Skin Barrier Properties in Different Body Areas in Neonates
Gil Yosipovitch, MD*; Ayala Maayan-Metzger, MD‡§储; Paul Merlob, MD‡§储; and Lea Sirota, MD‡§储
ABSTRACT. Objective. The aim of the study was to investigate skin barrier function in neonates in different anatomic sites during the first 2 days of life.
Design. The study population consisted of 44 healthy full-term newborn infants. Transepidermal water loss (TEWL), stratum corneum hydration (SCH), and skin sur-face pH were measured in different anatomic sites (fore-head, flexor part of forearm, upper back, abdomen, in-guinal region, palms, and soles) during the first 10 hours of life and 24 hours later. Measurements were recorded with a Tevameter, a Corneometer, and a skin pH meter with a flat glass electrode. Results were compared with those in 20 healthy adults.
Results. TEWL was lower in infants than in adults in the forehead, palms, soles, and higher in the forearms. It was significantly higher on day 1 than on day 2 in the soles, palms, and forearms, and in the forearm, palms, and inguinal region compared with the other anatomic sites. SCH was significantly lower in the infants on the forehead, back, and abdomen, and higher on the fore-arms and palms; it was significantly higher on the first day of life on the forearms and palms, and lower in the inguinal region. Skin surface pH was significantly higher in the infants in all body sites (>6.6 in most measurements). On day 2, it was significantly lower than on day 1, but still higher than in adults. SCH correlated positively with TEWL in the neonates but not in the adults. None of the variables were related to gestational age, sex, mode of delivery, or body weight.
Conclusions. Changes take place in SCH, water loss, and pH in the first 2 days after birth, suggesting that the stratum corneum barrier is still in the process of adapting to extrauterine life. The significant anatomic variability in TEWL and SCH should be taken into account in eval-uating the permeation of skin care products and topical medications in newborns.Pediatrics2000;106:105–108; stra-tum corneum physiology, neonate skin barrier function, transepidermal water loss.
ABBREVIATIONS. TEWL, transepidermal water loss; SCH, stra-tum corneum hydration.
T
he most important function of the skin is to act as a barrier, preventing dehydration from the loss of body water, poisoning from the absorp-tion of drugs and chemicals, and systemic infecabsorp-tionfrom invading surface microorganisms.1,2 Although
preterm infants (gestational age: ⱕ32 weeks) are known to have impaired skin barrier function1,2
com-pared with term infants, the properties of the vari-ables relevant to skin barrier function in different body areas during the first days of life have barely been investigated. In 1 study of infants with trans-epidermal water loss (TEWL), the technique of choice for evaluating skin barrier function,3 no
dif-ferences were found among 3 regional sites,4in
con-trast to reports in adults.5,6In addition, studies have
shown that the stratum corneum acidifies during the first week of life.7 Because the skin has to perform
vital functions immediately after birth, such as ther-moregulation, dessication, and protection against damage from several external factors, including mi-croorganisms that it was not exposed to in utero, the properties related to early stratum corneum barrier function are an important issue of study.
The aims of the present study were to compare TEWL, stratum corneum hydration (SCH), and skin surface pH in different body sites among full-term newborns in the first hours and on the second day of life and adults, and to assess possible correlations among these variables as well as among these vari-ables and infant sex, gestational age, type of delivery, and initial weight loss.
METHODS
The study population consisted of 44 healthy newborn infants, 21 males and 20 females, all appropriate for gestational age of 37 to 42 weeks; 34 were delivered spontaneously and 10 by cesarean section. The research protocol was approved by the Human Re-search Committee of Rabin Medical Center and Israel Ministry of Health. Parental consent was obtained in all cases.
The infants were washed after birth with a wet towel and tap water to eliminate the effect of the lipid biofilm. All had normal Apgar scores and normal rectal temperature, and they were un-dressed for an acclimatization period of 15 minutes. The infants were quiet before the first nursing or at least 2 hours after. None of the infants were receiving medication and none had clinical disturbances.
TEWL, SCH, and skin surface pH were measured on the fore-head, upper back, flexor part of the forearm near the cubital fossa, palms, abdomen, inguinal region, and soles at 5 to 10 hours postpartum and again 24 hours later. All tests were performed in open cribs in a controlled environment, with room temperature from 22°C to 24°C and humidity 50%. During the examination, skin temperature remained stable in all the newborns, as was shown by the Tevameter device (Courage and Khjazaka, Koln, Germany).
TEWL and SCH were measured with a combined Tevameter and Corneometer (Courage and Khjazaka). The Tevameter device consists of a cylindrical probe constructed of 2 hygrosensors and is designed to measure the rate of water evaporation from the surface of the skin. TEWL was computed by averaging the data recorded every 2 seconds for 90 seconds after applying the probe to the skin. The Corneometer measures the electrical capacitance From the Departments of *Dermatology and ‡Neonatology, Rabin Medical
Center, Beilinson Campus, Petah Tiqva, Israel; §Schneider Children’s Med-ical Center of Israel, Petah Tiqva, Israel; and储Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel.
