Biomedical subjects

J H Petersen

Publications and source records attributed to J H Petersen.

At least 19 recordsLinked to original sources

PubMed2006

A prospective study of serum insulin-like growth factor I (IGF-I) and IGF-binding protein-3 in 942 healthy infants: associations with birth weight, gender, growth velocity, and breastfeeding.

CONTEXT: Many aspects of hormonal regulation and mechanisms of normal infancy growth are poorly understood. OBJECTIVE: The objective of this study was to establish the determinants of serum growth factor levels in infancy and their association with growth. DESIGN: A prospective, longitudinal, population-based birth cohort between 1997-2001 was studied. PARTICIPANTS: Study participants were 942 healthy appropriate weight for gestational age (AGA) infants (538 boys and 404 girls) and 49 small for gestational age (SGA) children (29 boys and 20 girls). INTERVENTIONS: INTERVENTIONS were anthropometrical measurements (0, 3, 18, and 36 months) and serum samples (3 months). MAIN OUTCOME MEASURES: Height, weight, and serum IGF-I and IGF-binding protein-3 (IGFBP-3) were the main outcome measures. RESULTS: IGF-I levels showed no gender difference [boys, 92 ng/ml (confidence interval, 49, 162); girls, 91 ng/ml (47, 149); P = 0.50]. IGFBP-3 levels were significantly higher in females [2174 ng/ml (1295, 3330)] than in males [2103 ng/ml (1266, 3143); P = 0.04]. Infants receiving breast milk had lower IGF-I levels [90 ng/ml (48, 154)] than infants receiving formula [n = 62; 97 ng/ml (58, 165)] or both [n = 123; 94 ng/ml (48, 169); P < 0.001]. IGF-I and IGFBP-3 levels were positively associated with weight gain and height gain from birth to 3 months of age in AGA, but not in SGA, children. SGA children had significantly lower IGF-I [88.0 ng/ml (28, 145); P = 0.05] and IGFBP-3 [1835 ng/ml (1180, 2793); P < 0.001] levels than AGA children. CONCLUSION: We found a significant, but weak, association between IGF-I and IGFBP-3 levels at 3 months and postnatal growth in AGA, but not SGA, children. Factors other than IGF-I must contribute to the regulation of normal postnatal growth, and these may differ between AGA and SGA children. IGFBP-3, but not IGF-I, showed a gender difference, which may reflect an influence of the postnatal activation of the pituitary-gonadal axis on binding protein levels.

Biomarkers↗

PubMed2006

Migration of formaldehyde and melamine monomers from kitchen- and tableware made of melamine plastic.

Migration of one or both formaldehyde and/or melamine monomers was found in seven of ten tested melamine samples bought on the Danish market. The samples were a bowl, a jug, a mug, a ladle, and different cups and plates. No violation of the European Union-specific migration limits for melamine (30 mg kg-1) and formaldehyde (15 mg kg-1) was found after three successive exposures to the food stimulant 3% acetic acid after 2 h at 70 degrees Celsius. To investigate the effects of long-term use, migration tests were performed with two types of cups from a day nursery. Furthermore, medium-term use was studied by ten successive exposures of a plate to 3% acetic acid for 30 min at 95 degrees Celsius. The results indicate that continuous migration of formaldehyde and melamine takes place during the lifetime of these articles. The molar ratio of released formaldehyde to melamine was seen to decrease from 12 to about 5. This indicates that, first, the migration of residual monomers is most important, but in the long-term, breakdown of the polymer dominates. Two CEN methods were used to determine the concentration of monomers: a spectrophotometric method for formaldehyde and a UV-HPLC method for melamine.

Cooking and Eating Utensils↗

PubMed2005

A study of finger lengths, semen quality and sex hormones in 360 young men from the general Danish population.

BACKGROUND: It has been suggested that finger length may correlate with function or disorders of the male reproductive system. This is based on the HOXA and HOXD genes' common embryological control of finger development and differentiation of the genital bud. The objective of this study was to explore the association between the ratio of 2nd to 4th finger length (2D:4D ratio) and testis function in a sample of young Danish men from the general population. METHODS: Semen samples and finger measurements were obtained from a total of 360 young Danish men in addition to blood samples for sex hormone analysis to describe the possible association between 2D:4D and semen and sex-hormone parameters. RESULTS: A statistically significant inverse association with the 2D:4D was found only in relation to hormone levels of FSH in the group of young men with a 2D:4D >1 (P = 0.036) and a direct association with the total sperm count in the group of young men with a 2D:4D < or = 1 (P = 0.045). CONCLUSION: The statistically significant results may be 'false positives' (type I error) rather than representing true associations. This relatively large study of young, normal Danish men shows no reliable association between 2D:4D finger ratio and testicular function. Measurements of finger lengths do not have the power to predict the testicular function of adult men.

