Relationship of salivary and plasma cortisol levels in preterm infants: results of a prospective observational study and systematic review of the literature

Salivary Cortisol Levels and Clinical Signs of Stress in Premature Neonates Treated with Vimala Massage: A Randomized Controlled Trial

Background: In neonatal intensive care units across the world, premature neonates are exposed to a very stressful environment with high levels of noise, bright lights, pain, infections, invasive procedures, and a lack of maternal contact. Stress is manifested by increased cortisol levels and clinical signs of stress. Objective: To assess the impact of Vimala massage on (1) salivary cortisol levels (primary outcome) and (2) clinical signs of stress (secondary outcomes) in premature neonates. Methods: Neonates (28-36 weeks gestational age) admitted to a nursery unit were randomized one-to-one to receive 15-20 min of Vimala massage administered by their parents twice daily and usual care, or to usual care alone. Salivary cortisol levels were measured by enzyme-linked immunosorbent assay (ELISA) on days 1 and 5. Heart rate, respiratory rate, caloric intake, weight gain, and growth were recorded daily. Groups were compared with t tests, U-tests, and repeated measures analysis of variance. Results: Seventy neonates, 35 in each group, were included. Groups were comparable at baseline. The median decrease in salivary cortisol levels was 0.12 μg/dL in the massage group and 0.07 μg/dL in the control group (p = 0.22). Over 5 days, the massage group had significant decreases in resting heart rate (p = 0.003) and respiratory rate (p = 0.028), and greater weight gains (p = 0.0002), relative to controls. Conclusions: In this randomized trial, adding Vimala massage to usual nursery care was not associated with a significant decrease in salivary cortisol levels in premature neonates, when compared with usual nursery care alone. There were improvements in clinical signs of stress.

Salivary cortisol in healthy dogs: a randomized cross-over study to evaluate different saliva stimulation methods and their effects on saliva volume and cortisol concentration

BACKGROUND

Salivary cortisol collected at home is a useful test to diagnose and monitor Cushing's syndrome in humans. The main problem in dogs is to retrieve a sufficient amount of saliva. The aim of this study was to evaluate different salivary collection methods and compare their effects on volume, pH and cortisol concentration of saliva. Sixteen healthy Beagles were used in a 4 × 4 randomized crossover study with a washout period of 1 week between each of the following collection methods: 1. Salimetrics® cotton swab dipped in ginger powder (ginger group); 2. beef-flavored Salimetrics® (bouillon group); 3. Salivette® cotton swab with an enclosed treat (treat group); 4. plain Salimetrics® (control group). First, baseline saliva (plain cotton swab, S0) and, 2 min later, experimental saliva (according to group allocation above, SExp) were collected. Saliva was gathered by holding the swabs in the animal's mouth for 2 min. After the cross-over study, another saliva sample was collected from all dogs by the ginger method, using a 30 s sampling time (30s-ginger method). Cortisol concentrations were measured by liquid chromatography tandem mass spectrometry.

RESULTS

All three stimulation methods increased saliva production significantly (S0 compared to SExp: ginger p = 0.0005; bouillon p = 0.009; treat p = 0.007). Only ginger stimulation, however, generated a significantly higher amount of saliva (SExp) compared to the control group (p = 0.00001; median (range) amount of saliva for SExp: ginger 1200 ul (600-1700), bouillon 650 ul (200-1900), treat 700 ul (300-1000), control 400 ul (0-1100)). The amount of saliva retrieved by the 30s-ginger method was still higher than that from the control group (p = 0.0004). Bouillon and treat stimulation led to decreased pH values (bouillon, p = 0.0028; treat, 0.0018). Excitement was higher in the ginger group (p = 0.01). Chewing was intensified in the ginger and treat group (ginger, p = 0.003; treat, 0.0009). The cortisol concentration SExp was higher compared to that of S0 in the ginger and treat group (p = 0.02, 0.003). The experimental cortisol concentrations (SExp) were not different between groups.

CONCLUSIONS

The 30s-ginger method could prove useful in evaluating or monitoring dogs with Cushing's syndrome, as sampling at home for 30 s by the owner seems feasible.

