Anhidrosis or hypohydrosis is a dysfunction in which a person is unable to sweat when they are hot. Anhidrosis refers to the complete absence of sweating, while hypohidrosis is when a person sweats less than normal.
Sweating allows heat to be released from the body. If people cannot sweat properly, they cannot cool themselves, and this can be harmful.
If the condition affects a small area of the body, it is not usually dangerous, but anhidrosis or hypohidrosis of the entire body can result in overheating and eventually heatstroke, a potentially life-threatening condition. A person may not realize they have the condition until it is serious.
Contents of this article:
Signs and symptoms of anhidrosis
Anhidrosis or hypohydrosis is a dysfunction in which a person is unable to sweat.
Anhydrosis may affect one part of the body only, two or more parts, or the whole body.
The most common signs and symptoms associated with anhidrosis are:
- Abnormally poor or lack of sweating in response to heat or exertion
- Dizziness and weakness
- Sensitivity to raised temperatures, due to an inability to cool down.
People in whom just part or parts of the body are affected may find that the unaffected parts sweat excessively, to try to compensate. One part of the body may be completely dry, while another is wet.
If most of the body is affected, physical exertion or hot temperatures may lead to heat cramps, heat exhaustion or heatstroke.
Causes of anhidrosis
Anhidrosis occurs when the body's sweat glands do not work properly or at all.
Possible reasons include:
- Trauma to the nerves that control sweating
- Ross syndrome, a rare disorder of sweating associated with an absence of reflex and tonic pupil (a disorder that affects the pupil of the eye)
- Amyloidosis, a group of diseases in which one or more organ systems accumulate deposits of abnormal proteins known as amyloid
- Diabetic autonomic neuropathy, in which sweating is lost due to damage to the nervous system from poorly controlled glucose
- Long-term alcohol abuse, which can lead to alcoholic neuropathy
- Sjogren's syndrome, a chronic disorder of the immune system
- Lung cancer, which can cause anhidrosis on one side of the body and excessive sweating (hyperhidrosis) on the other
- Horner syndrome, caused by damage to the sympathetic nervous system in the neck
- Skin conditions or skin damage, including severe burns and leprosy
- Trauma to the sweat glands
- Systemic sclerosis, or scleroderma, a group of rare chronic, progressive autoimmune diseases in which connective tissues and the skin harden and tighten
- Plugged sweat gland ducts due to dead skin or bacterial infections.
- Graft-versus-host disease, in which immune cells from a bone marrow donor attack the bone marrow transplant recipient's sweat cells.
If people cannot sweat properly, they cannot cool.
A number of medications can lead to anhidrosis.
Antimuscarinic anticholinergic agents have a number of applications. They are sometimes used to control some of the side-effects of antipsychotics, as also known as neuroleptics or major tranquilizers. Examples include benzhexol, benztropine, biperiden, orphenadrine, and procyclidine.
Carbonic anhydrase inhibitors are used as antiglaucoma agents, diuretics, and antiepileptics. They can also help manage osteoporosis, duodenal and gastric ulcers, mountain sickness, and some neurological disorders. Examples include acetazolamide, methazolamide, dorzolamide, and topiramate.
What is dehydration?
Dehydration is when the body loses more fluids than it takes in because of diarrhea, vomiting, profuse sweating, frequent urination, skin burns, being at high altitude, or endurance sports, such as marathons.
Anhidrosis can be a symptom of severe dehydration.
Dehydration can normally be reversed by taking in fluids, but in severe cases, medical intervention may be necessary.
Alcohol consumption can lead to dehydration, unless the person also drinks plenty of water.
In an emergency situation, the health care team will take measures to cool the patient and administer fluids to stabilize him or her.
Tests may be carried out to confirm the diagnosis and rule out possible conditions or illnesses.
A quantitative sudomotor axon reflex test (QSART) measures the autonomic nerves that regulate sweating.
It can assess disorders of the autonomic nervous system, peripheral neuropathies, and some other types of pain disorders.
Electrodes filled with acetylcholine are placed on the wrist and different areas of the leg. Mild electrical stimulation is applied to the skin (iontophoresis), and acetylcholine, a naturally-occurring chemical, enters the skin. Acetylcholine stimulates the sweat glands, and sweat responses are measured.
A silastic sweat imprint test also uses electrodes, but pilocarpine is given to stimulate the sweat glands. An imprint of the sweat droplets appears as indentations on a material made of silicone rubber.
A thermoregulatory sweat test assesses the thermo-regulatory sudomotor pathway of the whole body, and it measures sweat production in relation to an increase in core temperature.
The patient's body is coated with alizarin red powder. When moist, the powder changes color from orange to purple.
To monitor core temperature, a is inserted into the patient's mouth. To detect excessive surface heating, a thermal device is placed on the skin. The patient enters a chamber that is heated by infrared heating units. Temperature and humidity are carefully controlled.As the patient sweats, or not, the whole body is photographed. Computer scanning technology maps the areas of anhidrosis.
A biopsy may help to examine the sweat glands and skin cells.
Treatment options for anhidrosis
People who do not sweat enough when doing exercise are at risk of developing heat stroke.
Treatment will focus on the underlying condition that causes the anhidrosis.
Patients with anhidrosis in only a small part of their body might not require any treatment.
Medications that have been reported to help include prednisolone, a corticosteroid and injection of a local anesthetic into the sympathetic nerve tissue in the neck.
If the cause is unknown, treatment options are limited. People with the condition should avoid activities and environments that raise their core body temperature, and exercise should be done in a cool place, and preferably under supervision.
Anhidrosis, hypohidrosis and heat stroke
People who do not sweat enough, or at all, when doing exercise or in hot environments are at risk of developing heat stroke.
Heat stroke is a medical emergency that can cause damage to the brain and the internal organs. It can be fatal.
If a person develops heat stroke, it is important to call 9-1-1 and keep them as cool as possible.