Michael Zitzmann

Universitätsklinikum Münster, Muenster, North Rhine-Westphalia, Germany

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Publications (136)409.41 Total impact

  • Abdulmaged M. Traish · Michael Zitzmann ·
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    ABSTRACT: Testosterone deficiency (TD) is a well-established and recognized medical condition that contributes to several co-morbidities, including metabolic syndrome, visceral obesity and cardiovascular disease (CVD). More importantly, obesity is thought to contribute to TD. This complex bidirectional interplay between TD and obesity promotes a vicious cycle, which further contributes to the adverse effects of TD and obesity and may increase the risk of CVD. Testosterone (T) therapy for men with TD has been shown to be safe and effective in ameliorating the components of the metabolic syndrome (Met S) and in contributiong to increased lean body mass and reduced fat mass and therefore contributes to weight loss. We believe that appropriate T therapy in obese men with TD is a novel medical approach to manage obesity in men with TD. Indeed, other measures of lifestyle and behavioral changes can be used to augment but not fully replace this effective therapeutic approach. It should be noted that concerns regarding the safety of T therapy remain widely unsubstantiated and considerable evidence exists supporting the benefits of T therapy. Thus, it is paramount that clinicians managing obese men with TD be made aware of this novel approach to treatment of obesity. In this review, we discuss the relationship between TD and obesity and highlight the contemporary advancement in management of obesity with pharmacological and surgical approaches, as well as utilization of T therapy and how this intervention may evolve as a novel approach to treatment of obesity in men with TD .
    Reviews in Endocrine and Metabolic Disorders 11/2015; DOI:10.1007/s11154-015-9323-2 · 4.89 Impact Factor
  • Abraham Morgentaler · Michael Zitzmann · A. M. Traish · Anthony Fox ·
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    ABSTRACT: An international expert consensus conference regarding testosterone deficiency (TD) (also known as hypogonadism) and its treatment was held on 1 October 2015, in Prague, Czech Republic. The impetus for this meeting was to address several key scientific issues that have been misunderstood or distorted during the recent intense media attention to this topic. Eighteen experts from 11 countries participated, from the disciplines of urology, endocrinology, andrology, diabetology, and basic science research. The goal was to identify scientific concepts for which there was broad agreement. It was noted that recent public controversies regarding testosterone therapy have been anchored by two retrospective studies reporting increased cardiovascular (CV) risks. Both these studies contained major flaws, and are contradicted by a large body of evidence suggesting CV benefits with testosterone therapy. Other topics discussed included the negative impact of TD on male health; the questionable validity of restrictions on treatment based on age-specific cut-offs, presence of identified underlying conditions, or application of rigid biochemical thresholds; and the lack of evidence regarding prostate cancer risks. Final consensus statements (resolutions) are under development. It is hoped these will serve as a scientific foundation for further discussion, and will thereby reduce misinformation regarding TD and its treatment.
    The Aging Male 11/2015; DOI:10.3109/13685538.2015.1106469 · 2.00 Impact Factor