Adolescent↗

PubMed2005

Higher than expected prevalence of congenital cryptorchidism in Lithuania: a study of 1204 boys at birth and 1 year follow-up.

BACKGROUND: Cryptorchidism at birth is one of the symptoms of testicular dysgenesis syndrome (TDS). The aim of the study was to detect prevalence of cryptorchidism in Lithuanian newborn boys. METHODS: A total of 1204 consecutively born boys were examined within the first days after birth in one regional hospital. Boys cryptorchid at birth were reexamined 1 year later. RESULTS: The prevalence of cryptorchidism at birth was 5.7% (69 cases). Cryptorchidism was associated with low birth weight (P < 0.0001), preterm delivery (P < 0.0001), small gestational weight (P = 0.03) and other congenital abnormalities of genitalia (P = 0.0001). No correlation between cryptorchidism at birth and maternal age, birth order or mode of delivery was demonstrated in this study, but paternal body mass index <20 kg/m2 was found to be a significant risk factor (P = 0.001). The prevalence of congenital cryptorchidism at 1 year of age was 1.4%. CONCLUSIONS: We detected lower frequency of cryptorchidism at birth in Lithuanian boys than in Danes (9.0%), but higher than in Finns (2.4%). We had expected the frequencies in Lithuania and Finland to be relatively similar because the other symptoms of TDS (incidence of testicular cancer and semen quality) are close in these countries.

Birth Weight↗

PubMed2005

Mathematical modelling of migration: a suitable tool for the enforcement authorities?

A few years ago, it became accepted that the plastics industry could use migration modelling for compliance testing. When a calculation confirms that the migration of a compound from a plastic material or article is below the specific migration limit, this is considered sufficient documentation for compliance with legislation. In the case of non-compliance, the result needs to be verified experimentally. The European Commission recommends that the enforcement authorities use migration modelling as well to avoid long and expensive analysis. The aim of the present work was to investigate the practical possibilities of implementing migration-modelling software as a tool in official food control and possibly in improving the own-check programmes of Danish plastic-converting plants. Food inspectors from nine regional food control centres initially attended a training course in the use of a commercial modelling software package and were supported further during the project period of about 1 year. They visited 40 producers of final plastic materials and articles, but mainly due to a lack of elementary knowledge of the detailed composition of the materials only 16 full migration calculations were performed. A major reason was a lack of information from those in the raw material supply chain who considered their products protected by commercial confidentiality. In general, the food inspectors were in favour of using migration modelling for future control visits.

Commerce↗

PubMed2003

Migration of 2-butoxyethyl acetate from polycarbonate infant feeding bottles.

An enforcement campaign was carried out to assess the migration of 2-butoxyethyl acetate (2-BEA) from polycarbonate infant feeding bottles intended for repeated use. Migration was measured by three successive migration tests into two of the European Union official food simulants: distilled water and 3% acetic acid testing at 40 degrees C for 10 days. The Danish Veterinary and Food Administration (DVFA) has assessed that a migration above 0.33 mg for 2-BEA and a group of eight related substances kg(-1) foodstuff from plastics articles used exclusively for infants is unacceptable. Migration of 2-BEA was found from eight of 12 bottles. However, migration above the target value of 0.33 mg kg(-1) was not observed in the third decisive test from any of the 12 different brands of polycarbonate feeding bottles. A migration of between 0.05 and 0.26 mg kg(-1) from seven of 12 bottles was measured to 3% acetic acid in the third test, whereas no migration to distilled water was observed in the third test. The average recovery of 2-BEA after the 10-day exposure at the target value of 0.33 mg kg(-1) was 77% into distilled water and 36% into 3% acetic acid. The limited recovery was understandable as 2-BEA was partly hydrolysed in the aqueous food simulants and 2-butoxyethanol, a hydrolysis product and one of the related substances was identified. Quantification was carried out using gas chromatography after liquid/liquid extraction of the food simulant.

Acetates↗

PubMed2003

Inhibin A, inhibin B, follicle-stimulating hormone, luteinizing hormone, estradiol, and sex hormone-binding globulin levels in 473 healthy infant girls.

