Testosterone threshold, assay and costs among laboratories for hypogonadism diagnosis

The diagnosis of testosterone deficiency (hypogonadism) requires documentation of low testosterone concentration. Despite the thresholds for low testosterone established by various guidelines, non-expert physicians rely on reference ranges provided by laboratories. The objective of this study was to determine the consistency of laboratory-established reference ranges for total testosterone (TT) among Mexico City clinical laboratories.

Information was requested from 202 laboratories in Mexico City in August 2024. The items of interest included the TT reference ranges, equipment, assays, and costs.

The responses were obtained from 134 laboratories. There were 27 different sets of reference ranges used in this study. The high TT threshold ranged from 400 to 1,719 ng/dL (variability: 487%), whereas the lower limit ranged from 84 to 470 ng/dL (variability: 426%). Five measurement methods were described, and the most frequently used was chemiluminescence 69 (51.11%), followed by electrochemiluminescence 25 (18.65%). The cost ranged from $9-160 USD, with a mean of $35 USD.

The extreme variability in laboratory-established TT reference ranges represents a major challenge for the appropriate diagnosis and management of men with symptomatic testosterone deficiency. Although these results were obtained in Mexico City, there is good reason to believe that this problem exists globally.