INTERPRETATION We found weak correlation between signs , symptoms and testosterone levels , uncertainty about what threshold testosterone levels should be considered low for aging men and wide variation in estimated prevalence of the condition .
It is therefore difficult to extrapolate the method of diagnosing pathologic hypogonadism in younger men to clinical decisions regarding age-related testosterone decline in aging men
BACKGROUND Physicians diagnose and treat suspected hypogonadism in older men by extrapolating from the defined clinical entity of hypogonadism found in younger men .
We conducted a systematic review to estimate the accuracy of clinical symptoms and signs for predicting low testosterone among aging men .
Identification of late-onset hypogonadism in middle-aged and elderly men.
BACKGROUND The association between aging-related testosterone deficiency and late-onset hypogonadism in men remains a controversial concept . We sought evidence -based criteria for identifying late-onset hypogonadism in the general population on the basis of an association between symptoms and a low testosterone level . METHODS We surveyed a r and om population sample of 3369 men between the ages of 40 and 79 years at eight European centers . Using question naires , we collected data with regard to the subjects ' general , sexual , physical , and psychological health . Levels of total testosterone  were measured in morning blood sample s by mass spectrometry , and  free testosterone levels  were calculated with the use of Vermeulen 's formula . Data were r and omly split into separate training and validation sets for confirmatory analyses . RESULTS In the training set , symptoms of poor morning erection , low sexual desire , erectile dysfunction , inability to perform vigorous activity , depression , and fatigue were significantly related to the testosterone level . Increased probabilities of the three sexual symptoms and limited physical vigor were discernible with decreased testosterone levels ( ranges , 8.0 to 13.0 nmol per liter [ 2.3 to 3.7 ng per milliliter ] for total testosterone and 160 to 280 pmol per liter [ 46 to 81 pg per milliliter ] for free testosterone ) . However , only the three sexual symptoms had a syndromic association with decreased testosterone levels . An inverse relationship between an increasing number of sexual symptoms and a decreasing testosterone level was observed . These relationships were independently confirmed in the validation set , in which the strengths of the association between symptoms and low testosterone levels determined the minimum criteria necessary to identify late-onset hypogonadism . CONCLUSIONS Late-onset hypogonadism can be defined by the presence of at least three sexual symptoms associated with a total testosterone level of less than 11 nmol per liter ( 3.2 ng per milliliter ) and a free testosterone level of less than 220 pmol per liter ( 64 pg per milliliter )
INTERPRETATION We found weak correlation between signs , symptoms and testosterone levels , uncertainty about what threshold testosterone levels should be considered low for aging men and wide variation in estimated prevalence of the condition .
It is therefore difficult to extrapolate the method of diagnosing pathologic hypogonadism in younger men to clinical decisions regarding age-related testosterone decline in aging men
BACKGROUND Physicians diagnose and treat suspected hypogonadism in older men by extrapolating from the defined clinical entity of hypogonadism found in younger men .
We conducted a systematic review to estimate the accuracy of clinical symptoms and signs for predicting low testosterone among aging men .