Received for publication Mar 9, 1999; accepted Jan 6, 2000.
Address correspondence to Ayala Maayan-Metzger, MD, Neonatal Inten-sive Care Unit, Schneider Children’s Medical Center of Israel, Petah Tiqva, 49202, Israel. E-mail: maayan@flashmail.com
of the skin surface as an indicator of SCH, which is dependent on the high dielectrical constant of water content relative to other skin components.8Skin pH was measured with a flat glass electrode
pH meter8(Skincheck, Hanna Instruments, El-Hama, Israel).
The same measurements were performed in the same environ-ment at all sites except the inguinal region in a comparison group of 20 healthy adult volunteers with a mean age of 24 years.
Statistical Analysis
Analysis of variance was used to compare differences between newborns and adults and differences among anatomic regions. Nonparametric techniques (Mann-WhitneyUtest and Spearman rank correlation coefficient test) were used for direct numerical comparisons of parameters not known to be distributed normally. APvalue of⬍.05 was considered significant for all tests.
RESULTS TEWL
The comparison between TEWL values in the ne-onates on day 1 and the adults is shown in Fig 1. TEWL was significantly lower in the neonates in the forehead (P⬍.001), palms (P⬍.001), and soles (P⬍
.001), and higher in the forearm (P⬍.0001), with no differences in the abdomen and back. The differences in TEWL values in the neonates between days 1 and 2 are shown in Fig 2. TEWL was significantly higher in the soles (P⬍.01), palms, and forearms (P⬍.001); there was no significant difference in the forehead, back, abdomen, and inguinal region. Regarding re-gional differences, the forearm, palms, and inguinal region showed significantly higher TEWL values than did the other sites examined (P ⬍.05; Fig 2).
SCH
Figure 3 shows the capacitance values on day 1 in the neonates, compared with the adults. SCH was significantly lower in the neonates on the forehead (P⬍.01), back, and abdomen (P⬍.05), and signifi-cantly higher on the forearms (P⬍ .001) and palms (P ⬍ .01). On comparison of the neonatal values between days 1 and 2 (Fig 4), we found that SCH was significantly higher on day 1 in the forearms (P ⬍
.05) and palms (P⬍.005), and significantly lower in the inguinal region (P ⬍ .05). The forearms and palms showed significantly higher values than did the other regions examined (P⬍ .05; Fig 4).
Skin Surface pH
Skin surface pH was significantly higher in the neonates than in the adults in all body sites (P⬍.01; Fig 5), with a mean of 7.08 ⫾ .17 (range: 6.6 –7.5), versus 5.7 ⫾ .16 (range: 4.5– 6.7), respectively. The pH values were significantly lower on day 2 in all body sites, compared with day 1 (P⬍.05; Fig 6), but they were still significantly higher than in the adults. No regional differences were noted in skin surface pH.
Fig 1. TEWL in infants and adults at different anatomic sites (mean ⫾ standard deviation). Differences between the groups were statistically significant for palms and soles and forehead and forearm (P⬍.001).
Fig 2. Differences in TEWL between days 1 and 2 of life at dif-ferent anatomic locations. Differences were statistically significant for palms and forearms (P⬍.001) and soles (P⬍.01). Forearm, palms, and inguinal region had significantly higher TEWL values than did all other examined sites (P⬍.05).
Fig 3. SCH as evaluated by capacitance in infants and adults at different anatomic sites. Differences between the groups were statistically significant for forehead (P⬍.01), back, and abdomen (P⬍.05), and for the forearms (P⬍.001) and palms (P⬍.01).
Fig 4. Differences in SCH between days 1 and 2 of life at different anatomic locations. Statistically significantly lower values were seen on day 2 for the forearms (P⬍.05) and palms (P⬍.005), and significantly higher values for the inguinal region (P⬍.05).
Correlations
SCH correlated with the TEWL in the newborns (P⬍.01) but not in the adults. None of the variables were found to be related to gestational age, sex, mode of delivery (spontaneous versus cesarean), or body weight. There was no correlation between the loss in weight between the first and second days of life and the difference in TEWL.