Is correlation between plasma and salivary cortisol levels an important indicator of stress?: A meta-analysis study

The purpose of this study was to examine the practical importance of the correlation values between plasma and salivary cortisol levels using meta-analysis study. In this way, researchers focusing on cortisol levels in different individuals can use more systemic, practical and reliable evidence than using just salivary or plasma cortisol levels separately. For this purpose, correlational studies from 2000 up to now were collected and analyzed by meta-analysis. Results based on 18 effect sizes (n = 743) revealed that effect sizes of the correlations between plasma and salivary cortisol levels represented large effects. The overall combined effect size (Hedges's = 1.55) also represented a large effect. This finding indicates the practical importance of the correlation values for stress studies. The use of the correlation values for examining the cortisol levels in stress studies will be discussed in detail.

The Calming Effect of Maternal Breast Milk Odor on Term Infant: A Randomized Controlled Trial

Purpose: This study was carried out to assess the effect of the odor of breast milk and formula milk on reducing the acute pain of newborn infants during the heel-prick blood sampling. Methods: Eighty-four newborn were randomly assigned into two groups (formula milk group and breast milk group) with 42 infant searches. The pain that the newborn felt before, during, and after heel-prick blood sampling was assessed using Neonatal Infant Pain Scale; their heart rate and blood oxygen saturation were measured with a pulse oximeter. Saliva samples were taken from newborns before and after sampling, and their salivary cortisol level was measured. During sampling, the crying duration of newborn was recorded with a chronometer. Results: The pain threshold and heart rates of the newborn in the breast milk group were significantly lower than those in the formula milk group (p < 0.001). Salivary cortisol in the formula milk group increased and oxygen saturation levels in these infants decreased significantly more as compared to the breast milk group (p < 0.05). Conclusions: The odor of breast milk may be helpful in reducing the pain of newborn during heel-prick blood sampling.

Impact of Skin-to-Skin Parent-Infant Care on Preterm Circulatory Physiology

OBJECTIVES

To ascertain the impact of skin-to-skin care between parents and infants on cardiac function and cerebral blood flow in preterm infants.

STUDY DESIGN

We undertook a prospective study of 40 self-ventilating preterm infants at a quaternary center and assessed cardiac performance and cerebral blood flow. Assessments were carried out two hours before skin-to-skin care and then 60 minutes after skin-to-skin care (with the infant still on parent and turned supine).

RESULTS

Infants were 30.5 ± 0.6 weeks' gestational age and 1378 ± 133 g birthweight. Axillary temperature noted a nonsignificant increase during skin-to-skin care from 36.7 ± 0.07°C to 36.9 ± 0.07°C (P = .07). Cardiac contractility (right ventricular fractional area change [26.5% ± 0.3% vs 27.8% ± 0.4; P < .001] and tricuspid annular plane systolic excursion [0.73 ± 0.03 cm vs 0.77 ± 0.03 cm; P = .02]) increased significantly, coincident with decreased measures of pulmonary vascular resistance. An increase in systemic cardiac output was associated with increased cerebral blood flow and reduced middle cerebral artery resistive index (0.81 ± 0.02 vs 0.74 ± 0.02; P = .0001).

CONCLUSIONS

We documented a significant circulatory beneficial adaptation to a common neonatal practice. These findings align with previously documented physiologic benefits in cardiorespiratory stability and cardiac rhythm in preterm infants, and may be mediated through modulation of the autonomic nervous system.

Saliva cortisol, melatonin levels and circadian rhythm alterations in Chinese primary school children with dyslexia

Cortisol is the main end product of hypothalamic-pituitary-adrenal gland (HPA axis), and melatonin (MT) has a regulating effect on HPA axis, and both are closely related to individual behavior and cognitive function. We aimed to evaluate cortisol and MT roles on children dyslexia in this study.A total of 72 dyslexic children and 72 controls were recruited in this study. Saliva samples were collected in the morning, afternoon, and night, respectively. The levels of saliva cortisol and MT were measured by enzyme-linked immunosorbent assay method. Differences of cortisol and MT levels between dyslexic and normal children were compared, and the variation trend was also analyzed by dynamic monitoring in 3 time points.The levels of salivary cortisol and MT in children with dyslexia were all lower than those in normal children whether in the morning (7:30-8:30 AM ), at afternoon (15:30-16:30 PM ) or at night (21:30-22:30 PM ) (all P < .001). Compared with normal children, the circadian rhythm variations of salivary cortisol and MT in dyslexic children disappeared and became disordered. The salivary cortisol and MT levels in children with dyslexia were declined throughout the day; and the circadian rhythm was disordered or disappeared.The results suggest that cortisol and MT levels and their circadian rhythm may affect children dyslexia, but the mechanisms need further exploration.

