Causes and Diagnosis of Hyperhidrosis

Cause

To date, there are still no established exact diagnostic criteria for hyperhidrosis, and because patients do not visit the hospital even though they feel discomfort and do not think of it as an illness, it is difficult to know the exact prevalence. However, it is estimated to occur in about 0.6–4.6% of the total population, and the likelihood is known to be slightly higher in Asia. Symptoms of palmar hyperhidrosis appear in childhood or adolescence, while symptoms of axillary hyperhidrosis appear around puberty or in the early 20s.

There are about 1.5 million to 4 million sweat glands in the human body, combining apocrine and eccrine sweat glands. Among them, the sweat glands related to hyperhidrosis are eccrine sweat glands, of which there are about 3 million, making up most of the sweat glands. Eccrine sweat glands are mainly distributed on the palms and soles, and the total amount of sweat normally secreted is about 0.5 to 1 mL per minute, but under severe high-temperature conditions, they may secrete as much as 10 L of sweat per day. In contrast, apocrine sweat glands are fewer in number and are mainly distributed in the armpits and perineum. Apocrine sweat glands mainly secrete sweat into hair follicles and produce sticky, odorous sweat, but their effect on hyperhidrosis is minimal.

Recently, another type of sweat gland has been reported: apoeccrine sweat glands, which are mainly distributed in the armpits of adults and have the form and function of both apocrine and eccrine sweat glands. These apoeccrine sweat glands are thought to have a major effect on axillary hyperhidrosis.

The cause of primary hyperhidrosis is still not exactly known, but it is known to be related to an abnormal response of the nervous system to overactivation of the eccrine sweat glands through the autonomic nervous system and to factors that stimulate sweating. Sweating tends to worsen with emotional stress and has the 특징 of appearing suddenly and intermittently. Because large amounts of sweat appear unexpectedly and suddenly, patients, especially those with both facial flushing and hyperhidrosis, may have difficulty in social and work life, and in severe cases may show social avoidance.

In patients with hyperhidrosis, there are no histological abnormalities in the sympathetic nerves or the eccrine sweat glands themselves, but functionally, the activity of the skin's sympathetic nervous system increases in response to mental stimuli, so it is speculated that an abnormality in the hypothalamus may be the cause.

According to recent research findings, family history is known to be present in about 50% of cases, and there are also reports of an association with chromosome 14. Severe hyperhidrosis mainly occurs on the palms and soles, followed by combined occurrence on the palms and armpits, then the armpits alone or the head region.

Diagnosis

To determine the treatment method, hyperhidrosis must be confirmed and the degree of sweating must be assessed. First, it is necessary to diagnose whether hyperhidrosis is primary or secondary. Primary hyperhidrosis is defined as a condition in which a specific area has significantly excessive sweating for a period of 6 months or more without any special cause, and at least two of the following apply.

1. Bilateral and relatively symmetric distribution of sweating

2. Excessive sweating occurring at least once a week

3. Hyperhidrosis severe enough to interfere with daily life

4. Onset before age 25

5. Family history

6. No sweating during sleep

Although not widely used in clinical practice for diagnosis and assessing disease severity, a method using iodine and starch may be used to identify the areas affected by hyperhidrosis. This test is useful not only for determining the treatment area but also for evaluating the results after treatment. After cleaning and drying the skin, an iodine solution is applied and starch is sprinkled on top, and the sweating area turns dark purple. Another diagnostic method is gravimetry, which measures the amount of sweat produced, but this is also not commonly used in clinical practice. At present, questionnaire methods that score the patient's symptoms are more widely used than these physical tests.

So far, I have explained the causes and diagnosis of hyperhidrosis.

In the next part, we will look at the treatment of hyperhidrosis.

Source: Korea Disease Control and Prevention Agency, National Health Information Portal