Low Hormone Concentrations Research Articles

Total and free thyroxine and triiodothyronine: Measurement discrepancies, particularly in inpatients

ObjectiveWe compared the performance of tandem mass spectrometry versus immunoassay for measuring thyroid hormones in a diverse group of inpatients and outpatients. MethodsThyroxine (T4), triiodothyronine (T3), free thyroxine (FT4), and free triiodothyronine (FT3) were measured by liquid chromatography tandem mass spectrometry and immunoassay in 100 patients and the two assays were compared. ResultsT4 and T3 values measured by the two different assays correlated well with each other (r=0.91–0.95). However, the correlation was less good at the extremes (r=0.51–0.75). FT4 and FT3 concentrations measured by the two assays correlated less well with each other (r=0.75 and 0.50 respectively). The studied analytes had poor inverse correlation with the log-transformed TSH values (r=-0.22–0.51) in the population as a whole. The strongest correlations were seen in the groups of outpatients (r=−0.25−0.61). The weakest degree of correlation was noted in the inpatient group, with many correlations actually being positive. ConclusionThe worst between-assay correlation was demonstrated at low and high hormone concentrations, in the very concentration ranges where accurate assay performance is typically most clinically important. Based on the lesser susceptibility of mass spectrometry to interferences from conditions such as binding protein abnormalities, we speculate that mass spectrometry better reflects the clinical situation. In this mixed population of inpatients and outpatients, we also note failure of assays to conform to the anticipated inverse linear relationship between thyroid hormones and log-transformed TSH.

Cost-effectiveness analysis on the use of rFSH + rLH for the treatment of anovulation in hypogonadotropic hypogonadal women.

BackgroundHypogonadotropic hypogonadal women are characterized by ovarian functionality deficiency, caused by low concentrations of follicle-stimulating hormone (FSH) and luteinizing hormone (LH). To recover reproduction functionality, recommended therapies for ovarian induction involve injections of FSH and LH medications.ObjectiveSince important differences exist between recombinant and urinary gonadotropin therapies in terms of efficacy and cost, the objective of this study was to develop a cost-effectiveness model to compare recombinant FSH (rFSH) + recombinant LH (rLH) and highly purified human menopausal gonadotropin (HP-HMG).MethodsA Markov model was developed, considering three cycles of therapy; probability of pregnancy and miscarriage were considered, and the efficacy was evaluated in terms of pregnancy occurrence. The perspective of the model was that of the Italian Health Service, so only direct cost (drugs, specialist visits, patient examinations, and hospitalizations) were included.ResultsrFSH + rLH is associated with a higher total cost (€3,453.50) and higher efficacy (0.87) compared with HP-HMG (€2,719.70 and 0.50). rFSH + rLH generated an incremental cost effectiveness ratio equal to €2,007.30 compared to HP-HMG; the average cost per pregnancy is estimated to be €3,990.00 for recombinant strategy and €5,439.80 for urinary strategy. Results of probabilistic sensitivity analysis were consistent with the abovementioned findings.ConclusionDespite the higher acquisition cost in comparison to HP-HMG, rFSH + rLH resulted in a higher pregnancy rate, which makes it the recommended choice when considering cost-effectiveness of LH in supporting FSH-induced follicular gonadotropins in hypogonadotropic hypogonadal women.

Menstrual cycle change in thalamic glutamate decarboxylase and GABA in response to TMJ pain in rats (726.4)

Women report TMJ pain more often than men and epidemiological evidence suggests the pain response varies between men and women and over the menstrual cycle. Recent studies show TMJ responsive neurons projecting to the thalamus have different activities in male and females. Using a rat model our lab performed whole genome array screens on thalamic tissue of cycling rats. The results indicate that the transcript of both glutamate decarboxylase 1 and 2 (GAD67 and GAD65, respectively) are significantly up‐regulated in the thalamus of proestrus (high estrogen, progesterone and luteinizing hormone concentration) versus diestrus/metestrus (low estrogen, progesterone and luteinizing hormone concentration) rats. On the other hand, GABA expression (by ELISA assay) did not significantly change in the thalamic tissue during the proestrus phase. The differences in response of the enzyme and its product could be explained by the distribution of each enzyme within individual neurons. In conclusion, sex steroids could alter thalamic GABAergic signaling to effect TMJ hyperalgesia through regulation of GAD.Grant Funding Source: Supported by NIH R01 NIDCR grant: DE022129 Estrogen and TMJ Pain

