madman
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* We devised a formula to calculate predicted total testosterone concentrations, based on meta-analyses of individual participant data from 21,074 men, aged 17-99 years, from nine cohort studies in Australia, Europe and North America of community-dwelling men with testosterone measured using mass spectrometry (1).
* Using our testosterone calculator, we demonstrate that on average, men with high BMI and other unfavourable sociodemographic and lifestyle factors, can expect to have testosterone concentrations < 10 nmol/L (288 ng/dL) in the absence of known pituitary or testicular problems.
Aims
Existing reference ranges for circulating testosterone concentrations in men are based on its distribution in relatively small samples of healthy men, and do not consider variables such as age, height, weight, marital status, lifestyle behaviours, and medical comorbidities, all of which can influence testosterone concentrations (1). Therefore, they are blunt instruments, failing to account for the impacts of non-gonadal factors. We aimed to develop a method of predicting total testosterone concentrations for individual men, taking these factors into account.
Methods
We devised a formula to calculate predicted total testosterone concentrations, based on meta-analyses of individual participant data from 21,074 men, aged 17-99 years, from nine cohort studies in Australia, Europe and North America of community-dwelling men with testosterone measured using mass spectrometry (1). Inputs are a man’s age, height and weight (to derive body mass index, BMI), marital status, alcohol consumption, physical activity, smoking status and history of diabetes mellitus. The output is the predicted total testosterone concentration for that man, with estimated uncertainty shown as the prediction interval or PI (e.g. 80% PI).
Results
For a 30-year-old male, height 1.78 m, weight 75 kg, unmarried, with low alcohol consumption, high physical activity level, never smoked, no diabetes, BMI is 23.7 kg/m2, predicted testosterone is 18.7 nmol/L (539 mg/dL), 80% PI 11.4-26.0 nmol/L (329-749 ng/dL). If he were aged 70 years, it would be 18.4 nmol/L (530 ng/dL), 80% PI 11.2-25.6 nmol/L (323-734 ng/dL).
For a 30-year-old male with weight 120 kg and all other factors the same as above, BMI is 37.9 kg/m2, predicted testosterone is 12.8 nmol/L (369 ng/dL), 80% PI 5.6-20.0 nmol/L (161-576 ng/dL). If age and weight remain the same, but he was married, with high alcohol consumption, low physical activity level, ex-smoker, with diabetes, predicted testosterone is 9.8 nmol/L (282 ng/dL), 80% PI 2.6-17.0 nmol/L (75-490 ng/dL). For a 70-year-old, with weight of 120 kg and similar unfavourable other factors, predicted testosterone is 9.5 nmol/L (274 mg/dL), 80% PI 2.3-16.7 nmol/L (66-481 ng/dL).
Conclusion
Using our testosterone calculator, we demonstrate that on average, men with high BMI and other unfavourable sociodemographic and lifestyle factors, can expect to have testosterone concentrations < 10 nmol/L (288 ng/dL) in the absence of known pituitary or testicular problems. This could educate men, encouraging uptake of healthy lifestyle behaviours, and avoid potentially misleading diagnoses of “low” testosterone.
* Using our testosterone calculator, we demonstrate that on average, men with high BMI and other unfavourable sociodemographic and lifestyle factors, can expect to have testosterone concentrations < 10 nmol/L (288 ng/dL) in the absence of known pituitary or testicular problems.
Aims
Existing reference ranges for circulating testosterone concentrations in men are based on its distribution in relatively small samples of healthy men, and do not consider variables such as age, height, weight, marital status, lifestyle behaviours, and medical comorbidities, all of which can influence testosterone concentrations (1). Therefore, they are blunt instruments, failing to account for the impacts of non-gonadal factors. We aimed to develop a method of predicting total testosterone concentrations for individual men, taking these factors into account.
Methods
We devised a formula to calculate predicted total testosterone concentrations, based on meta-analyses of individual participant data from 21,074 men, aged 17-99 years, from nine cohort studies in Australia, Europe and North America of community-dwelling men with testosterone measured using mass spectrometry (1). Inputs are a man’s age, height and weight (to derive body mass index, BMI), marital status, alcohol consumption, physical activity, smoking status and history of diabetes mellitus. The output is the predicted total testosterone concentration for that man, with estimated uncertainty shown as the prediction interval or PI (e.g. 80% PI).
Results
For a 30-year-old male, height 1.78 m, weight 75 kg, unmarried, with low alcohol consumption, high physical activity level, never smoked, no diabetes, BMI is 23.7 kg/m2, predicted testosterone is 18.7 nmol/L (539 mg/dL), 80% PI 11.4-26.0 nmol/L (329-749 ng/dL). If he were aged 70 years, it would be 18.4 nmol/L (530 ng/dL), 80% PI 11.2-25.6 nmol/L (323-734 ng/dL).
For a 30-year-old male with weight 120 kg and all other factors the same as above, BMI is 37.9 kg/m2, predicted testosterone is 12.8 nmol/L (369 ng/dL), 80% PI 5.6-20.0 nmol/L (161-576 ng/dL). If age and weight remain the same, but he was married, with high alcohol consumption, low physical activity level, ex-smoker, with diabetes, predicted testosterone is 9.8 nmol/L (282 ng/dL), 80% PI 2.6-17.0 nmol/L (75-490 ng/dL). For a 70-year-old, with weight of 120 kg and similar unfavourable other factors, predicted testosterone is 9.5 nmol/L (274 mg/dL), 80% PI 2.3-16.7 nmol/L (66-481 ng/dL).
Conclusion
Using our testosterone calculator, we demonstrate that on average, men with high BMI and other unfavourable sociodemographic and lifestyle factors, can expect to have testosterone concentrations < 10 nmol/L (288 ng/dL) in the absence of known pituitary or testicular problems. This could educate men, encouraging uptake of healthy lifestyle behaviours, and avoid potentially misleading diagnoses of “low” testosterone.
