Norepinephrine Excretion Rates Research Articles

Decreased urinary excretion of norepinephrine and dopamine in autonomic synucleinopathies.

Autonomic synucleinopathies feature autonomic failure and intracellular deposition of the protein alpha-synuclein. Three such conditions are the Lewy body diseases (LBDs) Parkinson's disease (PD) and pure autonomic failure (PAF) and the non-LBD synucleinopathy multiple system atrophy (MSA). These diseases all entail catecholaminergic abnormalities in the brain, sympathetically innervated organs, or both; however, little is known about renal catecholaminergic functions in autonomic synucleinopathies. We measured urinary excretion rates of the sympathetic neurotransmitter norepinephrine, the hormone epinephrine, the autocrine-paracrine substance dopamine, the catecholamine precursor 3,4-dihydroxyphenylalanine (DOPA), 3,4-dihydroxyphenylglycol (DHPG, the main neuronal metabolite of norepinephrine), and 3,4-dihydroxyphenylacetic acid (DOPAC, a major dopamine metabolite), in PD, PAF, and MSA groups and controls. Data were reviewed from all research participants who had urine collections (usually 3.5 h) at the National Institutes of Health (NIH) Clinical Center from 1995 to 2024. The control cohort had neither autonomic failure nor a movement disorder. Norepinephrine excretion rates were decreased compared with controls in PD (p = 0.0001), PAF (p < 0.0001), and MSA (p < 0.0001). Dopamine excretion was also decreased in the three groups (PD: p = 0.0136, PAF: p = 0.0027, MSA: p = 0.0344). DHPG excretion was decreased in PD (p = 0.0004) and PAF (p = 0.0004) but not in MSA. DOPA and epinephrine excretion did not differ among the study groups. Autonomic synucleinopathies involve decreased urinary excretion rates of norepinephrine and dopamine. Since virtually all ofurinary dopamine in humans is derived from circulating DOPA, the low rates of urinary norepinephrine and dopamine excretion may reflect dysfunctions in the renal sympathetic noradrenergic system, the DOPA-dopamine autocrine-paracrine system, or both systems.

Urinary Norepinephrine Is a Metabolic Determinant of 24-Hour Energy Expenditure and Sleeping Metabolic Rate in Adult Humans.

Interindividual variability in 24-hour energy expenditure (24EE) during energy-balance conditions is mainly determined by differences in body composition and demographic factors. Previous studies suggested that 24EE might also be influenced by sympathetic nervous system activity via catecholamine (norepinephrine, epinephrine) secretion. Therefore, we analyzed the association between catecholamines and energy expenditure in 202 individuals from a heterogeneous population of mixed ethnicities. Participants (n = 202, 33% female, 14% black, 32% white, 41% Native American, 11% Hispanic, age: 36.9 ± 10.3 y [mean ± SD], percentage body fat: 30.3 ± 9.4) resided in a whole-room calorimeter over 24 hours during carefully controlled energy-balance conditions to measure 24EE and its components: sleeping metabolic rate (SMR), awake-fed thermogenesis (AFT), and spontaneous physical activity (SPA). Urine samples were collected, and 24-h urinary epinephrine and norepinephrine excretion rates were assessed by high-performance liquid chromatography. Both catecholamines were associated with 24EE and SMR (norepinephrine: +27 and +19 kcal/d per 10 μg/24h; epinephrine: +18 and +10 kcal/d per 1 μg/24h) in separate analyses after adjustment for age, sex, ethnicity, fat mass, fat-free mass, calorimeter room, temperature, and physical activity. In a multivariate model including both norepinephrine and epinephrine, only norepinephrine was independently associated with both 24EE and SMR (both P < .008), whereas epinephrine became insignificant. Neither epinephrine nor norepinephrine were associated with adjusted AFT (both P = .37) but epinephrine was associated with adjusted SPA (+0.5% per 1 μg/24h). Our data provide compelling evidence that sympathetic nervous system activity, mediated via norepinephrine, is a determinant of human energy expenditure during nonstressed, eucaloric conditions.

The effects of age and ethnicity on the circadian variation of catecholamines and cortisol in employed women

BackgroundWomen employed outside the home in urban settings must adapt to changing circadian microenvironments. The pattern and extent of vasoactive hormone responses to these changes may depend upon age and ethnic background. The purpose of this study was to evaluate the effects of age and ethnicity on the circadian variation of urinary norepinephrine, epinephrine, and cortisol excretion across work, home and sleep microenvironments.MethodsThe subjects of the study were 95 women (38 European-American, age = 35.4 ± 7.4; 28 African-American, age = 33.4 ± 7.9; 12 Asian-American, age = 36.7 ± 9.3 and 17 Hispanic-American age = 31.6 ± 10.9) employed as secretaries, lab technicians or office supervisors in New York City. Variation in the hormones across the microenvironments was evaluated using repeated measures ANCOVA with age group (18–29.9; 30–39.9; 40–49.9) and ethnicity as fixed factors.ResultsThe results show that for norepinephrine and epinephrine, work excretion rates are substantially higher than sleep rates (p < .001), and for epinephrine home rates were higher than sleep rates (p < .001). Work and sleep cortisol excretion rates were also significantly higher than the rate at home, consistent with cortisol’s circadian rhythm. (p < .002). Women in their twenties had substantially lower norepinephrine excretion rates than women over 30 (p < .04). There were also ethnic differences in norepinephrine (p < .04) and epinephrine (p = .11) output with Asian-American women having the lowest and African-American women having the highest rates. This variation is likely related to the ethnic variation in weight. There was no significant variation in cortisol excretion with age or ethnicity.ConclusionThe circadian rates of norepinephrine excretion differ by age and that of both catecholamines differ by ethnicity among women working outside the home. It is speculated that the age variation in norepinephrine may contribute to the development of vasomotor symptoms.