The early postnatal regulation of reproductive hormones seems to be more complex in girls than in boys. The aim of this study was to describe inhibins A and B, FSH, LH, estradiol, and SHBG in a large prospective cohort of 473 unselected, healthy, 3-month-old girls. In full term, appropriate-for- gestational-age girls (n = 355) hormones showed a marked interindividual variation, with concentrations up to pubertal values [medians (95% confidence intervals): inhibin B, 82 pg/ml (<20-175); FSH, 3.8 IU/liter (1.2-18.8); LH, 0.07 IU/liter (<0.05-1.07); estradiol, 31 pM (<18-83); SHBG, 137 nM (72-260)]. In 38%, FSH levels exceeded 4.5 IU/liter. Weight at 3 months had significant inverse relationships with estradiol and SHBG (P = 0.048 and P = 0.001, respectively). Gestational age was negatively correlated to estradiol (P = 0.001), with a similar trend for LH, FSH, and inhibin B. Inhibin B was higher in premature girls [126 pg/ml (<20-265)] than in term [80 pg/ml (<20-181), P = 0.002] and postmature girls [59 pg/ml (<20-152), P = 0.012]. Likewise, estradiol levels in prematures were higher than in mature girls [51 pM (<18-128) vs. 31 pM (<18-85), P = 0.009]. Estradiol was also higher in small-for-gestational-age than in appropriate-for-gestational-age girls (P = 0.046), with inhibin B and LH, but not FSH, showing a similar trend. In conclusion, reproductive hormones showed a large variation, and concentrations corresponded to those observed in puberty. Our findings support the concept of a minipuberty in infant girls similar to that in boys.

Aging↗

PubMed2002

Safety and quality of food contact materials. Part 1: evaluation of analytical strategies to introduce migration testing into good manufacturing practice.

The results of a research project (EU AIR Research Programme CT94-1025) aimed to introduce control of migration into good manufacturing practice and into enforcement work are reported. Representative polymer classes were defined on the basis of chemical structure, technological function, migration behaviour and market share. These classes were characterized by analytical methods. Analytical techniques were investigated for identification of potential migrants. High-temperature gas chromatography was shown to be a powerful method and 1H-magnetic resonance provided a convenient fingerprint of plastic materials. Volatile compounds were characterized by headspace techniques, where it was shown to be essential to differentiate volatile compounds desorbed from those generated during the thermal desorption itself. For metal trace analysis, microwave mineralization followed by atomic absorption was employed. These different techniques were introduced into a systematic testing scheme that is envisaged as being suitable both for industrial control and for enforcement laboratories. Guidelines will be proposed in the second part of this paper.

Chromatography, Gas↗

PubMed2002

Time to pregnancy in relation to semen quality assessed by CASA before and after sperm separation.

BACKGROUND: In order to provide a reference for infertile men, we defined normal values of semen quality in a population of fertile men, using computer-assisted semen analysis (CASA) before and after sperm separation. Additionally, we investigated the relationship between semen quality and time to pregnancy (TTP). METHODS AND RESULTS: Semen samples were obtained from 315 proven fertile men. The median sperm concentration in fresh samples was 107 x 10(6)/ml (5-95 percentiles: 16-322 x 10(6)/ml), the median percentage of motile sperm cells was 65% (14-87%) and the median percentage of progressively motile cells was 37% (5-64%). After density gradient sperm separation, the median total sperm count was 46 x 10(6) (4-350 x 10(6)), the median percentage of motile sperm cells was 77% (16-95%) and the median percentage of progressively motile cells was 63% (11-84%). No significant associations were found between TTP and sperm counts or sperm motility, either before or after sperm separation. This may be due in part to the fact that the study comprised couples with proven fertility. CONCLUSION: We have defined semen parameters, including the results of density gradient separation, in a population of normal fertile men which may be of interest in the evaluation of semen samples from infertile men.

Adult↗

PubMed2001

Unusual Multilayer Surface Alloy: Al(100)-c(2 x 2)-2Li.

An unusual multilayer surface alloy is formed by adsorption of one monolayer Li on Al(100). It is shown by low energy electron diffraction that the first three layers consist of a mixed Al-Li layer, a pure Al layer, and a second Al-Li layer. Thus the alloy has the same layer stoichiometry as the (100) surface of the metastable Al(3)Li bulk alloy. However, the relative orientation of the two mixed layers is the same as that in the Al(3)Ti-type structure. These findings are confirmed by total-energy calculations, which lead further to the prediction that the bulk Al(3)Li alloy has a faulted, Al(3)Ti-type surface.