DISCUSSION
Ultrastructural studies have shown that the epi-dermis of full-term infants is morphologically indis-tinguishable from that of adults,9and it is reasonable
to assume that the biophysical properties are similar as well.10The present study yielded 3 important
find-ings: in the first 2 days of life, most anatomic sites show significant changes in the variables related to stratum corneum function; there are significant dif-ferences between the barrier variables of neonate and adult skin; and there are definitely regional differ-ences in these variables in neonate skin. The finding that the TEWL value in newborns was lower than in adults in most of the anatomic sites indicates that infants have an effective barrier function against wa-ter, in agreement with other studies.1,2,11 Rutter and
Hull1 also observed that the TEWL was relatively
high in the first 4 hours of life and subsequently decreased, suggesting that the surface of the skin was drying out.1 It is of interest that these results are
similar to those reported in elderly individuals, who
have a lower TEWL than do young adults.5 The
reduction of TEWL may reflect an adaptation to ex-trauterine life in the neonates and epidermal atro-phy, resulting in a smaller water reservoir in the aged. Sweating was not a factor in our study, because baseline TEWL readings should not be influenced by sweating at temperatures between 22°C and 24°C and sufficient acclimatization.3Another possible
ex-planation for the low TEWL in newborns is the effect of the vernix caseosa. Although much of the vernix was removed immediately after birth in our series, there may be exogenous lipids that cause surface hydrophobicity without abnormal patterns of des-quamation. There may also be a difference in com-position of skin surface lipids in newborns.12
Neo-nate skin has been reported to have lower levels of enzyme activity than adult skin, and adult levels are not reached until 6 to 12 months of age.13 The skin
lipid profile of 5-day-old infants after daily washing was reported to be similar to that of adult skin.12
The SCH was significantly lower in the newborns than in the adults, providing support for the clinical observation that newborns have dry skin.14 The
TEWL and hydration in the forearm, near the cubital fossa, were exceptionally higher. A possible explana-tion for these findings is the predominant flexion pronation of the forearm in infants in the first days of life. Indeed, the high values may explain why atopic dermatitis does not appear in this classical flexural site in neonates. Further studies should test these variables during early childhood at different flexural sites.
Our study clearly demonstrates significant re-gional differences in TEWL and SCH. This is in con-trast to the study of Orsmark et al,4 who found no
difference in the TEWL in the abdomen, buttocks, and forearm of newborns. However, other studies2,11
support our results, showing higher values of TEWL in the palms and soles. These differences were attrib-uted to background emotional sweating at these sites, but this cannot explain the high TEWL in the forearms found in our study.
The positive relationship between SCH, as re-flected by the capacitance measurements, and TEWL in newborns indicates that the electrical properties of newborn skin may provide an indirect measurement of TEWL; this has also been suggested by Saijo and Tagami,14 Muramatsu et al,15 and Okah et al.16 The
question remains as to why this correlation exists in the skin of full-term infants but not in adult skin.
Our study shows that skin surface pH values in newborns are significantly higher in all body sites than those in adult skin. This corresponds with the findings reported by others.7,17Using the colorimetric
method, Behrendt and Green7 tested skin pH at 3
sites immediately after birth in full-term infants and noted a pH⬎6 in nearly all readings; on the second day of life, more than one half of the recorded values were⬍6; and on the third and fourth days, there was
Fig 5. Skin surface pH in infants and adults at different anatomic sites. Differences between the groups were statistically significant for all body sites (P⬍.01). No regional differences in skin surface pH were noted.
a further trend toward acidity, with stabilization at values similar to those in adults within the first month of life. The high skin pH may be caused by differences in the chemical composition of the skin surface lipids and enzymatic activity.17In view of the
high skin pH in healthy newborns, we recommend that they not be exposed to alkaline soaps and de-tergents, which may inhibit the stabilization process and irritate the physiologic protective acid mantle.
The skin of newborns is known to be relatively susceptible to irritants. This cannot be attributed to a reduced skin barrier function, which has been found by all studies to be effective based on TEWL. The findings in our study suggest that although TEWL is relatively low in most body sites, other variables related to stratum corneum function, such as skin pH and SCH, may enhance the irritant potential of com-pounds on newborn skin.
CONCLUSION
Changes take place in SCH, water loss, and pH in the first 2 days after birth, indicating that the stratum corneum barrier is still in the process of adapting to extrauterine life. There is a significant anatomic vari-ability in TEWL and SCH, and this should be taken into account during evaluations of the permeation of skin care products and topical medications in new-borns.
ACKNOWLEDGMENTS
This study was supported by the Hia Sylvia and Citrinik Fund of Tel Aviv University, and by the Rabin Medical Center Fund for Young Investigators.
We thank Gloria Ginzach and Marian Propp for their editorial and secretarial assistance.
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TREATMENT FOR POLIO [1916]
At the present time we have only an imperfect idea as to what proportion of persons affected with the disease become paralyzed even if no treatment is insti-tuted. Nevertheless, there is apparently general agreement among those who have used immune serum as to its harmlessness, and as to the fact that in certain, possibly in numerous instances its administration is beneficial.
Gould T.A Summer Plague.New Haven, CT: Yale University Press; 1995
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DOI: 10.1542/peds.106.1.105
2000;106;105
Pediatrics
Gil Yosipovitch, Ayala Maayan-Metzger, Paul Merlob and Lea Sirota
Skin Barrier Properties in Different Body Areas in Neonates
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DOI: 10.1542/peds.106.1.105
2000;106;105
Pediatrics
Gil Yosipovitch, Ayala Maayan-Metzger, Paul Merlob and Lea Sirota
Skin Barrier Properties in Different Body Areas in Neonates
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