Liquid chromatography–mass spectrometry applications for quantification of endogenous sex hormones

Liquid chromatography, coupled with tandem mass spectrometry, presents a powerful tool for the quantification of the sex steroid hormones 17‐β estradiol, progesterone and testosterone from biological matrices. The importance of accurate quantification with these hormones, even at endogenous levels, has evolved with our understanding of the role these regulators play in human development, fertility and disease risk and manifestation. Routine monitoring of these analytes can be accomplished by immunoassay techniques, which face limitations on specificity and sensitivity, or using gas chromatography–mass spectrometry. LC–MS/MS is growing in capability and acceptance for clinically relevant quantification of sex steroid hormones in biological matrices and is able to overcome many of the limitations of immunoassays. Analyte specificity has improved through the use of novel derivatizing agents, and sensitivity has been refined through the use of high‐resolution chromatography and mass spectrometric technology. This review highlights these innovations, among others, in LC–MS/MS steroid hormone analysis captured in the literature over the last decade.     

New approach for measurement of non-SHBG-bound testosterone in human plasma

Testosterone (T) circulates in the blood tightly bound to sex hormone-binding globulin (SHBG) and weakly to albumin. Measuring protein unbound T (free) or non-SHBG-bound T rather than total T has been recommended for the evaluation of androgen disorders in humans. Ammonium sulfate precipitation has been widely used to separate [SHBG-T] complex from free and albumin-bound T. To achieve more specificity in this separation, we used monoclonal anti-SHBG antibody and developed a suitable and convenient immunoassay for measuring non-SHBG-bound T. Magnetic beads were covalently coupled to a monoclonal anti-SHBG antibody to capture [SHBG-T] complex from plasma samples. Magnetic separation was then performed to allow measurement of non-SHBG-bound T in the supernatant by direct radioimmunoassay. When 300 μL of plasma samples were incubated at room temperature with 10 μL of anti-SHBG beads, residual SHBG concentration was undetectable in the supernatant. The specificity of proteins retained on anti-SHBG beads was further demonstrated by peptide mass fingerprint on a MALDI-TOF analyzer. The non-specific adsorption of T on beads was low (5%), and dissociation of T from SHBG-T complex was less than 5% after 180 min of incubation. The plasma concentrations of non-SHBG-bound T using anti-SHBG beads were highly correlated to those obtained using ammonium sulfate precipitation. We conclude that SHBG immunocapture is a highly specific and useful tool for an experimental direct measurement of plasma non-SHBG-bound T. This methodology is also convenient and appropriate for routine and automated assay.     

A FACTOR(S) PRODUCED BY SERTOLI CELLS STIMULATES ANDROGEN BIOSYNTHESIS BY LEYDIG CELLS IN NEONATAL RATS

Using a coculture system, we have studied the local action of Sertoli cells on Leydig cell function. The results show that (ⅰ) both LH and FSH have equal potency to stimulate testosterone biosynthesis by fetal and neonatal testicular cells in an age-dependent manner, the maximum stimulation is observed between D_3 and D_5. (ⅱ) An FSH-dependent factor(s) secreted by Sertoli cells increases the basal and/or LH-stimulated Leydig cell androgen production. (ⅲ) The Sertoli cell-stimulating factor(s) is not a steroid or other small molecule, but a heat-labile peptide.     

A robust LC–MS/MS assay with online cleanup for measurement of serum testosterone

Accurate measurement of low levels of testosterone is critical for diagnosis and treatment of androgen disorders. The very low concentrations of testosterone in children, females, and males with androgen suppression therapies necessitate the use of mass spectrometry‐based methods. We aimed to develop a liquid chromatography with tandem mass spectrometry method with simplified sample preparation and online solid‐phase extraction cleanup to achieve enhanced precision, accuracy, robustness, and cost‐effectiveness. The assay was linear from 10 to 20 000 pg/mL with an analytical recovery of 93–104%. The total coefficient of variation was 2.5, 1.9, and 1.7% at concentration levels of 348, 5432, and 10 848 pg/mL, respectively. No significant carryover was observed from samples with concentrations up to 20 000 pg/mL. No significant interference was observed from androstenedione, dehydroepiandrosterone, epi‐testosterone, and estriol. Comparison with CDC Hormone Standardization program (HoSt) reference samples with defined values (n = 40) showed a Deming regression slope of 0.963, intercept of 28.06 pg/mL, standard error of estimate was 66.9, a correlation coefficient of 0.9996, and a mean bias of ?0.6%. The method met the accuracy criteria by the CDC HoSt program. In addition, we achieved >12 000 injections on a single analytical column without significant performance deterioration due to the specific online solid‐phase extraction settings.     

睾酮电化学检测的研究进展

睾酮作为人体内一种重要的类固醇激素,在调节和促进人体机能等方面发挥着重要作用。睾酮的检测因在临床诊断和体育运动等方面具有重要作用而备受关注。该文对目前睾酮的主要检测方法进行了概述,包括常规仪器分析、免疫学检测方法和电化学检测方法,并对电化学方法特别是电化学免疫传感器对睾酮的检测进行了综述和展望。     

A Preliminary Investigation of the Solution Complexation of 4-Sulphonic calix[n]arenes with Testosterone

The complexation between water soluble calixarenes and testosterone has been studied. Stability constants of the host guest complexes of 4-sulphonic calix[n]arenes (n = 4, 6 and 8) with testosterone in water and buffers (pH 5.8, 7.3 and 10.0) were determined from phase solubility curves. These solubility curves indicated that the complexes were all of the A_L type. The constants were in the range 26–341 M^-1, dependent on the size of the calixarene and the pH of the solutions.     

吖啶酯标记的化学发光免疫分析优化参数评价

以睾酮-3-羧甲氧基肟-牛血清白蛋白为免疫原,免疫家兔产生抗血清,10-甲基吖啶-9-羧酸[4-(N-睾酮-3-羧甲氧基肟)-氨乙基]苯酯为示踪化合物,采用平衡法建立睾酮化学发光免疫分析,数据用四参数Logistic函数处理。方法学考核标准曲线稳定,R为0.9967;ED50为82.15ng/L;批内和批间CV分别为5.78%和3.3%;平均回收率为107.28%;可测范围为19.3～264.6ng/L,与雌酮、雌二醇、雌三醇和孕酮的交叉反应率均小于1.35%;非特异结合率为9.64%.“桥效应”分析表明同位点、“桥”结构相同亲和力最大.     

Study of neonatal exposure to androgenic endocrine disruptors, testosterone and dihydrotestosterone by normal-phase HPLC

Neonatal exposure to androgen induces developmental abnormalities in the male reproductive system. To investigate whether neonatal exposure affects spermatogenesis in juvenile and pubertal testis, Sprague-Dawley rat pups were given androgen or various androgenic endocrine disruptors by a single injection on the day of birth at concentrations ranging between 4 mm to 200 mm, and sacrificed on day 21 (juvenile) or 50 (puberty). The testes were weighed and examined histologically at each stage. Further, the metabolites of steroidogenesis were analyzed using normal-phase high-performance liquid chromatography. Neonatal exposure significantly reduced testis weights and steroidogenesis of juveniles. Neonatal exposure to testosterone and dihydrotestosterone still suppressed pubertal steroidogenesis, although testis weight was completely restored during puberty.     

高速逆流色谱法分离和测定甾体激素

用自制的高速逆流色谱仪分离两酸睾丸素和氢化可的松注射剂，以氯仿－甲醇－水为溶剂体系及优化的色谱条件，对样品组分作了有效的分离，以苯甲酸为内标，获得令人满意的定量结果，标准偏差小于０．８％。