Perspiration is an amazing and efficient cooling mechanism that modulates our body temperature; the lack of it forces dogs to pant and migrating birds to seek cooler climes. But perspiration can sometimes be too much of a good thing. For between two and 10 percent of the population, hyperhidrosis - excessive sweating - can be embarrassing, uncomfortable and even prevent them from working in certain professions - as cooks, physicians, electronics assemblers, computer technicians and drivers. Primary hyperhidrosis usually begins in adolescence, and tends to run in families but is not necessarily hereditary; secondary hyperhidrosis may be due to a disorder of the thyroid or pituitary gland, diabetes, tumors, gout, menopause or certain drugs. Now Dr. Ofer Landau, a specialist in general and laparoscopic surgery at Wolfson Medical Center in Holon, has written what is reportedly the first and only Hebrew-language book on hyperhidrosis. The 64-page Haza'at Yeter: Kol Hapitronot Vehatipulim, part of Prolog's Bari Lada'at series on health (www.medbook.co.il), explains the causes and various treatments in a no-nonsense style, without illustrations or gimmicks but in a way that can be understood by laymen. AS THE largest concentrations of sweat glands are located in the palms of the hands, soles of the feet and the armpits, (with others on the forehead, back, abdomen and groin), these are the sites responsible for the discomfort of hyperhidrosis patients. When the hands are involved, the condition is called palmar hyperhidrosis; the armpits is axillary hyperhidrosis; and the feet is plantar hyperhidrosis. Scientists still do not understand the exact cause of excessive sweating in specific individuals, but perspiration is known to be controlled by the sympathetic nervous system. The human body has two different sets of nerves: the somatic nervous system of voluntary nerves that allow us to move and feel sensation (such as touch, pain and heat or cold) and the involuntary autonomic system, which regulates heartbeat, respiration and the production of sweat to regulate body temperature. The autonomic system is divided, in turn, into the parasympathetic and sympathetic system, and it is the latter that controls sweating. Landau notes that the existence of pores in the skin, through which sweat is excreted, was first reported in the 17th century, and only in the 19th century were the sweat glands discovered by Bohemian researcher Jan Evangelista Purkinje. The average person has between two and four million sweat glands at a concentration of between 100 and 200 per square centimeter, but some people have three or four times that many. Their production is small in children, but around adolescence, the amount of sweat each gland produces soars, and remains steady through middle age; in old age, it declines toward pre-adolescent levels. Sweat itself does not have any odor, but bacteria and fungi on the skin cause the well-known smell when the microbes feed on sweat. FOR YEARS, writes Landau, it was thought that perspiration is a straightforward process - the filtration of liquids from the circulatory system and their excretion. But in the past two decades, it has become clear that the process is not so simple. The sudomotor section of the brain controls body temperature regulation, and the neurotransmitter acetylcholine is involved in the overstimulation of nerves that "turn on" the sweat glands. Straight sections of the tubes that form the glands are responsible for absorption of chlorine and sodium, while sweat - which also contains urea, lactate, hydrogen and potassium - is excreted from the tangled parts via the pores. Excessive sweating is sometimes triggered by stress, emotion or exercise, but can also occur spontaneously. In 1977, Tel Aviv University neurology Prof. Amos Korczyn and colleagues reported for the first time that only 0.6% to 1% of hyperhidrosis cases are due to emotion. But whatever the cause, the results are very unpleasant. Those with axillary hyperhidrosis sweat profusely from their underarms, causing them to stain their clothes shortly after getting dressed. Plantar hyperhidrosis leads to moist socks and shoes and to foot odor, while people with the palmar variety often avoid social contact so they are not forced to shake hands and be "found out." Since hyperhidrosis patients commonly get nervous because they sweat - and then sweat more when they are nervous - it is often a vicious cycle. THE FIRST step in managing hyperhidrosis is talking to a doctor about the condition, which can be treated but not completely cured. While only a doctor can prescribe or perform certain treatments, there are many things