  • Journal of Sexual Medicine 11/2015; 12(11):2190–2200. · 3.15 Impact Factor
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    ABSTRACT: Objective: The role of testosterone (T) in regulating body composition is conflicting, thus our goal is to meta-analyze the effects of T supplementation (TS) on body composition and metabolic outcomes. Methods: All randomized controlled trials (RCTs) comparing the effect of TS on different endpoints were considered. Results: Overall, 59 trials were included in the study enrolling 3029 and 2049 patients in TS and control groups, respectively. TS was associated with any significant modification of body weight, waist circumference and body mass index. Conversely, TS was associated with a significant reduction of fat and with an increase of lean mass as well as with a reduction of fasting glycaemia and insulin resistance. The effect on fasting glycaemia was even higher in younger individuals and in those with metabolic diseases. When only RCTs enrolling hypogonadal (total T<12 moles/L) subjects were considered, a reduction of total cholesterol as well as of triglyceride levels were also detected. Conversely, an improvement in HDL cholesterol levels as well as in both systolic and diastolic blood pressure was not observed. Conclusions: Our data suggest that TS is able to improve body composition and glycometabolic profile particularly in younger subjects and in those with metabolic disturbances. Specifically designed studies are urgently needed to confirm this point.
    European Journal of Endocrinology 11/2015; DOI:10.1530/EJE-15-0262 · 4.07 Impact Factor
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    ABSTRACT: Hypogonadism (HG, testicular failure in men) has become a controversial and much misunderstood condition. Many men perceive testosterone as a panacea for the ills of ageing and "Low-T clinics" have sprung up to meet their demands, even though testosterone is often not the answer. In light of the unprecedented rise in testosterone prescriptions in recent years, particularly amongst middle-aged men, the US Food and Drug Administration (FDA) issued a Safety Communication in May 2015 intended to restrict the use of testosterone. This article is protected by copyright. All rights reserved.
    BJU International 09/2015; DOI:10.1111/bju.13316 · 3.53 Impact Factor
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    ABSTRACT: Steroids are important physiological orchestrators of endocrine as well as peripheral and central nervous system functions. One of the key processes for regulation of these molecules lies in their enzymatic processing by a family of 5α-reductase (5α-Rs) isozymes. By catalyzing a key rate-limiting step in steroidogenesis, this family of enzymes exerts a crucial role not only in the physiological control but also in pathological events. Indeed, both 5α-R inhibition and supplementation of 5α-reduced metabolites are currently used or have been proposed as therapeutic strategies for a wide array of pathological conditions. In particular, the potent 5α-R inhibitors finasteride and dutasteride are used in the treatments of benign prostatic hyperplasia (BPH), as well as in male pattern hair loss (MPHL) known as androgenetic alopecia (AGA). Recent preclinical and clinical findings indicate that 5α-R inhibitors evoke not only beneficial, but also adverse effects. Future studies should investigate the biochemical and physiological mechanisms that underlie the persistence of the adverse sexual side effects to determine why a subset of patients is afflicted with such persistence or irreversible adverse effects. Also a better focus of clinical research is urgently needed to better define those subjects who are likely to be adversely affected by such agents. Furthermore, research on the non-sexual adverse effects such as diabetes, psychosis, depression, and cognitive function are needed to better understand the broad spectrum of the effects these drugs may elicit during their use in treatment of AGA or BPH. In this review, we will summarize the state of art on this topic, overview the key unresolved questions that have emerged on the pharmacological targeting of these enzymes and their products, and highlight the need for further studies to ascertain the severity and duration of the adverse effects of 5α-R inhibitors, as well as their biological underpinnings.
    Reviews in Endocrine and Metabolic Disorders 08/2015; DOI:10.1007/s11154-015-9319-y · 4.89 Impact Factor
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    J. Rohayem · E. Nieschlag · S. Kliesch · M. Zitzmann ·
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    ABSTRACT: In pre-pubertal boys ≥ 14 years, the differentiation between constitutional delay of growth and puberty (CDGP) and hypogonadotropic hypogonadism (HH) is challenging, as current diagnostic tools have limitations in sensitivity and specificity. The aim of this study was to assess the usefulness of markers of gonadal activity, growth axis activation and adrenarche in differentiation between pre-pubertal CDGP and HH. This retrospective study was carried out between 2006 and 2015 in an academic out-patient referral centre. The clinical data of 94 boys, aged 13.9–23.2 years and referred for “pubertal delay” were reviewed. Definite diagnoses were established on initial work-up and clinical follow-up: 24 boys were diagnosed with HH, 22 boys with CDGP, pre-pubertal (PP CDGP) at referral and 28 boys with CDGP, early pubertal at referral (EP CDGP), the latter serving as control group. Twenty patients were excluded from evaluation because of previous sex steroid treatment or associated chronic disease. Inhibin B and AMH were measured in all (n = 74); INSL3, IGF1, IGFBP3 and DHEAS in a subset of patients (n = 45) in serum of first presentation. Inhibin B and AMH were higher in boys with PP CDGP than in boys with HH: inhibin B: 87.6 ± 42.5 vs. 19.8 ± 13.9 pg/mL; p < 0.001; AMH: 44.9 ± 27.1 vs. 15.4 ± 8.3 ng/mL; p < 0.001. Receiver operating characteristics (ROC) for the diagnosis of PPCDGP vs. HH (inhibin B ≥ 28.5 pg/mL): sensitivity: 95%, specificity: 75%; AUC: 0.955. In combination with an AMH cut-off ≥20 ng/mL the specificity increased to 83%. INSL3, IGF1, IGFBP3 and DHEAS levels were not different. In boys with EP CDGP, inhibin B and IGF1 levels were highest (138.7 ± 59.9 pg/mL/289.7 ± 117 ng/mL), whereas AMH levels were lowest (11.7 ± 9.1 ng/mL). Sertoli cell markers are helpful for establishing a prognosis, whether a boy with pubertal delay will enter puberty spontaneously, whereas Leydig cell, growth and adrenal markers are not.
    Andrology 08/2015; 3(5). DOI:10.1111/andr.12088 · 2.30 Impact Factor
  • V. Nordhoff · R. K. Fricke · A. N. Schüring · M. Zitzmann · S. Kliesch ·