Saliva for Assessing Vitamin A Status in Extremely Preterm Infants: A Diagnostic Study

BACKGROUND

Salivary measurement of hormones and vitamins is gaining prominence as a minimally invasive procedure with the negligible potential for harm. We aimed to assess the utility of saliva for assessing vitamin A status in extremely preterm infants.

METHODS

Paired saliva and blood samples were collected at 4 weeks of age from infants born <28 weeks of gestation using a proprietary polymer swab. Plasma retinol was measured using high-performance liquid chromatography, and salivary retinol was measured using enzyme-linked immunosorbent assay.

RESULTS

Thirty infants were recruited with a median (IQR) gestation and birth weight of 26.2 weeks (24.8-27.2) and 865 g (718-1,002), respectively. An adequate volume of saliva (>50 µL) was obtained in 68%. There was no significant correlation (Spearman's correlation coefficient = 0.16, p = 0.3) between individual plasma and salivary retinol levels. Bland-Altman analysis showed wide limits of agreement (-113 to +119%) between individual plasma and salivary retinol levels.

CONCLUSION

Individual vitamin A status cannot be determined reliably from saliva in extremely preterm infants using current collection materials and analysis techniques.

Neonatal adrenal insufficiency: Turkish Neonatal and Pediatric Endocrinology and Diabetes Societies consensus report

It is difficult to make a diagnosis of adrenal insufficiency in the newborn, because the clinical findings are not specific and the normal serum cortisol level is far lower compared to children and adults. However, dehydratation, hyperpigmentation, hypoglycemia, hyponatremia, hyperkalemia and metabolic acidosis should suggest the diagnosis of adrenal insufficiency. Hypotension which does not respond to vasopressors should especially be considered a warning. If the adrenocorticotropin hormone level measured simultaneously with a low serum cortisol level is 2-fold higher than the upper normal limit of the reference range, a diagnosis of primary adrenal insufficiency is definite. Even if the serum cortisol level is normal, a diagnosis of relative adrenal insufficiency can be made with clinical findings, if the patient is under heavy stress. The serum cortisol level should be measured using the method of ‘high pressure liquid chromatography’ or ‘LC mass spectrometry’. Adrenal steroid biosynthesis can be evaluated more specifically and sensitively with ‘steroid profiling’. Rennin and aldosterone levels may be measured in addition to serum electrolytes for the diagnosis of mineralocorticoid insufficiency. Adrenocorticotropic hormone stimulation test may be used to confirm the diagnosis and elucidate the etiology. In suspicious cases, treatment can be initiated without waiting for the adrenocorticotropic hormone stimulation test. In schock which does not respond to vasopressors, intravenous hydrocortisone at a dose of 50-100 mg/m² or a glucocorticoid drug at an equivalent dose should be initiated. In maintanence treatment, the physiological secretion rate of hydrocortisone is 6 mg/m²/day (15 mg/m²/day in the newborn). The replacement dose should be adjusted with clinical follow-up and by monitoring growth rate, weight gain and blood pressure. Fludrocortisone (0,1 mg tablet) is given for mineralocorticoid treatment (2x0,5-1 tablets). A higher dose may be needed in the neonatal period and in patients with aldosterone resistance. If hyponatremia persists, oral NACl may be added to treatment. In the long-term follow-up, patients should carry an identification card and the glucocorticoid dose should be increased 3-10-fold in cases of stress.

Novel method of measuring chronic stress for preterm infants: Skin cortisol

BACKGROUND AND OBJECTIVES

Infants who begin life in the medicalized environment of the neonatal intensive care unit (NICU) do so under stressful conditions. Environmental exposures are often abrasive to vulnerable infants, while invasive and noninvasive lifesaving interventions provide additional pain and/or stress. The most commonly selected biomarker to measure stress is cortisol. The skin is the barrier between the external environment and communicates with our neurological, endocrine and immune regulatory networks. To examine if skin cortisol may be a reliable biomarker of stress, NICU stress exposure and repeated measurements of skin cortisol in very preterm infants were examined retrospectively during the first 6 weeks of life. The temporal relationship between skin cortisol and NICU stress exposure was also analyzed.

MATERIALS AND METHODS

Participants included 82 preterm infants born weighing less than 1500 g, admitted to a level III NICU, with a mean gestational age of 28.5 weeks. Infants were studied from birth through 6 weeks of life. NICU stress data was collected using the Neonatal Infant Stressor Scale. Skin samples were collected using d-squame tape as soon after birth as possible and every two weeks thereafter.