New Developments in Vaginal Rings for Contraception

Over the last few decades, new contraceptives with lower concentrations of hormones administered through different routes have been developed. The vaginal contraceptive ring is a relatively new, effective, safe, self-administered hormonal contraceptive method that is increasingly being tested and used. Vaginal rings that release new progestins and estrogens are being developed to reduce side effects and risks, and offer new choices to users. Currently, there are only two commercially available contraceptive rings: a monthly ring containing etonogestrel and ethinylestradiol (NuvaRing®) and a progesterone-only ring for lactating women that can be used for three months (Progering®). To increase the use of this method, recent and ongoing studies are testing rings with progesterone receptor modulators, estradiol and antiretroviral drugs for their indications and safety.

Effect of low thyroid hormone bioavailability on childhood cognitive development: data from the Avon Longitudinal Study of Parents and Children birth cohort

BackgroundHypothyroidism is associated with impaired cognitive development. Whether free thyroxine (T4) concentrations at the lower end of the reference range also have a negative effect is less clear. A common genetic variant, the Thr92Ala substitution in deiodinase-2 can exacerbate low free T4 concentrations by reducing intracellular conversion of free T4 to free tri-iodothyronine. We aimed to see whether low thyroid hormone bioavailability (free T4 in the lowest quartile and the Thr92Ala substitution in deiodinase-2) in childhood adversely affects cognitive development. MethodsThe data from this study come from a retrospective cross-sectional analysis in a population-based birth cohort study, the Avon Longitudinal Study of Parents and Children. Children had thyroid function tested at age 7 years and extensive cognitive assessments at age 8 years. We assessed the odds of having a lower end intelligence quotient (IQ) (<85) if an individual had low thyroid hormone bioavailability. Analyses were adjusted for age, sex, other thyroid hormone variables, and social class. Findings422 (13·5%) of 3127 children had the Thr92Ala substitution, with 116 children (3·71%) having the combination of free T4 in the lowest quartile and the Thr92Ala substitution. We noted a strong association between children with free T4 in the lowest quartile and the Thr92Ala substitution and lower mean IQ (p=0·008, t test). Individuals with free T4 in the lowest quartile and the Thr92Ala substitution were more likely to have a total IQ score below 85 than individuals with free T4 above the lowest quartile without the substitution (odds ratio 3·03, 95% CI 1·38–6·67; p=0·006). There was no association with IQ below 85 in individuals with free T4 in the lowest quartile without the substitution (1·07, 0·82–1·39; p=0·59). When we considered total IQ as a continuous variable, children with free T4 in the lowest quartile and the Thr92Ala substitution had a lower IQ than did those with free T4 above the lowest quartile without the substitution (β=−0·34, −0·64 to −0·04, p=0·03). InterpretationCommon genetic variation in the intracellular thyroid hormone action pathway seems to substantially modify the effect of low serum thyroid hormone concentrations on IQ. This finding suggests that thyroid hormone concentrations alone do not entirely reflect thyroid status and raises the possibility that thyroxine supplementation in at-risk children might improve cognitive outcomes. FundingBupa Research Foundation, British Thyroid Foundation.

TSH Prevents Bone Resorption and with Calcitriol Synergistically Stimulates Bone Formation in Rats with Low Levels of Calciotropic Hormones

Thyroid-stimulating hormone exerts both antiresorptive and anabolic effects on bone remodeling in aged ovariectomized rats and thyroid stimulating hormone-receptor null mice, supported by clinical results demonstrating that low thyroid-stimulating hormone level is associated with increased bone loss. To further explore the effect of thyroid-stimulating hormone on bone metabolism we introduced here a rat model with removed thyroid and parathyroid glands to obtain low serum concentrations of thyroid and parathyroid hormone, calcitonin and 1,25(OH)2D3. Surgery resulted in hypocalcemia, low parathyroid and thyroid hormone, 1,25(OH)2D3, C-telopeptide, and osteocalcin serum level. Intermittent administration of thyroid-stimulating hormone resulted in a further decrease of serum calcium and decreased level of serum C-telopeptide due to the suppression of bone resorption, while in the same animals osteocalcin in serum was higher indicating an increased bone formation rate. A combination of thyroid-stimulating hormone and 1,25(OH)2D3 significantly increased the serum Ca2+, C-telopeptide and serum osteocalcin values. MicroCT analyses of the distal femur and proximal tibia showed that rats treated with 1,25(OH)2D3 alone or in a combination with thyroid-stimulating hormone had an increased trabecular bone volume, and enhanced trabecular bone quality. Biomechanical testing of the trabecular bone showed an increased maximal load for 105% and 235%, respectively, in rats treated with 1,25(OH)2D3 alone, or in a combination with thyroid-stimulating hormone. We suggest that thyroid-stimulating hormone independently of calciotropic hormones suppressed bone resorption and stimulated bone formation, while in combination with 1,25(OH)2D3 acted synergistically on bone formation resulting in an increased bone volume.

