男性精液品質之環境危險因子探討

研究背景：精液品質是男性生育力的關鍵指標，研究指出精液品質近數十年來出現下滑的趨勢，而且會因地區、種族、環境及生活型態不同而有所差異。臺灣為高度工商業化且近數十年生活型態有劇烈變化的國家。本研究希望藉由收集近十年男性精液品質資料，分析血液中重金屬及賀爾蒙濃度瞭解臺灣男性精液品質的現況及造成低精液品質與低生育力之相關風險因子。研究目的： 1. 瞭解北臺灣2000-2010年男性精液品質現況與變化趨勢。 2. 探討男性低精液品質與鉛暴露之關係。 3. 探討精液品質、鉛暴露與男性生育力之關係，並提供台灣男性精液品質參數的參考。材料與方法：第一部分收集生殖醫學中心2000-2010年數據，分析北台灣男性精液品質的變化趨勢，第二部分採橫斷式研究，以結構式問卷調查受試者的基本人口學資料、社經狀況、工作史及醫療史，並採集血液樣本分析血中重金屬與賀爾蒙的濃度，同時分析男性精液品質，探討男性低精液品質與鉛暴露的關係。第三部分為病例對照研究法，病例組為低生育力男性，對照組為正常生育力組以結構式問卷調查受試者的基本人口學資料、社經狀況、工作史、醫療史及生育情況，採集血液樣本分析血中重金屬與賀爾蒙的濃度，探討男性生育力與鉛暴露的關係，並利用以ROC（Receiver operator characteristics）曲線分析，以提供台灣男性精液品質參數的參考。結果：臺灣男性近十年精液品質有隨年齡下降的的趨勢，包括：精液量、精子活動力（向前活動力及快速向前活動力）及精子正常型態比例。精液品質也隨年代有下降的趨勢。血中鉛濃度升高時會增加低精液品質的風險，高血中鉛濃度的男性（>5 μg/dL）較低血中鉛濃度的男性（≤5 μg/dL）有11倍的低精液品質的風險。此外，精子活動力（全活動力與向前活動力）低於World Health Organization (WHO)參考值的男性，有顯著的低生育力，其他精液品質參數與男性生育力間無顯著相關性。利用ROC曲線分析台灣男性正常與低生育力之最佳切點為65%，而當男性精子正常型態低於65%時，會有11倍的低生育力的風險。討論與結論：本研究發現精子活動力有年齡與世代效應，即精子活動力均回隨著年齡或世代的增加而下降，而在個案血中鉛濃度都低於美國CDC的建議值且FSH都在正常範圍之下，仍然可以發現血中鉛與FSH濃度都與低精液品質有顯著的負相關。另外也發現低總活動力與低向前活動力精子比例是低生育力的危險因子，並發現臺灣男性當正常精子型態比例低於65%時會增加低生育力的風險，建議未來應該收集更大樣本數繼續探討，以找出適合臺灣男性之正常精子品質參數的參考值。本研究結果希望可以提供臨床應用與公共衛生上提供臺灣男性精液品質資料的參考。

關鍵字

精液品質；鉛； ROC 曲線

並列摘要

Semen quality is a key indicator of the male reproductive ability. The decline in semen quality has been debated for several decades. However, this decline might be inconsistent given factors such as geographical area, ethnicity, environmental exposure, and lifestyle changes. Taiwan is an urbanized and industrialized island, where pollution is a pressing problem. In addition, lifestyle-related factors, such as dietary patterns and obesity, have changed tremendously in recent years. This study aimed to provide information on the semen quality of Taiwanese men by analyzing semen parameters between 2001 and 2010. In addition, we evaluate the levels of heavy metals and reproductive hormones in the blood to clarify the relationship between these factors and semen quality or subfertilty. Objective: 1. To understand the status and trends of semen quality from 2000 to 2010 in North Taiwan men. 2. To understand the relationship between lead and low semen quality. 3. To understand the relationship among metal, semen parameters, and fertility, and determine the values of suitable sperm parameters for Taiwanese men. Method: We recruited 7187 male participants between 2001 and 2010 from a reproductive medical center to provide information on the semen quality of Taiwanese men. In cross-sectional study, we collected demography information and measured the levels of metals and reproductive hormones in the blood. To determine the association between blood lead levels and low semen quality. In case-control study, we examined the blood lead (Pb) levels and semen quality in the fertile and subfertile men. In addition, receiver operating characteristic (ROC) curve analysis was used to determine the cutoff values of suitable sperm parameters for Taiwanese men to achieve spontaneous pregnancy. Result: Increasing age (per year) was significantly and negatively associated with semen volume, progressive sperm motility, rapid progressive sperm motility, and sperm with normal morphology. In addition, all semen parameters were reduced with year by year of recruitment. We observed that the increased blood Pb levels were significantly and positively associated with low semen quality. High blood Pb levels ( 5 g/dL) had an 11-fold risk of low semen quality. Our data also suggest that low percentages of total and progressively motile sperms were significant risk factors for subfertility. In addition, the percentage of sperms with normal morphology had a higher ROC curve area (0.87), and the new cutoff point for the percentage of sperms with normal morphology was determined to be 65% and those having <65% of sperms with normal morphology had an 11.35-fold higher risk of subfertility. Disscision and Conclusion: In this study, age and cohort effect on reduced the progressive and rapid progressive sperm motility. Even blood Pb levels lower than the reference level of the CDC and FSH levels were within the normal recommended range, we observed that the increased blood Pb levels were significantly and positively associated with low semen quality. In addition, low percentages of total and progressively motile sperms were significant risk factors for subfertility. Moreover, the new cutoff point for the percentage of sperms with normal morphology (65%) should be determinated with larger sample size in future. This information will be of use in clinical practice and public health investigations of the male reproductive health.

並列關鍵字

semen quality ； lead ； ROC curve

參考文獻

Agency for Toxic Substances and Disease Registry, A., 2005. Toxicological Profile for Lead. US Department of Health and Human Services, Atlanta.

Google Scholar

Anis, T. H., et al., 2007. Chronic lead exposure may be associated with erectile dysfunction. The journal of sexual medicine. 4, 1428-34; discussion 1434-6.