one can do to reduce the discomfort: Bathe daily to keep the amount of bacteria on your skin in check; dry yourself thoroughly after bathing; if you have sweaty feet, use powders or absorbent insoles; apply antiperspirant twice daily (better at night than in the morning if only once a day); wear airy clothing made from natural fabrics such as cotton, silk and wool, and when you exercise, try high-tech fabrics that wick moisture away from your skin; wash your clothes and change them often, and plantar-type patients shouldn't wear the same pair of shoes every day; avoid hot beverages, caffeine, alcohol and spices that can make you sweat. If you're overweight, since hyperhidrosis can be aggravated by obesity, losing weight can help, but most people with hyperhidrosis do not sweat excessively due to obesity. As for treatment, Landau advises beginning with simple, non-invasive methods. Deodorants merely cover odor, while antipersirants actually clog up the pores to prevent sweat from being secreted. These are based mostly on aluminum chloride (hexahydrate), which irritates sensitive skin. Hyperhidrosis sufferers need at least a 15% aluminum chloride solution, which is more effective on armpits but less so on feet and hands. Hypnosis, acupuncture, psychotherapy and relaxation techniques such as biofeedback, yoga or meditation can help people control the stress that can trigger perspiration. A more aggressive possibility is iontopheresis, a treatment of electrical stimulation, usually of the hands but less often of the feet and underarms. For palmar hyperhidrosis, the hands are placed in a device that has two pails of water with a conductor in each one. The hand or foot acts like a conductor between the positively and negatively charged pails. As the low current passes through the area, the minerals in the water clog the sweat glands, limiting the amount of sweat released. However, to be beneficial iontopheresis must be done regularly, although the longer the technique is used, the less effective it is. ONE OF the more recent innovations, approved by the US Food and Drug Administration and the Health Ministry, is injection of botulinum toxin (Botox) into the affected area. It reduces the nerve impulses to the sweat glands and usually requires several injections in the palms or underarms. Botox is the same toxin used for minimizing facial wrinkles - and just as temporary, lasting for an average of seven months but ranging between three and 17. There are also some oral anticholinergic drugs - such as the antidepressant Zoloft and oxybutynin - that have been shown to reduce hyperhidrosis. But taking them can cause side effects such as drowsiness and dry-mouth, forcing the patient to decide whether the treatment is more annoying than the problem. Then, for the really desperate, there is surgery, which involves destroying or removing a specific ganglion of the sympathetic nerve that causes sweating in the arm and armpits. These can be physically removed, cauterized, severed or clipped, depending on the training and preferences of the surgeon. No specific technique has been clearly proven superior to the others. Recent advances in technology have produced less invasive methods such as endoscopic thoracic sympathectomy (ETS), performed under general anesthesia. A few tiny incisions are made below the armpit, and an endoscope attached to a miniature video camera is passed through them to locate the relevant sympathetic chain. To "disarm" the ganglia, the patient's lung is collapsed to allow adequate space for the surgeon to maneuver, and later it is re-expanded. Patients are typically hospitalized for up to a day, and medications for pain are given for a week to 10 days. Aside from the risks of any type of surgery, the most common complication of ganglion removal is compensatory sweating in up to 60% of patients. Since sweating is meant to regulate the body's heat, the cessation of sweating in the upper chest, back and arms due to the surgery can lead to more sweating elsewhere (face, abdomen, back, buttocks, thighs or feet). Expert estimate that this is a nuisance for most post-operative patients who encounter it, but severe in 5% to 10% of the rest. There is also a small risk (1%) of Horner's syndrome, in which the highest sympathetic ganglion is damaged during surgery, causing a slight droop in the eyelid, a small or narrow pupil and a lack of sweating on that side of the face. It is sometimes reversible, but may prove to be permanent. These rather hair-raising descriptions alone may cause the reader to sweat - but victims of hyperhidrosis will consider invasive treatments that offer the possibility of a more normal life.