The white line test of Sergent is one of the oldest methods for assessing cutaneous-vascular reaction. It was proposed by the French physician Emil Sergent in 1917 and was long used as an indirect sign of so-called hypoaldrenism.
Today it is known that this test does not reflect adrenal function, but it can provide insight into the skin’s reaction and the autonomic nervous system.
Test Description
The method is based on observing the change in skin color after light mechanical irritation. Normally, the capillaries dilate, and a red line appears on the skin. In some conditions, instead of reddening, the skin reacts with persistent pallor.
How to Perform the Test
- choose a skin area on the abdomen without irritations or damage;
- take a pen or another blunt object and draw a line about 15 cm long;
- observe the color of the line for the next few seconds;
- note whether the line turns red or remains white;
- assess the duration of the white color if it appears.
How Results Are Typically Interpreted
In the classical description of the test, it was considered that the normal reaction is a rapid reddening of the skin due to capillary dilation.
If the line remains white for 60 seconds to two minutes, such a reaction was interpreted as a manifestation of reduced vascular tone and weak skin response.
In alternative literature, this was associated with “adrenal fatigue,” but modern data do not support this interpretation.
Why the Test Does Not Indicate Adrenal Fatigue
The white line on the skin is a manifestation of white dermographism. It arises for reasons that are not directly related to cortisol or adrenal function. Skin reaction is influenced by histamine processes, the state of capillaries, the sensitivity of the autonomic nervous system, hydration levels, and the characteristics of the skin cover.
The appearance of the white line is also common in atopic dermatitis, allergic reactions, autonomic dysfunction, and increased skin sensitivity. These factors explain the reaction much more accurately than hormonal changes.
What the Test Really Shows
- features of the skin’s vascular reaction;
- the state of the autonomic nervous system;
- increased or decreased skin sensitivity;
- features of the histamine response;
- disruption of local capillary tone.
It can help understand the overall reactivity of the skin, but it cannot serve as a tool for diagnosing hormonal disorders.