RESULTS

On average, infants experienced approximately 43 stressful events per day during the first 6 weeks of life in the NICU. Stress level and cortisol reactivity varied by gestation age. Higher stress resulted in higher cortisol for infant >28 weeks; lower stress scores were associated with higher stress for infants <28 weeks. Stress exposure during 7 days prior to cortisol sampling yielded the highest AUC for the 2 groups. A statistically significant interaction was identified between gestational age and stress exposure during the previous 7 days (p < 0.01).

CONCLUSION

This is the first study to demonstrate skin cortisol as a preterm infant biomarker of chronic stress exposure. For infants with appropriate skin maturation, this non-invasive sampling method provides several benefits. Importantly, this method may be less intrusive and disruptive for preterm infants.

The effect of nesting positions on pain, stress and comfort during heel lance in premature infants

BACKGROUND

Nesting positions are commonly used in procedural analgesic administration in premature neonates. The effectiveness of nesting positions is questioned. The aim of the this study was to assess the pain, stress, comfort and salivary cortisol and melatonin values in nesting positions during the heel lance procedure in premature infants at the NICU.

METHODS

Experimental research; repeated measurement design. The sample comprised 33 premature neonates with gestational age of 31-35 weeks who had been hospitalized in the NICU. Nesting positions were given using linen or towels. The procedure of heel lance was recorded on camera. The camera recordings were evaluated according to the NIPS and the COMFORTneo scale. Saliva samples were obtained five minutes prior to and 30 min after the heel lance procedure. Salivary Cortisol and Melatonin were measured using the Salimetrics Cortisol Elisa Kit and the Salimetrics Melatonin Elisa Kit.

RESULTS

The crying time, the mean NIPS score, the COMFORTneo score, the COMFORTneo NRS-pain scores and the COMFORTneo NRS-distress scores for premature neonates who were in the prone position during the procedure were significantly lower than the scores in the supine position (p < 0.000). Furthermore, the level of salivary cortisol five minutes prior to and 30 min after the heel lance procedure had significantly decreased in the prone position; however, there were insignificant differences in the mean levels of salivary melatonin between the positions.

CONCLUSIONS

Nesting in the prone position has a pain reducing effect, enhancing comfort and reducing stress in premature infants.

MECHANISMS IN ENDOCRINOLOGY: A sense of time of the glucocorticoid circadian clock: from the ontogeny to the diagnosis of Cushing's syndrome

The circadian rhythm of glucocorticoids has long been recognised within the last 75 years. Since the beginning, researchers have sought to identify basic mechanisms underlying the origin and emergence of the corticosteroid circadian rhythmicity among mammals. Accordingly, Young, Hall and Rosbash, laureates of the 2017 Nobel Prize in Physiology or Medicine, as well as Takahashi's group among others, have characterised the molecular cogwheels of the circadian system, describing interlocking transcription/translation feedback loops essential for normal circadian rhythms. Plasma glucocorticoid circadian variation depends on the expression of intrinsic clock genes within the anatomic components of the hypothalamic-pituitary-adrenal axis, which are organised in a hierarchical manner. This review presents a general overview of the glucocorticoid circadian clock mechanisms, highlighting the ontogeny of the pituitary-adrenal axis diurnal rhythmicity as well as the involvement of circadian rhythm abnormalities in the physiopathology and diagnosis of Cushing's disease.

Associations Between Hormonal Biomarkers and Cognitive, Motor, and Language Developmental Status in Very Low Birth Weight Infants

BACKGROUND

Male infants are more prone to health problems and developmental delays than female infants.

OBJECTIVES

On the basis of theories of gender differences in brain development and social relationships, we explored associations between testosterone and cortisol levels with infant cognitive, motor, and language development ("infant development") in very low birth weight (VLBW) infants, controlling for mother-infant interactions, characteristics of mothers and infants, and days of saliva collection after birth.

METHODS

A total of 62 mother-VLBW infant pairs were recruited from the newborn intensive care unit of a tertiary medical center in the Southeast United States. Data were collected through infant medical record review, biochemical measurement, observation of mother-infant interactions, and standard questionnaires. Infant development was assessed at 6 months corrected age (CA), and mother-infant interactions were observed at 3 and 6 months CA.