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    ABSTRACT: Intracytoplasmic sperm injection (ICSI) using spermatozoa from patients with severe oligoasthenoteratozoospermia is still a challenge. Although spermatozoa are available, lower fertilisation rates as well as compromised pregnancy rates are observed after ICSI. We aimed at identifying respective parameters in the pre-values of ejaculate samples used for couple counselling. The clinical pre-values of 121 patients and their corresponding 228 ICSI cycles performed between 2002 and 2010 were retrospectively analysed. Patients were divided into three groups: (i) group 1 (G1, n = 51) where all patients showed at least once <0.1 million/mL (…) and ICSI was performed using ejaculate alone; (ii) group 2 (G2, n = 14) patients had once <0.1 Mill/mL or azoospermia and a testicular biopsy before start of ICSI; (iii) group 3 (G3, n = 56) patients were azoospermic and directed immediately to testicular sperm extraction (TESE). The pre-values of G2 differed significantly from G1 in terms of volume and motility. Lutenizing hormone (LH) and follicle-stimulating hormone (FSH) values were equal in G1 and G2, but showed significant differences in comparison to G3. Testis volume was significantly higher in G3. In the corresponding ICSI cycles, the percentage of cancelled embryo transfers was highest in G3. We did not find any correlations of hormonal markers or sperm pre-values with the success rates of ICSI. In our patient cohort, spermatozoa retrieved either from ejaculate or testicular biopsies have nearly identical chances in achieving pregnancies. Patients in need of TESE before ICSI have significantly lower sperm counts. However, it is not possible to calculate threshold values as indicator for TESE. © 2015 American Society of Andrology and European Academy of Andrology.
    Andrology 08/2015; 3(5). DOI:10.1111/andr.12077 · 2.30 Impact Factor
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    ABSTRACT: Microsurgical testicular sperm extraction (mTESE), combined with intracytoplasmic sperm injection (ICSI) represents a chance for azoospermic men with Klinefelter's syndrome (KS) to father children. The objective of this study was to identify predictive factors for the success of mTESE from adolescents and adults with KS. The clinical data of 50 late pubertal adolescents (13-19 years) and 85 adult patients (20-61 years) with non-mosaic KS, who underwent mTESE, were analysed with respect to factors, potentially predictive of active spermatogenesis; specifically a history of cryptorchidism, age, testicular volumes, serum levels of LH, FSH, testosterone (T) and estradiol at the time of surgery. Inhibin B, AMH and INSL3 were additionally analysed in the adolescents. A younger age and a near-compensated Leydig cell function were associated with higher success of sperm retrieval via mTESE: In adolescents ≥15-19 years, spermatozoa were retrieved in 45%, compared to 31% in adults; in adolescents aged 13-14 years, spermatozoa were collected in only 10%. Adolescents with an LH ≤17.5 U/L, along with a T level ≥7.5 nmol/L had the best success rate (54%), which fell to 44% with higher LH, whereas those with low T (<7.5 nmol/L), irrespective of LH had no sperm retrieval. In adults with T levels above and LH below these thresholds, the success rate was 51%, falling to 19%, if LH was higher. When T was lower than threshold, the rate was 17%. No association between testicular volumes, serum levels of FSH, Inhibin B, AMH, estradiol and mTESE success was found. A history of cryptorchidism was associated with lower retrieval rates. A window of opportunity for an approximate 50% chance to retrieve spermatozoa via mTESE exists for young, late pubertal KS patients between age 15 and young adulthood, when Leydig cell function is at its best. In these cases, referral to a centre of expertise should be considered. © 2015 American Society of Andrology and European Academy of Andrology.
    Andrology 07/2015; 3(5). DOI:10.1111/andr.12067 · 2.30 Impact Factor
  • M Zitzmann · S Kliesch ·
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    ABSTRACT: Sexual functional dysfunctions represent a multidimensional nosological entity. Apart from the directly measurable pathophysiological parameters, psychological and dynamic partnership aspects are almost always involved. These can exert a triggering and a potentiating influence. Similarly, sociocultural factors have to be taken into account. In men the problem most frequently has a physiological focus and the main symptom within the complex of sexual difficulties, especially for diabetic patients, is erectile dysfunction. Disorders of ejaculation and orgasm may also occur. Testosterone production in men may be impaired due to obesity-related dysfunctions of the hypothalamic-pituitary-gonadal axis and this can lead to a clinically significant androgen deficit and thus also to a decline of libido 1 2. © Georg Thieme Verlag KG Stuttgart · New York.
    Aktuelle Urologie 07/2015; 46(4):303-308. DOI:10.1055/s-0035-1555797 · 0.16 Impact Factor
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    ABSTRACT: Introduction: In 2014, the International Society for Sexual Medicine (ISSM) convened a panel of experts to develop an evidence-based process of care for the diagnosis and management of testosterone deficiency (TD) in adult men. The panel considered the definition, epidemiology, etiology, physiologic effects, diagnosis, assessment and treatment of TD. It also considered the treatment of TD in special populations and commented on contemporary controversies about testosterone replacement therapy, cardiovascular risk and prostate cancer. Aim: The aim was to develop clearly worded, practical, evidenced-based recommendations for the diagnosis and treatment of diagnosis and management of TD for clinicians without expertise in endocrinology, such as physicians in family medicine and general urology practice. Method: A comprehensive literature review was performed, followed by a structured, 3-day panel meeting and 6-month panel consultation process using electronic communication. The final guideline was compiled from reports by individual panel members on areas reflecting their special expertise, and then agreed by all through an iterative process. Results: This article contains the report of the ISSM TD Process of Care Committee. It offers a definition of TD and recommendations for assessment and treatment in different populations. Finally, best practice treatment recommendations are presented to guide clinicians, both familiar and unfamiliar with TD. Conclusion: Development of a process of care is an evolutionary process that continually reviews data and incorporates the best new research. We expect that ongoing research will lead to new insights into the pathophysiology of TD, as well as new, efficacious and safe treatments. We recommend that this process of care be reevaluated and updated by the ISSM in 4 years.
    Journal of Sexual Medicine 06/2015; 12(8). DOI:10.1111/jsm.12952 · 3.15 Impact Factor
  • Michael Zitzmann ·

