Testicular Volume

[Michael Scally MD]

Oh JK, Kim KT, Yoon SJ, Kim SW, Kim TB. Second to fourth digit ratio: a predictor of adult testicular volume. Andrology. http://onlinelibrary.wiley.com/doi/10.1111/j.2047-2927.2014.00256.x/abstract

It has been suggested that second to fourth digit ratio (digit ratio) may correlate with male reproductive system function or disorders. This hypothesis is based on finding that the Hox genes control finger development and differentiation of the genital bud during embryogenesis. Thus, we investigated the association between digit ratio and adult testicular volume.

A total of 172 Korean men (aged 20–69 years) hospitalized for urological surgery were prospectively enrolled. Patients with conditions known to strongly influence testicular volume were excluded. Before determining testicular volume, the lengths of the second and fourth digits of the right hand were measured by a single investigator using a digital vernier calliper. Using orchidometry, the testes were measured by an experienced urologist who had no information about the patient's digit ratio. To identify the independent predictive factors influencing testicular volume, univariate and multivariate analyses were performed using linear regression models.

Age, height, serum testosterone and free testosterone level were not correlated with testicular volume. Digit ratio, along with weight, was significantly correlated with testicular volume (right testicular volume: r = −0.185, p = 0.015; left testicular volume: r = −0.193,p = 0.011; total testicular volume: r = −0.198, p = 0.009). Multivariate analysis using linear regression models showed that only digit ratio was the independent factor to predict all (right, left and total) testicular volumes (right testicular volume: β = −0.174, p = 0.023; left testicular volume: β = −0.181, p = 0.017; total testicular volume: β = −0.185, p = 0.014).

Our findings demonstrated that digit ratio is negatively associated with adult testicular volume. This means that men with a higher digit ratio may be more likely to have smaller testis compared to those with a lower digit ratio.

 

[Ozzy619]

I've read a couple of your articles in regards to digit ratio, I believe the last one was about penis size. I had to research and find exactly what you were talking about, but its very interesting. If I understand it correctly, a longer ring finger and shorter index finger would give you a lower digit ration?

For those that don't know what digit ratio is:
http://en.m.wikipedia.org/wiki/Digit_ratio

 

[Michael Scally MD]

Ruiz-Olvera SF, Rajmil O, Sanchez-Curbelo JR, Vinay J, Rodriguez-Espinosa J, Ruiz-Castañé E. Association of serum testosterone levels and testicular volume in adult patients. Andrologia. http://dx.doi.org/10.1111/and.12933

A retrospective observational study was undertaken to gain new insight into the relationship between total testicular volume and levels of serum testosterone, luteinising hormone, follicle-stimulating hormone, prolactin and clinical variables.

A total of 312 men with sexual dysfunction or infertility were divided into groups A and B (156 each) on the basis of basal plasma testosterone ≤5 nmol/L of ≥12 nmol/L respectively. Group A was subclassified in A1 (primary hypogonadism) and A2 (secondary hypogonadism).

There were significant differences in total testicular volume between group A (15.33 ± 11.94 ml) and group B (36.74 ± 6.9; p < .001) and also between subgroup A1 (11.07 ± 8.49 ml) and subgroup A2 (23.62 ± 13.04 ml; p < .001). Only 13.5% of patients in group B had a total testicular volume <30 ml.

Differences in all studied parameters were found between group A and group B. There were no variations when comparing age, body mass index and testosterone in groups A1 and A2.

The use of total testicular volume and body mass index together for predicting testosterone levels yields a sensitivity and specificity of 85.3% and 86.5% respectively.

Logistic regression analysis, univariate and multivariate models, using the measurement of total testicular volume resulted in a high capacity to predict testosterone levels.

