Hyperhidrosis

Diagnosis

Most patients see a dermatologist for excessive sweating. Your doctor will start the diagnostic process with a physical exam. If you have hyperhidrosis, the doctor likely will see sweat droplets on your body, even when you aren't anxious and have a normal heart rate and blood pressure. The doctor will ask about family history. Large studies have shown that 25 to 50 percent of patients with palmar hyperhidrosis have a family history of the disorder.

A thermoregulatory sweat test, before surgery (top) and after surgery.

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Blood tests are used to rule out serious conditions that can cause sweating, such as hyperthyroidism, diabetes, acromegaly (a growth hormone disorder), and pheochromocytoma, a tumor of the adrenal gland.

For severe hyperhidrosis, your doctor may recommend tests that pinpoint the spots where sweating originates. This information is helpful when considering and implementing treatment options.

Minor-starch iodine test

In this test, an iodine solution is applied to the skin along with dry starch powder. In areas where sweating is excessive, the powder turns dark blue. Your doctor measures the volume of sweat by applying sensitive filter paper to the blue regions for 60 seconds. The filter papers are then weighed to determine the rate of sweat production. This test helps determine the severity of hyperhidrosis and response to treatment.

Thermoregulatory sweat test

In the thermoregulatory sweat test, which was developed by Mayo Clinic doctors, your skin is covered with a moisture-sensitive powder that changes color — from yellow-orange to dark purple — in areas of excessive sweating. Powder color changes are recorded first at room temperature with a digital camera, which determines the severity and extent of primary hyperhidrosis.

Then, you'll be taken to a tented heating cabinet, where humidity and temperature are increased. Color changes are again recorded. This documents heat-induced (thermoregulatory) sweating.

Patients who have primary hyperhidrosis tend to sweat even more in the palms in a warm environment. Those who don't have hyperhidrosis tend not to sweat in the palms. These findings help your doctor accurately diagnose and define the severity of hyperhidrosis and determine the optimal treatment. Occasionally, a patient will have excessive sweating on other regions of the body caused by another condition (secondary hyperhidrosis) that needs to be diagnosed and treated.

This test is available at Mayo Clinic's site in Minnesota.