Characteristics of ketoacidosis diabetic at Fatmawati Hospital

Background Diabetic ketoacidosis (DKA) is the most common complication of diabetes mellitus. DKA results from absolute or relative deficiency of circulating insulin and from combined effects of increased counter regulatory hormone levels. The combination of low serum insulin and high counter regulatory hormone concentrations accelerate catabolic state with increased glucose production by liver and kidneys (by glycogenolysis and gluconeogenesis), impair peripheral glucose utilization causing hyperglycemia and hyperosmolality, and increase lipolysis and ketogenesis, resulting in ketonemia and metabolic acidosis. Most of Indonesian children with diabetes mellitus (DM) came for the first time with diabetic ketoacidosis.

Neonatal Seizures

Neonatal seizures are a potentially life-threatening pediatric problem with a variety of causes, such as birth trauma, asphyxia, congenital anomalies, metabolic disturbances, infections, and drug withdrawal or intoxication. Thorough and timely evaluations of such patients are necessary to identify and treat the underlying etiology, therefore reducing potential morbidity and mortality. We review neonatal seizures and hypocalcemia and present the case of a 6-day-old male infant who presented to a tertiary pediatric emergency department with seizure-like episodes. He was found to have markedly low serum calcium, magnesium, and parathyroid hormone concentrations, as well as a significantly elevated serum phosphate concentration. The etiology of these abnormalities was found to be maternal ingestion of extremely high doses of calcium carbonate during the third trimester of her pregnancy, an occurrence that has been reported only once in the literature. Education pertaining to the dangers of excessive calcium carbonate intake during pregnancy may be an important piece of anticipatory guidance for pregnant mothers with symptoms of gastroesophageal reflux, and questioning the mother of a neonate presenting with seizures about such over-the-counter medications may help to elucidate the diagnosis.

Sex hormones and skeletal muscle weakness

Human ageing is accompanied with deterioration in endocrine functions the most notable and well characterized of which being the decrease in the production of sex hormones. Current research literature suggests that low sex hormone concentration may be among the key mechanism for sarcopenia and muscle weakness. Within the European large scale MYOAGE project, the role of sex hormones, estrogens and testosterone, in causing the aging-related loss of muscle mass and function was further investigated. Hormone replacement therapy (HRT) in women is shown to diminish age-associated muscle loss, loss in fast muscle function (power), and accumulation of fat in skeletal muscle. Further HRT raises the protein synthesis rate in skeletal muscle after resistance training, and has an anabolic effect upon connective tissue in both skeletal muscle and tendon, which influences matrix structure and mechanical properties. HRT influences gene expression in e.g. cytoskeletal and cell-matrix proteins, has a stimulating effect upon IGF-I, and a role in IL-6 and adipokine regulation. Despite low circulating steroid-hormone level, postmenopausal women have a high local concentration of steroidogenic enzymes in skeletal muscle.