Journal Article↗

PubMed2001

Embryo quality and developmental potential is compromised by age.

AIMS: The aim of this retrospective study was to assess whether and how the age of the woman affects the quality and developmental potential of the oocytes and embryos in an ART program. METHOD AND MATERIAL: A total of 878 IVF cycles was included as a consecutive series of single transfers (n=292), dual transfers (n=366) and triple transfers (n=220), where all the transferred embryos in each cycle were of identical quality score and identical cleavage stage. RESULTS: We found a highly significant decrease in oocyte recovery with increasing age with about one oocyte per 2.3 years (95% CI 1.8 years to 3.1 years, p<0.0001). Further, we found that the number of oocytes that cleaved declined significantly with increasing age with one per 3.7 years (95% CI 2.7 years to 5.5 years, p<0.0001). This decline was mainly due to the decline in number of oocytes retrieved as the ratio of aspirated oocytes that cleaved with increasing age (approx. -0.04/10 year 95% CI: -0.10; +0.009) was not significantly different (p=0.10). The percentage of transfers using fragmented embryos did not increase significantly with increasing age (p=0.08). The odds of fragmentation increased by 3% per year. The average number of embryos transferred decreased significantly (p=0.03) with age from approximately 2.1 at the age of 25 to approximately 1.8 at the age of 40. In a selected subgroup of embryos all consisting of good quality embryos, a significant decrease was found in implantation rate with increasing age (approx. -0.08/10 years, 95% CI: -1.6; +0.00, p=0.05). Of the 357 pregnancies achieved in this study we found a significantly decreased ongoing pregnancy rate and a significantly increased abortion rate with increasing age (p=0.03). The decrease in the rate of ongoing pregnancies was almost linear, decreasing by approximately 1.5% per year. CONCLUSIONS: We conclude that age has an impact throughout a woman's reproductive life and that it is important to realize that the age-related decline in fertility may start already in the late twenties and not in the mid-thirties as is generally assumed.

Adult↗

PubMed2001

Body proportions, body composition and pubertal development of children in competitive sports.

The aim of this study was primarily to investigate anthropometric variables, body composition and pubertal development in children aged 9-13 participating in competitive sports. Secondly, the influence of age, sport, training hours and pubertal development/maternal menarcheal age on body composition and pubertal development was explored. A total of 183 (96 girls, 87 boys) children performing swimming (Sw), tennis (Te), European team handball (TH), and gymnastics (Gy) took part in the study. Anthropometric measurements and pubertal development were determined. The participants completed a questionnaire regarding hours of training per week and maternal menarcheal age. Significant differences in stature (z-scores) were found in both boys (Sw=0.06; Te=0.04; TH=0.05; Gy=-0.66, P<0.004) and girls (Sw=0.12; Te=0.19; TH=0.25; Gy=-0.96, P<0.004). In girls, sum of skinfolds in millimetres (Sw=33.4; Te=33.3; TH=41.0; Gy= 27.2, P<0.02) and body mass index z-scores (SW=0.00; Te=-0.27; TH=0.35; Gy=-0.25, P<0.001) were different between the sports. A regression analysis revealed that in girls, age and maternal menarcheal age were significantly associated with pubertal development (P<0.005 and P<0.01), respectively, and sport was associated with the sum of skinfolds (P<0.05). In boys, only age was significantly associated with pubertal development (P<0.005). In conclusion, anthropometric and body composition differences exist in athletes of both sexes from different sports but are more evident in females. Most importantly, we did not find any effect of training on body composition or pubertal development, confirming previous data that children in competitive sports are selected due to constitutional factors.

Adolescent↗

PubMed2001

Thyroid function in survivors of childhood acute lymphoblastic leukaemia: the significance of prophylactic cranial irradiation.