 

[Michael Scally MD]

Right Testicular Volume Is a Dominant Predictor of Testicular Function Determined by Sperm Parameters and Total Testosterone

This study aims to evaluate the predictive value of left testicular volume (LTV) and right testicular volume (RTV) for testicular function respectively. Men who requested fertility testing for any reason were enrolled from December 2012 to November 2015. Subjects with primary scrotal diseases or a condition interfering reproductive system were excluded.

Testicular volume (TV) was evaluated by scrotal ultrasound. Sex hormone and semen analysis including sperm concentration (SC) and sperm motility rate (SMR) were performed. Statistical analysis including comparison, stepwise linear regression and logistic regression was used.

Two hundred and seventy-four patients with oligoasthenozoospermia/low testosterone and 27 control subjects were enrolled. Both LTV and RTV positively correlated with testicular function, and no differences were found between bilateral TV. RTV is the best independent factor associated with testicular function determined by SC (β=.292, p < .001), SMR (β=.227, p < .001) and total testosterone (TT) (β=.245, p < .001). Using a RTV value of 15.47 ml, the highest discriminating sensitivity and specificity were 66.7% and 62.4% respectively.

RTV (<15 ml) was the only positive predictor for low testicular function (odds ratio=2.79, 95% confidence interval: 1.18–6.66; p =.020). RTV rather than LTV is the independent factor of overall testicular function determined by semen quality and TT levels. Further studies are needed to support and elucidate the difference in volume-function between bilateral testes.

Huang YP, Liu W, Liu YD, et al. Right testicular volume is a dominant predictor of testicular function determined by sperm parameters and total testosterone. Andrologia. Right testicular volume is a dominant predictor of testicular function determined by sperm parameters and total testosterone

 

[Michael Scally MD]

A Simulation Study Assessing the Accuracy and Reliability of Orchidometer Estimation of Testicular Volume

Summary Context Measuring testicular volume (TV) by orchidometer is the standard method of male pubertal staging. A paucity of evidence exists as to its inter- and intra-observer reliability and the impact of clinicians? gender, training and experience on accuracy.

Objective Prosthetic testicular models were engineered to investigate accuracy and reliability of TV estimation.

Design Simulation study.

Setting Conducted over three-day 2015 British Society for Paediatric Endocrinology and Diabetes (BSPED) meeting.

Participants 215 meeting delegates (161F, 54M): 50% consultants, 30% trainees, 9% clinical nurse specialists, 11% other professionals. Intervention Three child-sized mannequins displayed latex scrotum containing prosthetic testicles of 3ml, 4ml, 5ml, 10ml and 20ml.

Demographic data, paediatric endocrinology experience, TV examination training, examination technique and TV estimations were collected. Delegates were asked to repeat their measurements later during the meeting. Scrotum order was changed daily.

Main outcome measure Accuracy by variance from the simulated TV. Inter- and intra-observer variability.

Results 1284 individual estimations were obtained. Eighty-five participants repeated measurements. Delegates measured TV accurately on 33.4% (±2.6) of occasions: overestimations 37.7% (±2.3), underestimations 28.7% (±1.8) (Fleiss Kappa score 0.04). The accuracy of assessing a 4 ml testis was 36-39%.

Observers underestimated the volume when paired with a 3ml testes and overestimated when paired with a 5 ml testis demonstrating a tendency impose biological symmetry.

Intra-observer reliability was lacking; individuals giving different estimations for the same size testicle on 61% (±4.2) of occasions, 20% (±3.5) of estimations were more than 1 size outside the previous measurement.

On only 39% (±4.2) of occasions did individuals agree with their previous estimation (irrespective of whether or not it was initially accurate). Training did not impact on results but experience did improve accuracy.

Conclusions Overall TV estimation accuracy was poor. Considerable variation exists between and within subjects. Seniority slightly improved measurement estimation.

Elder CJ, Langley J, Stanton A, et al. A Simulation Study Assessing the Accuracy and Reliability of Orchidometer Estimation of Testicular Volume. Clinical Endocrinology 2018. https://doi.org/10.1111/cen.13923