Thyrotropin Receptor Antibody Assays

In this issue of the Journal , Leschik and colleagues1 compare the analytical performance and the clinical utility of a commercially available thyroid-stimulating immunoglobulin (TSI) reporter bioassay with an automated thyrotropin-binding inhibitory immunoglobulin (TBII) electrochemiluminescent immunoassay. The TSI reporter bioassay is a cell-based assay (or “bioassay”) that uses a genetically engineered cell line capable of specifically detecting serum TSI using cyclic AMP–dependent luciferase activity as the readout. The TBII assay is an anti–thyrotropin receptor (TSHR) electrochemiluminescent immunoassay that uses a porcine TSHR and human anti-TSHR autoantibody M22. The authors report that the TSI bioassay is able to detect lower levels of anti-TSHR autoantibodies than the TBII assay and exhibits better precision, but they do not present data indicating whether either assay is more predictive than the other in determining patients’ responses to antithyroid treatment. However, they clearly establish the sensitivity of both assays. TSHR autoantibody (TRAb) measurements (as either TSI or TBII) generally have few potential clinical applications: confirming the diagnosis of Graves disease, the prediction of risk for Graves disease in a neonate born to a mother with Graves disease in pregnancy or in the past, and the prediction of relapse in the medical treatment of Graves disease. In most patients, the diagnosis of Graves disease can be made in the clinical setting of thyrotoxicosis, diffuse goiter, ophthalmopathy (exophthalmos), and dermopathy (pretibial myxedema).2,3 The diagnosis is easily confirmed in most patients with a low thyroid-stimulating hormone (TSH) concentration and an elevated FT4 concentration. In early Graves disease, if T4 levels are normal the …

Non-genomic, direct modulatory effect of 17β-estradiol, progesterone and their synthetic derivatives on the activity of human erythrocyte CuZn superoxide dismutase

This study aimed to evaluate whether natural or synthetic steroid hormones could directly modulate the activity of the different superoxide dismutase (SOD) isoforms found in human blood fractions without changing enzyme expression. Enzyme samples of human erythrocytes, the human platelet-rich plasma fraction (PRP) or isolated CuZnSOD, which was purified from human erythrocytes were pre-incubated with natural steroids (17β-estradiol 17-acetate and progesterone) and their synthetic derivatives (β-estradiol 3-benzoate and medroxyprogesterone 17-acetate). Then, CuZn and MnSOD activities were measured using the xanthine/xanthine oxidase/nitroblue tetrazolium method. Hormones had no effect on MnSOD activity from the PRP, but we show for the first time that natural and synthetic steroid hormones have a direct, bell-shaped effect on the activity of CuZnSOD from both male and female human erythrocytes. Low (physiological) hormone concentrations caused a dose-dependent increase in enzyme activity, which disappeared at higher hormone concentrations. In addition, the combination of synthetic and natural estrogens and progestins had a synergistic stimulatory effect on the activity of CuZnSOD from human erythrocytes. The molecular interaction between CuZnSOD and steroid hormones was preliminarily studied. Natural hormones did not change the electrophoretic mobility of SOD under denaturing conditions, but they did increase the absorption spectra of SOD in the 230–290 nm range. These data suggest that hormone-mediated modulation of CuZnSOD is related to subtle changes in protein conformation, possibly related to Trp and Phe residues. We propose that this effect may account for the physiological regulation of enzyme activity during conditions where steroid hormones undergo alterations as the ovulatory cycle.

Дозозависимые эффекты стероидных гормонов на экспрессию геновGfi1иU2af1l4в Т-лимфоцитах разной степени дифференцировки

Alternative splicing of Ptprc gene is a key event in memory T cell differentiation. This gene encodes transmembrane tyrosine phosphatase CD45. One of potential mechanisms of alternative splicing regulation is based on antagonistic effects of auxiliary splicing factor U2AF26 and transcription factor Gfi1. These two proteins regulate antigen-dependent T cell activation. We have shown that steroid hormones have different effects on U2af1l4 and Gfi1 transcription regulation in dissimilar differentiation stage cell culture, subjected to antigen-independent stimulation. Low concentrations of glucocorticoid (Dex) and female sex hormone (Est) can activate expression of U2af1l4 in re-stimulated cells that probably induce terminal receptor CD45 isoforms formation mechanism, whereas high doses of hormones inhibit the process. In the same conditions Dex in a wide range of concentrations (10(-5)-10(-7) M) and Est (10(-6) and 10(-7) M) activate U2af1l4 gene expression that probably leads to "surrogate memory T cells" formation. Dose dependent testosterone (Test) effect is opposite to Est and Dex effect on priming (CD45RO+) and naive (CD45RA+) lymphocytes. The role of steroid hormones in memory T cell differentiation in antigen-independent stimulation conditions is of great interest for the understanding of chronic hormonal and immune disbalance mechanisms.