    Nature Reviews Urology 04/2015; 12(5). DOI:10.1038/nrurol.2015.73 · 4.84 Impact Factor
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    ABSTRACT: Introduction & Aim: According to standardized guidelines humans with GD receive cross-sex hormone therapy (CSHT) for up to 2 years before SRS. In order to assess the effectiveness of CSHT we evaluated changes of body constitution, testes and hormonal status in a multi-center study with 3 clinics advising different treatment strategies. Material & Methods: Following written informed consent and ethical approval, 175 testicular tissues from 114 patients were obtained from 3 German clinics. In clinic A CSHT was stopped 2 weeks before SRS, in clinic B 4-6 weeks before and in clinic C not at all. Questionnaires were handed out to patients about their CSHT. Hormone levels (LH, FSH, testosterone, estradiol, prolactin, free testosterone, SHBG) were measured with standardized in-house assays and intratesticular testosterone (ITT) levels with radioimmunoassay. Testicular tissues were histologically evaluated for spermatogenic state and tubular diameter. Leydig cell ‘functionality’ was immunohistochemically checked via LH-receptor stainings. Results: Out of 83 subjects, 59 took a anti-androgens/estrogen combination. The 3 most prominent changes of body constitution were breast growth, smooth skin, emotional instability. 20% of the testicular tissues showed complete spermatogenesis, 28% meiotic arrest, 34% spermatogonial arrest, 16% Sertoli-cell only and 2% tubular ghosts. The testicular mean weight decreased with the drop of spermatogenic progress. Subjects from clinic B showed the highest LH, FSH, prolactin, testosterone and free testosterone levels. Those from clinic C showed the highest SHBG, estradiol and ITT-levels. Whilst percentages of tubules and interstitium increased, the percentage of lumen dropped with the decrease of spermatogenic progress. The tubular diameter as well as the number of LH-receptor positive cells decreased simultaneously. Conclusion: A highly heterogeneous histological and endocrine picture was observed. Ongoing CSHT provoked highly feminized endocrine parameters in clinic C when compared to the other clinics. Hence we strongly recommend individually adapted CSHT, a close follow-up and hormonal check-ups for GD patients before SRS.
    EPATH, Ghent; 03/2015
  • A Busch · J Gromoll · S Kliesch · M Zitzmann · F Tüttelmann ·

