. The chronic use of Haloperidol (Dopamine antagonist) is associated with high prolactin [11]. Prolactin is secreted in pulstile fashion with 4-14 pulses per day (60% occur during the sleep), the secretary pulses begin 60-90 min after onset of sleep so the blood test recommended being taken two hours after waken up [12,13]. Prolactin in the postpartum women was found in high concentration (140 ng/ml) during first three days followed by a rapid fall to be around 30 ng/ml by day eleven [12]. Breast pump, suckling and stimulation of the nipple and areola can increase the prolactin level [14].

In a study on three ethnic groups of India; Rajput’s, Gorkhas and South-Indians in May 2010 for evaluation of the plasma hormones including prolactin by using Enzyme-Immunoassay (EIA), the results indicated that plasma hormone concentrations were within physiological range and inter-ethnic differences were most prominent between north-(Rajput’s and Gorkhas) and south-Indians [15].

In another study done in 1990 by Key, on Sex hormones in women in rural China and in Britain, prolactin concentrations did not differ significantly between the two countries in any age group [16]. In 2007 study done on serum level of prolactin in normally menstruating Nigerian women aged 17-40 years by Amballi AA, Dada OA, Adeleye AO and Jide Salu using ELA prolactin level was 157.0-302.2 iu/L [17].

Methodology

Across sectional descriptive study was conducted in Khartoum state on 20 non-pregnant Sudanese women aged from 18-35 years old. Ethical approval taken from the National Ribat University and all the subjects signed a written consent for this study.

2.5 ml of venous blood was collected from each subject; collections were done between 10-11:00am during menstruation. The blood was collected into lithium heparin container. Each sample was centrifuged at 50.000 rounds per mints for 5 min. The serum obtained was put into a plant container and stored at -30C0. Samples were analyzed by using PRL Immuo Enzymometric Assay by TOSOH AIA system Analyzer. The various assays results were analyzed by using the SPSS (Statistical Package for the Social Science) version 25.

Results

In this study the minimum level of prolactin was 92.10 IU/L and the maximum value was 241 iu/l while the mean was 188.61. About 10% of subjects (2 subjects) their prolactin was 169 IU/L and another 10% was 197 IU/l. There was a correlation between menarche (first menstrual cycle) and prolactin level but not that significance as shown in Table 1.

Table 1: Mean Prolactin IU/L in Related to First Period Age

*it is an odd result, significant negative correlation between age and prolactin, prolactin diminished with age.

Discussion

In Amballi (17) study which was done in 2007 the prolactin range was between 157-302; while in this study the range was found to be from 92.10 up to 241miu/l which is significantly different with less maximum and minimum values. The mean of prolactin in this study was 188.61. Amballia A study was found that the mean of prolactinwas 229.6 IU/L which about 40 IU/L different from this study. The international reference range from 40 to 530 IU/L as shown in Table 2 and Figure 1. The results of this study confirmed the results of previous studies that shown that the differences in the normal values in Sudan have been documented in some hematological values, respiratory function tests parameters, Renal functions test, serum electrolytes and mean of glycated hemoglobin(Hb A1c) [18-30].

Table 2: Comparison of the Prolactin Level in Amballi A Study, Lab Reference and this Study

Figure 1: Comparison of the Prolactin Level in Amballi A Study, Lab Reference and this Study

Conclusion

There was a narrow range of prolactin level in this study 92.10-241 IU/L with lower maximum value than the international prolactin level. Prolactin decreased with age.

References

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