OBJECTIVE: Focus on long-term side-effects after cancer therapy in childhood has become of the utmost importance. The hypothalamic-pituitary thyroid (HPT) axis is exposed to irradiation when some children are treated for acute lymphoblastic leukaemia (ALL) with prophylactic cranial irradiation (CIR). Whether this treatment causes hypofunction of the HPT axis remains controversial. DESIGN: We measured plasma levels of total T3 (T3), total T4 (T4) and TSH before stimulation with TRH and plasma levels of TSH, 30 and 150 minutes after stimulation with TRH in 95 patients in first continuous remission of childhood ALL. PATIENTS: Patients diagnosed with ALL before the age of 15 years between 1970 and 1991 and who were in first continuous remission and off treatment for at least one year were studied. The children were aged between 0.5 and 14.8 years (median: 3.9) at diagnosis of ALL. Thyroid function was assessed between 1.2 and 18.3 years (median: 7.6) after completion of therapy. MEASUREMENTS: We measured T4 levels before, and compared TSH levels before and after, stimulation with TRH in patients who were treated with prophylactic CIR (15-24 Gy) (n = 38) (CIR group) with patients who were treated with chemotherapy only (n = 57) (non-CIR group). RESULTS: We found that T3 and T4 levels were normal in all individuals (excluding the women who were on oral contraceptives). The median time from end of treatment to time at follow-up was 9.1 years in the non-CIR group vs. 4.2 years in the CIR group (P < 0.001), and the effect on follow-up time was significant (P = 0.04). It was estimated that just after irradiation, the TSH levels before and 30 and 150 minutes after TRH stimulation was 49% lower in the CIR group; however, after 4.0 years, TSH levels were not significantly different between the two groups. Although within normal limits, the T4 levels were significantly higher in the CIR group compared to the non-CIR group (P = 0.003). It was estimated that, just after the end of treatment, T4 was 19.9% higher in the CIR group. However, in the CIR group, the T4 level decreased significantly over time with -1.5% per year (P = 0.025), while the difference in the non-CIR group was not significant. There was no correlation between T4 and TSH levels and sex, age at diagnosis, age at the end of treatment or age at follow-up. CONCLUSIONS: We conclude that, in our cohort of survivors of childhood ALL, prophylactic cranial irradiation of the central nervous system did not have an adverse effect on hypothalamo-pituitary-thyroid function within a median follow-up time of 8 years.

Adolescent↗

PubMed2001

Regional differences in semen quality in Europe.

Recent reports have indicated a decrease in semen quality of men in some countries, and suggested regional differences. A study was undertaken of semen samples from 1082 fertile men from four European cities (Copenhagen, Denmark; Paris, France; Edinburgh, Scotland; and Turku, Finland). Semen analysis was standardized, inter-laboratory differences in assessment of sperm concentration were evaluated, and morphology assessment centralized. Lowest sperm concentrations and total counts were detected for Danish men, followed by French and Scottish men. Finnish men had the highest sperm counts. Men from Edinburgh had the highest proportion of motile spermatozoa, followed by men from Turku, Copenhagen and Paris. Only the differences between Paris/Edinburgh and Paris/Turku were statistically significant (P < 0.003 and P < 0.002 respectively). No significant differences in morphology were detected. A general seasonal variation in sperm concentration (summer 70% of winter) and total sperm count (summer 72% of winter) was detected. Semen quality of a 'standardized' man (30 years old, fertile, ejaculation abstinence of 96 h) were estimated. Typically, sperm concentrations (x 10(6)/ml) for winter/summer were: Turku 132/93; Edinburgh 119/84; Paris 103/73; and Copenhagen 98/69. These differences in semen quality may indicate different environmental exposures or lifestyle changes in the four populations. However, it remains to be seen whether such changes can account for these differences. These data may also serve as a reference point for future studies on time trends in semen quality in Europe.

Adult↗

PubMed2000

A DANREF certified reference plastic for measurement of overall migration into the food simulant olive oil by single sided testing.

A reference material for the determination of overall migration from a plastic coextrudate into the fatty food simulant olive oil was produced and certified in an interlaboratory study. The analyses were carried out according to the ENV 1186 standard from the European Committee for Standardization (CEN) [ 1, 2, 3] with exposure of the coextrudate to olive oil for 10 days at 40 degrees C. After an initial preliminary interlaboratory study eight laboratories participated in the certification round, and two different methods were used to obtain single sided exposure of the plastic to the oil. The certified value was determined as the mean of laboratory mean values. No outliers were found. A reference value of 8.6 mg/dm2 +/- 1.4 mg/dm2 (+/- half width of the 95% confidence interval) was obtained which is within the range relevant for the regulatory limit (10 mg/ dm2), making this reference material suitable for laboratories measuring according to the EU overall migration limit [4]. The material has been found stable over 45 months.

Food Analysis↗

PubMed2000

Dynamics of prey moving through a predator field: a model of migrating juvenile salmon.