    Experimental and Clinical Endocrinology & Diabetes; 03/2015

  • Experimental and Clinical Endocrinology & Diabetes; 03/2015
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    Dataset: EJE 2011

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    ABSTRACT: Abstract Hypogonadism or Testosterone Deficiency (TD) in adult men as defined by low levels of serum testosterone accompanied by characteristic symptoms and/or signs as detailed further on can be found in long-recognized clinical entities such as Klinefelter syndrome, Kallmann syndrome, pituitary or testicular disorders, as well as in men with idiopathic, metabolic or iatrogenic conditions that result in testosterone deficiency. These recommendations do not encompass the full range of pathologies leading to hypogonadism (testosterone deficiency), but instead focus on the clinical spectrum of hypogonadism related to metabolic and idiopathic disorders that contribute to the majority of cases that occur in adult men.
    The Aging Male 02/2015; 18(1):1-11. DOI:10.3109/13685538.2015.1004049 · 2.00 Impact Factor
  • Michael Zitzmann ·

    DMW - Deutsche Medizinische Wochenschrift 02/2015; 140(3):160-162. DOI:10.1055/s-0041-100250 · 0.54 Impact Factor
  • Michael Zitzmann · Sabine Kliesch ·

    Diabetes aktuell 01/2015; 12(08):359-365. DOI:10.1055/s-0034-1543992

Publication Stats

4k Citations
409.41 Total Impact Points


  • 2002-2015
    • Universitätsklinikum Münster
      • Centrum für Reproduktionsmedizin und Andrologie
      Muenster, North Rhine-Westphalia, Germany
  • 2001-2015
    • University of Münster
      • Center for Reproductive Medicine and Andrology
      Muenster, North Rhine-Westphalia, Germany
  • 2011
    • Brown University
      • Alpert Medical School
      Providence, Rhode Island, United States
  • 2002-2008
    • Reproductive Medicine Institute
      Chicago, Illinois, United States
  • 2006
    • Berlin-Chemie AG
      Berlín, Berlin, Germany
  • 2003
    • University Medical Center Schleswig-Holstein
      • Department of Pediatrics
      Kiel, Schleswig-Holstein, Germany