Female sex hormones and cytokine secretion in women with multiple sclerosis

Data from experimental and clinical research suggest that sex hormones may influence the autoimmune process in multiple sclerosis (MS). Studies on the hormonal profile of patients with MS and its relation to the disease activity provide heterogeneous results.Objectives: The aim of this study is to investigate the changes in serum levels of estradiol and progesterone and their correlations with the cytokine profile and the degree of disability in women with relapsing-remitting MS (RRMS).Methods: The serum concentrations of estradiol, progesterone, tumor necrosis factor-alpha (TNF-alpha), interferon-gamma (IFN-gamma), interleukine-4 (IL-4) and interleukine-10 (IL-10) were measured and the degree of disability was determined in 35 women with RRMS, during relapse and remission. Serum levels of hormones were measured by micro-particle enzyme immunoassay and ELISA was used for the cytokines concentrations. The degree of disability was assessed by the Expanded Disability Status Scale and the Scripps Neurological Rating Scale.Results: Sixty per cent of patients had serum concentrations of estradiol and/or progesterone below the lower limit of normal in one or both phases of MS. Hormonal levels increased significantly during remission in these patients. Women with and without hormonal abnormalities differed in terms of cytokine profile during relapse and remission. Significantly higher TNF-alpha in both phases and IFN-gamma in remission was found for the patients with hormonal disturbances compared to these with normal hormonal status.Conclusions: Our study finds high frequency of hormonal disturbances among female patients with RRMS. Abnormally low concentrations of sex hormones are associated with higher serum levels of TNF-alpha and IFN-gamma, which could suggest suppressive effect of estradiol and progesterone on pro-inflammatory cytokine secretion.

Assessment of theca cell function: a prerequisite to androgen or luteinizing hormone supplementation in poor responders

Poor responders are a heterogeneous population, with some patients displaying a diminished ovarian reserve and others a poor ovarian reserve with preserved granulosa cell function. Androgen and LH/hCG supplementation has been advocated for poor responders, mainly those >40 years old. Although androgens synergistically act with FSH to support folliculogenesis, and ovarian androgen secretion declines with age, there is still no evidence that androgen therapy is actually effective to improve ovarian FSH sensitivity. The main reason seems to be that theca cell function has not been appropriately assessed in patients at risk of poor response. The definition of theca insufficiency is hampered by methodologic shortcomings in routine bioassays. Provocative tests for theca cells might help to identify those patients who could benefit from androgen supplementation. The lack of data regarding theca cells in these patients might contribute to explaining the absence of evidence for a positive effect of androgen therapy.

Vegetative propagation of native species potentially useful in the restoration of Mexico City’s vegetation

Hardwood and softwood cuttings of Buddleia cordata HBK, Dodonaea viscosa Jacq and Senecio praecox D.C. were tested for their ability to form adventitious roots. Cuttings were prepared in two different seasons (wet and dry) and treated with different concentrations of auxins (IBA and NAA) and different microclimatic conditions. Hardwood and softwood cuttings of B. cordata rooted during the dry and wet season, whilst hardwood and softwood cuttings of D. viscosa rooted only in the wet season, cuttings of S. praecox rooted only in wet season with a higher rooting for hardwood than softwood cuttings. Low hormone concentrations (10 – 100 ppm) favored the rooting percentage more than high concentrations. However, high hormone concentrations favored number, and length of roots and number of developed shoots. Natural regeneration of these species is limited and the species are difficult to propagate from seeds. Vegetative propagation of the species is recommended as the source of clonal planting stock to reforest some areas of Mexico City.

Adrenal cavernous hemangioma with subclinical Cushing’s syndrome: report of a case

Cavernous hemangioma of the adrenal gland is a rare tumor, which does not usually have endocrinological function. We report to our knowledge, the third documented case of a functioning adrenal hemangioma. Interestingly, this tumor indicated glucocorticoid hypersecretion, whereas the two previous cases showed mineralocorticoid hypersecretion. The tumor was 5 cm in diameter with typical computed tomography and magnetic resonance imaging findings. Subclinical Cushing's syndrome was diagnosed preoperatively, as there was insufficient suppression of cortisol by low-dose dexamethasone, a low adrenocorticotropic hormone (ACTH) concentration, and diminished ACTH and cortisol circadian rhythms without the typical clinical manifestation and symptoms of hypercortisolism. Intraoperative hypotension occurred immediately after tumor removal and following postoperative adrenal insufficiency, which support that the tumor was hyperfunctioning. The postoperative adrenal insufficiency had recovered completely by 12 months after the operation.