The migration of a patch of prey through a field of relatively stationary predators is a situation that occurs frequently in nature. Making quantitative predictions concerning such phenomena may be difficult, however, because factors such as the number of the prey in the patch, the spatial length and velocity of the patch, and the feeding rate and satiation of the predators all interact in a complex way. However, such problems are of great practical importance in many management situations; e.g., calculating the mortality of juvenile salmon (smolts) swimming down a river or reservoir containing many predators. Salmon smolts often move downstream in patches short compared with the length of the reservoir. To take into account the spatial dependence of the interaction, we used a spatially-explicit, individual-based modeling approach. We found that the mortality of prey depends strongly on the number of prey in the patch, the downstream velocity of prey in the patch, and the dispersion or spread of the patch in size through time. Some counterintuitive phenomena are predicted, such as predators downstream capturing more prey per predator than those upstream, even though the number of prey may be greatly depleted by the time the prey patch reaches the downstream predators. Individual-based models may be necessary for complex spatial situations, such as salmonid migration, where processes such as schooling occur at fine scales and affect system predictions. We compare some results to predictions from other salmonid models.

Animals↗

PubMed2000

Identification and quantification of estrogenic compounds in recycled and virgin paper for household use as determined by an in vitro yeast estrogen screen and chemical analysis.

The use of recycled paper for the manufacture of food contact materials is widespread, but very little is known about the presence of potential contaminants in the paper. The purpose of this study was to assess the worst-case migration of estrogenic active compounds using extracts of paper for household use. Twenty different brands of kitchen rolls, nine of which were made from recycled paper and the remainder from virgin paper, were obtained from retail shops. Paper extracts were subjected to (a) determination of the total estrogenic activity by using an in vitro estrogen screen based on yeast cells stably transfected with the human estrogen receptor alpha and (b) chemical analysis and quantification by GC/MS, GC/FTIR/MS, and GC/FID for detection of a variety of estrogenic compounds. A marked estrogenic response was observed in nine of the extracts, seven of which were made from recycled paper and two from virgin paper. The chemical analysis revealed that extracts made from recycled paper contained levels of bisphenol A ranging from 0.6 to 24 mg/kg of kitchen roll, whereas extracts from virgin paper contained no bisphenol A or only negligible amounts. In contrast, 4-tert-octylphenol, 4-nonylphenols, and di-n-butyl and diisobutyl phthalate were present to a varying degree in both recycled and virgin paper with no apparent preferable distribution between the two paper types. The estrogenic response of the two extracts made from virgin paper appeared to be due partly to the presence of the preservative propyl paraben. Diisopropylnaphthalene, which turned out to be weakly estrogenic active in vitro (EC(50) = 53 microM), was detected in minor amounts in most of the extracts with the major part, ranging from 0.3 to 4.7 mg/kg of paper, found in recycled paper. Our findings that recycled kitchen rolls contain bisphenol A and other xenoestrogens may apply to other types of recycled paper used for food packaging and emphasize the importance of identifying this and other contaminants in recycled paper in general. These data indicate that bisphenol A may be useful as a purity indicator for recycled paper.

Benzhydryl Compounds↗

PubMed2000

Inter-observer variation in the results of the clinical andrological examination including estimation of testicular size.

Inter-observer variation in andrological examination by 10 clinical investigators from five Nordic and Baltic countries was investigated. In addition, information on intra-observer variation was obtained for six of the 10 investigators. Testicular size was measured using Prader's orchidometer and one of the investigators also performed an ultrasound estimate of testicular size. A highly significant difference (p < 0.001) between observers was found with an inter-observer error of 16% in estimating testicular size in 23 young men. The difference in the estimate tended to increase with increasing testicular size. There was no significant intra-observer difference in two measurements performed on consecutive days. Only differences in median testis size, which were greater than 31% between measurements by two investigators, were found to be significant at the 5% level. The ultrasound estimate of testicular size was significantly lower than the orchidometer estimate, with a mean difference of 3.6 mL for the left testis and 4.3 mL for the right testis. Tanner staging of genitalia and diagnosis of a varicocele was subject to great inter-observer variation, and for the diagnosis of varicocele only one-third of the investigators was able to reproduce their results on a second examination. In conclusion, it was found that the clinical andrological examination of young men is subject to great inter-observer variation. This should be kept in mind when results from different studies are compared as well as in daily clinical practice.

Adult↗