Falsely Elevated Serum Testosterone Concentrations Due to Application of Testosterone Gel Near the Phlebotomy Site

 

Clinical and laboratory features:

(1) A patient is applying testosterone gel on the skin.

(2) Gel was applied at or near a phlebotomy site prior to blood collection.

(3) The gel was not washed off prior to the phlebotomy.

(4) The serum testosterone concentration is abnormally high.

(5) Repeat testing from another site shows a much lower serum concentration.

 

This could be missed if the elevation is minor.

 

Consequences:

(1) The patient may have a reduction in the dose.

(2) Serum levels may appear to show unexplained fluctuations.