Pathophysiology
There are 2 types of sweat glands - apocrine and eccrine.
Apocrine glands are found mainly in the arm-pits and around the anus. The account for 10-40% of the regional sweat glands. They are not active until puberty and are involved in pheromone production but not really in temperature regulation. They are stimulated by sympathetic nerves that release adrenalin.
Eccrine glands are found everywhere on the body but have the highest concentration on the palms and soles. They consist of a secretory coil connected to the skin surface by a duct and are involved in temperature control. They are stimulated by sympathetic nerves that release acetyl-choline. Exercise and anxiety will trigger these glands to produce sweat.
Sweating is triggered by a rise in body temperature or by anxiety (the common trigger in patients with hyperhidrosis). The causes of hyperhidrosis can be considered in 2 groups:
Essential focal hyperhidrosis - the cause is unknown. It may be due to abnormal function in the sympathetic nerves. 30-50% of cases have a family history.
Generalised hyperhidrosis - this has many possible causes:
 | Temperature |
| Exercise |
| Fever |
| Fear / anxiety |
| Various cancers |
| Overactive thyroid |
| Diabetes |
| Nausea |
| Nerve injuries |