Presumptive nonthyroidal illness syndrome in critically ill foals

Hypothalamic-pituitary-thyroid (HPT) axis dysfunction is associated with morbidity and mortality in critically ill people. To date, investigations of HPT axis in critically ill foals are limited. To document the occurrence of low thyroid hormone concentrations (presumptive nonthyroidal illness syndrome; NTIS) in critically ill newborn foals and investigate whether NTIS is associated with severity of disease and outcome. NTIS occurs frequently in foals with sepsis and is associated with sepsis score and outcome. Reverse T3 (rT3) concentrations will be increased in septic foals and highest in nonsurvivors. Thyroid hormones (total and free thyroxine [TT4 and fT4], total and free tri-iodothyronine [TT3 and fT3], reverse T3 [rT3]) were prospectively measured in healthy, sick nonseptic and septic foals. Clinical and laboratory information was retrieved from the medical records. Hormones were measured by validated radioimmunoassays. Concentrations of all thyroid hormones except rT3 (P = 0.69) were decreased in septic and sick nonseptic foals (P < 0.01). Reductions in hormone concentrations were associated with an increased sepsis score (P < 0.01). Nonsurviving septic foals had lower TT4, fT4, TT3 and fT3 concentrations than surviving septic foals (P < 0.01). rT3 concentrations were higher in nonsurviving septic prematurefoals than surviving septic premature foals (P < 0.05). NTIS (euthyroid sick syndrome) is frequently observed in critically ill and premature foals, and associated with severity of disease and mortality. More research is needed to better understand the mechanism of this finding and determine whether manipulation of the HPT axis or thyroid replacement therapy could be beneficial.

Salivary Hormone Measurement Using LC/MS/MS: Specific and Patient-Friendly Tool for Assessment of Endocrine Function

Saliva has recently been attracting attention as a patient-friendly available bio-fluid and an alternative to serum/plasma for hormone tests. LC coupled with atmospheric pressure ionization-MS/MS, especially electrospray ionization (ESI)-MS/MS, has been recently valued as a highly specific method in the analysis of salivary hormones. In this article, LC/ESI-MS/MS assays for salivary hormones are overviewed according to the papers that have been published during the last 5 years. Practical derivatization to enhance the detectabilities of hormones in ESI-MS/MS is also discussed, because a major disadvantage of using saliva is low hormone concentrations.

Unpredictable endocrinology of the menopause transition: clinical, diagnostic and management implications

The approach to menopause can be divided into the early (E) and late (L) menopausal transitions (MT) on the basis of menstrual irregularity (EMT) and subsequent observation of at least one episode of 60 or more days amenorrhoea (LMT). In total, 40-60% of cycles in the LMT are anovulatory, often with low oestradiol (E2) and high follicle-stimulating hormone concentrations. The ovulatory cycles have variable endocrine characteristics, none of which is specific to EMT or LMT. Hormonal measurements of FSH and E2 are thus of little diagnostic value because of their unpredictable variability. Symptoms during the transitions may result from high or low E2 and can often be satisfactorily managed with low-dose oral contraceptives, which suppress pituitary-ovarian function.

The Effects of Oral Contraceptive Use on Muscle Stiffness Across the Menstrual Cycle

To determine the effect of oral contraceptives (OC) on hamstring neuromechanics and lower extremity stiffness across the menstrual cycle (MC). Causal comparative. Research laboratory. Thirty, healthy, normally menstruating female volunteers who were using OC (OC group, n = 15) or not (non-OC group, n = 15). Stiffness and hamstring neuromechanics were assessed at 2 points of the MC corresponding to low (menses) and high (ovulation) hormone concentrations. Menses testing took place 3 to 5 days after the onset of menses (or pills 3-5 for the OC group). Ovulation test session occurred 2 to 4 days after ovulation identified using a commercial ovulation kit (or pills 15-17 in the OC group). Lower extremity stiffness and hamstring neuromechanics [stiffness, electromechanical delay, rate of force production (RFP), time to 50% peak force (T50%)] and blood plasma concentrations of estradiol-β-17, free testosterone, and progesterone. Estradiol-β-17, free testosterone, and progesterone increased at ovulation in the non-OC group and remained constant in the OC group. No changes were observed across the MC or between the groups in other variables (P > 0.05). Although previous literature suggests a prophylactic effect of OC use with respect to musculoskeletal injury risk, our results indicate that OC use does not affect muscle properties in manners thought to reduce ACL injury risk.