The approach to diagnosis of primary hyperhidrosis (Hh) starts with using one or more methods of assessment of severity of sweating. Practical, qualitative, and quantitative methods are available to aid the physician in confirming the diagnosis. A logical approach to making a clinical diagnosis is presented, along with a diagnostic algorithm outlining this approach.
Assessment methods for Primary Hh
During the evaluation of a patient with primary hyperhidrosis, it is sometimes necessary to assess the rate of sweat production, the specific areas involved, and the effect of the condition on the patient’s quality of life, psycho-social wellness, and daily activities.
Some experts believe that it is important to observe the patient sweating during an office visit, however, because Hh can be episodic and unpredictable, this is not always possible and diagnosis may need to be more reliant on patient descriptions and assessment of symptoms' impacts.
If visible sweating is possible to observe:
- For axillary involvement, an assessment of the sweat stains of shirts and blouses can be useful. In some cases, a sweat stain with a diameter less than 5 cm is normal. Mild hyperhidrosis can be associated with stains 5 to 10 cm in diameter and still confined to the armpit. Stains of 10 to 20 cm are seen in moderate hyperhidrosis, while stains over 20 cm reaching the waistline are common in severe hyperhidrosis.
- For palmar hyperhidrosis, a low grade of involvement would be a moist palmar surface without visible droplets of perspiration. If palmar sweating extends toward the fingertips, the condition can be considered moderate, and if sweat drips off the palm and reaches all the fingertips, it is severe. Severity of sweating of other focal areas (craniofacial, buttocks, back, groin, under the breasts) may best be determined by patient descriptions if not visible during the time of the exam.
A quantitative approach to assessing severity is gravimetric measurement, which can be done on the palm and in the axilla (creative practitioners can likely adapt this process to other body areas, too). It is important to note that while gravimetric measurement is sometimes still utilized in clinical trials (with debatable reliability), it is not - and need not - be part of routine clinical practice.[57,63] After drying the surface, a preweighed filter paper is applied to the palm or axilla for a period of time measured by stopwatch. The paper is then weighed and the rate of sweat production is calculated in mg/min. Sweating rates in normal individuals and in patients with hyperhidrosis are presented in the table below. Because there is some overlap between patients and controls, the degree of embarrassment and effect on quality-of-life and impairment on daily activities should also be assessed in order to confirm the diagnosis.
Sweating rates by gravimetric measurement
|Anatomic area||Normals in clinical trials||Criteria for hyperhidrosis diagnosis in clinical trials|
|Men||Mean 14.4 mg/min||> 20 mg/min|
|Women||Mean 9.4 mg/min||> 10 mg/min|
Another quantitative test is evaporimetry, in which a device measures the rate of skin water vapor loss. This test has been used to assess response to treatment by both topical therapy and botulinum toxin injections for palmar hyperhidrosis.[44,95]
The Minor, or starch-iodine, test is used to assess the area involved in excessive sweating.  This test is not useful for quantifying the degree of hyperhidrosis, as there is little correlation with area of sweating and sweat rate measured by gravimetry, but is useful in determining the area requiring treatment (such as for botulinum toxin injections). In this method, a 2% iodine solution is applied to the area of interest and allowed to dry, and then starch in powder form (corn starch) is brushed on the area. The light brown iodine color turns dark purple as an iodine-starch complex forms in the liquid medium as the eccrine sweat comes to the surface of the affected area. Digital photography of the involved area allows for documentation and follow-up comparison after treatment.
Printing tests using paper impregnated with starch-iodine or spraying ninhydrin on paper applied to the sweating surface work similarly, with color changes denoting area of active eccrine sweat production. These methods can provide only a qualitative assessment of sweating, but are useful for following patients after treatment by serial photography of the involved areas.
Another approach to assessment (perhaps more practical for most practices) is the use of a quality-of-life and impairment of daily activities measurement. Possible useful instruments include: the Illness Intrusiveness Rating Scale, the Dermatology Quality of Life Index, or a disease-specific measure of quality of life such as that developed by Amir and colleagues or the HHIQ5, or the Hyperhidrosis Disease Severity Scale (HDSS).[28, 100,139] (See Condition Overview: Effects on patients’ lives.)
The International Hyperhidrosis Society offers the Hyperhidrosis Disease Severity Scale (HDSS) as a free download to be used to help with diagnosis of Hh through patient history. The validity and reliability of the HDSS have been analyzed using three studies and have been found to have strong to moderate correlations with the Hyperhidrosis Impact Questionnaire (HHIQ), Dermatology Quality of Life Index (DLQI), and gravimetric sweat production measurements.*
Approach to diagnosis
The first step in the evaluation of a patient's excessive sweating is to distinguish between primary and secondary hyperhidrosis. Therapy for secondary Hh should be directed toward the underlying causative agent or illness. A history focusing on location of excessive sweating, the duration of the problem, family history, specific triggers, a review of systems, and a review of any medications being taken by the patient should allow the physician to distinguish whether the patient has 1) generalized sweating due to an underlying systemic illness or as a side effect of a medication or 2) focal sweating due to a neurologic disorder or primary hyperhidrosis.[2,57,145]
Primary hyperhidrosis has specific and characteristic findings such that Adar and colleagues feel the diagnosis can be made on the basis of history and physical alone. These findings include its occurrence in generally young, healthy patients with a family history and onset during childhood or adolescence (facial sweating may have a later onset, however). Primary Hh patients typically will have bilateral, symmetric involvement of palms, soles, and/or axillae (or other specific body areas or body area combinations). There may also be a history for triggers (emotional and thermal stimuli), but it should be noted that that hyperhidrosis sweating can occur regardless of external temperature or external stress. As a final characteristic, patients with primary hyperhidrosis usually do not sweat during sleep.
In summary, although the Hh diagnosis can usually be made on the basis of history and observed excessive sweating, gravimetric measurement may also provide a quantitative assessment. Given the potential for overlap in sweating rates between patients with hyperhidrosis and healthy controls, it is important to gauge the severity of social embarrassment and the effects on quality of life and impairment of daily activities in order to plan treatment, especially if more than one area is involved. This information can be obtained by asking appropriate questions as part of the patient’s history and by using questionnaires or patient self-rating scales.
* A Comprehensive Approach to the Recognition, Diagnosis, and Severity-Based Treatment of Focal Hyperhidrosis: Recommendations of the Canadian Hyperhidrosis Advisory Committee, Dermatologic Surgery, August 2007, pages 908-923