RESULTS

General linear regression with separate analyses for each infant gender showed that high testosterone levels were positively associated with language development of male infants after controlling for mother-infant interactions and other covariates, whereas high cortisol levels were negatively associated with motor development of female infants after controlling for mother-infant interactions.

CONCLUSIONS

Steroid hormonal levels may well be more fundamental factors for assessing infant development than infant gender or mother-infant interactions at 6 months CA.

Short-Term Effects of Hydrokinesiotherapy in Hospitalized Preterm Newborns

Background. In the neonatal intensive care unit (NICU) environment, preterm newborns are subject to environmental stress and numerous painful interventions. It is known that hydrokinesiotherapy promotes comfort and reduces stress because of the physiological properties of water. Objective. To evaluate the short-term effects of hydrokinesiotherapy on reducing stress in preterm newborns admitted to the NICU. Materials and Methods. Fifteen preterm newborns underwent salivary cortisol measurement, pain evaluation using the Neonatal Infant Pain Scale (NIPS), and heart rate, respiratory rate, and peripheral oxygen saturation measurements before and after the application of hydrokinesiotherapy. Results. The mean gestational age of the newborns was 34.2 ± 1.66 weeks, and the mean weight was 1823.3 ± 437.4 g. Immediately after application of hydrokinesiotherapy, a significant reduction was observed in salivary cortisol (p = 0.004), heart rate (p = 0.003), and respiratory rate (p = 0.004) and a significant increase was observed in peripheral oxygen saturation (p = 0.002). However, no significant difference was observed in the NIPS score (p > 0.05). Conclusion. In the present study, neonatal hydrotherapy promoted short-term relief from feelings of stress. Neonatal hydrokinesiotherapy may be a therapeutic alternative. However, this therapy needs to be studied in randomized, crossover, and blinded trials. This trial is registered with NCT02707731.

Kangaroo care by fathers and mothers: comparison of physiological and stress responses in preterm infants

OBJECTIVE

To compare physiological and biochemical responses in stable preterm neonates and their parents following kangaroo mother care (KMC) and kangaroo father care (KFC).

STUDY DESIGN

We conducted a prospective cross-over design study of stable preterm neonates of <35 weeks gestation in a tertiary Neonatal Unit in Toronto. All neonates received KMC and KFC for 1 h on consecutive days in a random order. Heart rate, temperature, blood pressure, oxygen saturation and salivary cortisol in infants before and after kangaroo care and heart rate, temperature and salivary cortisol in parents before and after kangaroo care were measured. Pairwise comparisons of changes in these measures were analyzed.

RESULT

Twenty-six sets of neonates and their parents were studied for physiological parameters, of which 19 had adequate samples for salivary cortisol assessment. The infants had a mean birth weight of 1096 g (s.d.=217) and a mean postmenstrual age at study of 32 weeks (s.d.=2). There were no significant differences in the changes in mean heart rate (P=0.51), temperature (P=0.37), oxygen saturation (P=0.50), systolic blood pressure (P=0.32), mean blood pressure (0.10) and salivary cortisol (P=0.50) before and after KMC or KFC in the neonates. The changes in mean heart rate (P=0.62), temperature (P=0.28) and salivary cortisol (P=0.59) before and after kangaroo care were similar between mothers and fathers.

CONCLUSION

No significant differences in physiological and stress responses were identified following KMC or KFC in preterm neonates. KFC may be as safe and as effective as KMC.

Influence of light exposure at nighttime on sleep development and body growth of preterm infants

Previous studies have demonstrated that a light-dark cycle has promoted better sleep development and weight gain in preterm infants than constant light or constant darkness. However, it was unknown whether brief light exposure at night for medical treatment and nursing care would compromise the benefits brought about by such a light-dark cycle. To examine such possibility, we developed a special red LED light with a wavelength of >675 nm which preterm infants cannot perceive. Preterm infants born at <36 weeks’ gestational age were randomly assigned for periodic exposure to either white or red LED light at night in a light-dark cycle after transfer from the Neonatal Intensive Care Unit to the Growing Care Unit, used for supporting infants as they mature. Activity, nighttime crying and body weight were continuously monitored from enrolment until discharge. No significant difference in rest-activity patterns, nighttime crying, or weight gain was observed between control and experimental groups. The data indicate that nursing care conducted at 3 to 4-hour intervals exposing infants to light for <15 minutes does not prevent the infants from developing circadian rest-activity patterns, or proper body growth as long as the infants are exposed to regular light-dark cycles.