The cause of the hyperhidrosis: first determine the type of hyperhidrosis
The diagnosis of primary, focal hyperhidrosis is based on interviews with affected patients, clinical findings, and further tests as necessary.
In the following, we would like to explain how the cause of the hyperhidrosis is diagnosed based on the guidelines for the definition and treatment of primary hyperhidrosis set by the German Dermatological Society (as of 1 November 2017).
The cause of secondary hyperhidrosis is usually an underlying disease.
Therefore, the focus should be on the diagnosis and treatment of the underlying disease; this is why we don’t address secondary hyperhidrosis here.
Typical signs of primary, focal hyperhidrosis
Patient interview (medical history): During the conversation with your treating physician, they will ask you some questions about your strong sweating.
The following are typical indications of primary (focal) hyperhidrosis:
- onset of symptoms in childhood, adolescence, or early adulthood (usually by age 25; with hand symptoms usually occurring before puberty)
- sweating regardless of temperature, unpredictable, and not willingly controllable
- localized occurrence in one or more sites prone to a disease with bilateral, symmetric involvement
- occurs more than once a week and impairs the quality of everyday life
- no increased sweating during sleep
- positive family history
Primary focal hyperhidrosis is a disease with no known cause. If the medical history indicates this diagnosis, there is no need for routine laboratory or imaging. The diagnosis is based primarily on the interview and clinical findings.
Determine the severity of the hyperhidrosis
As part of the clinical findings, your hyperhidrosis can be classified in terms of severity:
Level 1 (mild hyperhidrosis):
The armpits and/or hands and feet show a significantly increased skin moisture. If the armpits are affected, sweat spots 5 to 10 cm in diameter are common.
Level 2 (moderate hyperhidrosis):
Beads of sweat form on the underarms and/or hands and feet. With hyperhidrosis of the hands or feet, the sweating is still limited to the soles of the feet or the palms of the hands. If the armpits are affected, sweat spots 10 to 20 cm in diameter are common.
Level 3 (severe hyperhidrosis):
The sweat drips down from the underarms and/or hands and feet. If the hands and/or feet are affected, there will be sweat on the fingers and toes and on the sides of the hands and feet. If the armpits are affected, there are sweat spots with diameters over 20 cm.
In addition to the interview and clinical classification, the restrictions on the quality of life are also important for the diagnosis of hyperhidrosis. Therefore, your doctor may ask you questions about the impact of increased sweating on your everyday quality of life.
Test for the detection of hyperhidrosis
The diagnosis of hyperhidrosis is mainly based on the interview and clinical evaluation. In addition, two more tests can be used to diagnose hyperhidrosis: the Minor (starch iodine) test and the gravimetric measurement of sweating rates.
Minor (starch iodine) test:
the Minor test allows the sweat-secreting area, for example, in the armpit, to be identified through dyeing. For this purpose, an iodine solution is applied to the skin area and then dusted with corn starch. Areas which are sweaty turn dark blue. The test does not provide information on the severity of hyperhidrosis and is usually only used if the area of excessive sweating cannot be delimited with confidence.
The amount of sweat per unit of time can be determined by gravimetric measurement using filter paper (such as a common coffee filter), stopwatch (testing usually lasts 5 minutes), and an ultrafine scale. The sweat emitted in a certain area of skin per 5 minutes is caught in a filter paper and then weighed with an ultrafine scale. Abnormal sweating in the area of the armpit is anywhere above 50 mg per minute, while hyperhidrosis in the hands or feet is diagnosed at 20-30 mg per minute.
Both tests are also suitable for assessing the therapeutic success of tap water iontophoresis.