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Year : 1990  |  Volume : 56  |  Issue : 1  |  Page : 15-17

State of hydration and electrical conductance of ichthyotic skin

Correspondence Address:
A B Gupta

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Dry skin of twelve subjects suffering from ichthyosis vulgaris and the efficacy of a moisturiser-Cotaryl were quantitatively assessed by measuring the skin surface hydration and high frequency (3.5 MHz) electrical conductance of skin. The state of hydration and conductance of ichthyotic skin were 86.9 + 24.6 and 11.0 + 5.7 micro-mho respectively, being much less-compared to 132. 0 + 5.3 and 72.5 + 54.0 micro-mho ofnormal subjects. The moisturiser increased the state of hydration and also the electrical conductance of the stratum corneuni to near-normal values and maintained them as long as the application continued. However, both the hydration and the conductance fell sharply within a week of withrawal of the moisturiser. A moisturiser was thus undoubtedly efficacious in ichthyotic skin, but the effect was only temporary. The state of hydration was found, at all stages, to bear a strong positive correlation (r = 0.69 to 0.80) with the skin conductance.

Keywords: Hydration, Electrical conductance, ichthyotic skin

How to cite this article:
Gupta A B, Bhattacharya M, Haldar B. State of hydration and electrical conductance of ichthyotic skin. Indian J Dermatol Venereol Leprol 1990;56:15-7

How to cite this URL:
Gupta A B, Bhattacharya M, Haldar B. State of hydration and electrical conductance of ichthyotic skin. Indian J Dermatol Venereol Leprol [serial online] 1990 [cited 2021 Jan 22];56:15-7. Available from:

The skin of subjects suffering from ichthyosis vulgaris is characterised by dryness. But the term dry skin has not been defined. However, there is a general acceptance that it is the result of a decreased water content of the horny layer.[1] It was in this context that the present study was undertaken. We assessed quantitatively, the state of hydration and the high frequency electrical conductance of the stratum corneum of ichthyotic patients and also evaluated the effect of Cotaryl R, an emollient cream of urea (12% w/w) with natural moisturising factors, upon that condition.

  Materials and Methods Top

Twelve patients of both sexes and aged 16 to 68 years, having ichthyosis vulgaris and com­plaining of dry skin of moderate to severe intensity on the limbs participated in the study.

At the first visit, the state of hydration and skin conductance at the shins of the patients were determined. Then Cotaryl R was applied twice daily on the shins and the evalu­ations were made at weekly intervals for three weeks. Measurements were made at least 12hours after the last application of the moisturiser. At the end of the third week, the moisturiser was completely withdrawn and, at the end of the fourth week, the hydration state and the electrical conductance were redetermined. We also evaluated the same two parameters under similar environmental conditions of temperature and humidity for 15 normal subjects of both sexes and in the same age group.

The hydration state of stratum corneum was measured with a Corneometer CM 820 R (Courage and Khazak_a, Koln, FRG). It consists of a console housing and a humidity sensing probe. Tile value appears as a maximum 3-digit figure on a 40 x 18 mm display. The method is based on the fact that the dielectric constant of water varies considerably and a suitably-shaped measuring capacitor reacts, according to the water-content, with the various changes of capacity to samples brought about into its measuring volume. The variations of the probe capacitor are automatically recorded by the device. The display records a value between 0-10 when the sensing probe is in contact with dry air and 150-160 with a completely moist palm.

The skin conductance was measured at a frequency of 3.5 MHz with a Skicon 200 R (IBS Co, Tokyo, Japan). This is an improved model of Skicon 1008, the description and the measuring principle of which was reported previously.[2]

The ambient temperature ranged between 26°C and 31°C and the relative humidity between 72 to 88%.

  Results Top

[Table - 1] shows the hydration level and the electrical conductance of ichthyotic and normal skin.

It is seen that while the hydration level of the normal skin was 132.05.33, it was only 86.9± 24.6 for the ichthyotic skin. As the application of the moisturiser continued, the hydration level was found to increase and was maintained more or less constant between 120 to 125 which was close to the value for normal skin. The normal skin also showed a much higher value for the electrical conductance, 72.5+54.0 micro-mho, compared to the ichthyotic skin having a value 11.0±5.7 micro-mho. With the application of the moisturiser the skin conductance, like the hydration level, was also found to increase and was maintained at a fairly high value between 57.6 to 74.6 micro-mho which agreed almost to that of the normal skin.

The situation however changed abruptly on withdrawal of the moisturiser. After one week of the withdrawal, both the hydration level and skin conductance sharply diminished to values 81.9+21.4 and 18.3±16.1 micro-mho respecti­vely, which were rather close to the corresponding pretreated values.

[t is to be noted that the coefficient of variation in skin conductance was much higher compared to that of the hydration level.

  Comments Top

The water content of ichthyotic skin, as evaluated by the state of hydration and skin conductance is found to be rather low compared to that of normal skin. This is in agreement with the studies of Tagami et al,' but is in variance with those conducted by Pierard 3sub who did not find any abnormality in conductance of dry skin. He however did not work with ichth­yosis vulgaris but studied xerosis appearing during winter. Significant modifications in the stratum corneum have been observed with time after the application of the moisturiser. It not only brought the state of hydration and the skin conductance to near-normal condition but also made a simultaneous improvement in the texture of stratum corneum as assessed by clinical evaluation. The use of moisturiser thus appears undoubtedly efficacious in ichthyosis vulgaris. However, the reversal to almost the pretreatment values soon after the withdrawal of the moisturiser shows that the effect is only temporary.

The hydration state and skin conductance are spectacularly influenced immediately on application of water onto the skin surface due to its sorption by the stratum corneum.[3] But the modification thus introduced by water was found by us to disappear within an hour by the sorption-desorption test of Tagami et al.[4] So the effect of CotaryP ;, although temporary, was not simply due to water contained in it.

The conductance data correlated strongly positively (r-0.69 to 0.80) with the hydration data at all stages-before treatment, at the end of each of the three weeks during treatment and at the end of the week after withdrawal. This was rather expected.

  References Top

1.Tagami H, Masatosmi G, Ewatsuki K et al Evaluation of the skin surface hydration in vivo by electrical measurement, J Invest Dermatol, 1980: 75 : 500-507.  Back to cited text no. 1    
2.Moseley H, English JSC, Coghill GM et al Assessment and use of a new skin hygrometer, Bioengineering and the Skin, 1985; 1 : 177-192.  Back to cited text no. 2    
3.Pierard GE : Assessment of environmental dry skin, Bioengineering and the Skin, 1986; 2: 31-37.  Back to cited text no. 3    
4.Tagami H, Kanamaru Y, Inoue K et al : Water sorption-desorption test of the skin in vivo for functional assessment of the stratum corneum, J Invest Dermatol, 1982; 7S : 425-428.  Back to cited text no. 4    


[Table - 1]


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