Diurnal variations of heart rate, urine flow and catecholamine excretion in subjects wearing clothing that provides different thermal insulation

This study investigated the effects of clothing providing different Clo values upon the circadian rhythm of sympathetic nervous activity, as inferred from urinary catecholamine excretion and heart rate, in a thermoneutral environment. Seven health female subjects were studied for 37.5 h, from 21:00 h on the first day to 10:30 h on the third day, in an isolated climatic chamber controlled at 23.8 ± 0.2 °C and 60 ± 5% RH. Light intensity was 500 lux from 06:30 to 19:30 h, 100 lux from 19:30 to 22:30 h and 0 lux from 22:30 to 06:30 h. Subjects were tested while wearing two different types of clothing: Type L, offering 1.048 Clo of thermal insulation and with the subjects’ extremities covered; and Type H, 0.744 Clo of thermal insulation and the subjects’ extremities exposed. Urine samples were collected every 4 h, their volumes were measured and they were later assayed for their contents of adrenaline and noradrenaline; the mean heart rate for each of these 4-h periods was also calculated. The daily profiles of the variables were assessed by ANOVA, which indicated that the amplitudes and phases of the daily rhythms differed between the clothing types. This result was examined in more detail by assessing the profiles by single and group cosinor analysis (period = 24 h). All four physiological variables showed clear and statistically significant group cosinor rhythms with both types of clothing. The mean amplitudes of urine flow, the excretion rate of urinary adrenaline and heart rate were greater when wearing Type H rather than Type L clothing (p = 0.01 for urine flow and heart rate; p = 0.072 for rate of excretion of adrenaline). Also, the acrophase of the rate of urinary adrenaline excretion was earlier in all subjects wearing Type H rather than Type L clothing (p = 0.048), and the acrophases of urine flow and urinary noradrenaline excretion rate were earlier in six and five of the subjects, respectively. These results show that clothing which is worn in an environment of moderate temperature (23.8 °C) and which offers a lower Clo value (especially if the distal extremities are exposed) might induce an increase in amplitude and/or an advance of acrophase in circadian rhythms of urine flow, excretion of urinary catecholamines and heart rate. It is suggested that these rhythmic changes, which imply changes in the daily profile of sympathetic nervous system activity, might be important when daily thermoregulation and comfort in response to the type of clothing being worn in daily life are considered.

Circadian misalignment increases cardiovascular disease risk factors in humans

Shift work is a risk factor for hypertension, inflammation, and cardiovascular disease. This increased risk cannot be fully explained by classic risk factors. One of the key features of shift workers is that their behavioral and environmental cycles are typically misaligned relative to their endogenous circadian system. However, there is little information on the impact of acute circadian misalignment on cardiovascular disease risk in humans. Here we show-by using two 8-d laboratory protocols-that short-term circadian misalignment (12-h inverted behavioral and environmental cycles for three days) adversely affects cardiovascular risk factors in healthy adults. Circadian misalignment increased 24-h systolic blood pressure (SBP) and diastolic blood pressure (DBP) by 3.0 mmHg and 1.5 mmHg, respectively. These results were primarily explained by an increase in blood pressure during sleep opportunities (SBP, +5.6 mmHg; DBP, +1.9 mmHg) and, to a lesser extent, by raised blood pressure during wake periods (SBP, +1.6 mmHg; DBP, +1.4 mmHg). Circadian misalignment decreased wake cardiac vagal modulation by 8-15%, as determined by heart rate variability analysis, and decreased 24-h urinary epinephrine excretion rate by 7%, without a significant effect on 24-h urinary norepinephrine excretion rate. Circadian misalignment increased 24-h serum interleukin-6, C-reactive protein, resistin, and tumor necrosis factor-α levels by 3-29%. We demonstrate that circadian misalignment per se increases blood pressure and inflammatory markers. Our findings may help explain why shift work increases hypertension, inflammation, and cardiovascular disease risk.

Combined food intake and exercise unmask different hormonal responses in lean and obese children

Our purpose was to investigate the effect of obesity in prepubertal children on the hormonal response to exercise performed under different conditions of nutrient availability. Prepubertal obese (age, 10.3 ± 1.8 years; %body fat, 36.1 ± 6.1; n = 9) and lean (age, 9.2 ± 1.6 years; %body fat, 22.2 ± 4.1; n = 7) children completed 2 experimental sessions in which they performed a 30 min of cycling exercise at 50% of their maximal aerobic power either 1 h (T1h) or 3 h (T3h) after a standardized breakfast. Plasma insulin-like growth factor 1 (IGF-1), IGF binding protein 1 (IGFBP-1), and IGFBP-3 levels were assessed at baseline and after exercise. Urine was collected during the sessions, and catecholamine and glucocorticoid excretions were analyzed. A significant time effect was observed for IGFBP-1; postexercise levels decreased in lean and obese children (p ≤ 0.001). IGF-1 and IGFBP-3 were not affected by obesity or food intake combined with exercise. In lean children, urinary excretion rates of epinephrine, norepinephrine, cortisol, and cortisone were significantly higher during the sessions than during the overnight resting period; in obese children, only epinephrine in T1h was significantly increased (p ≤ 0.05 for all). Our study indicates that the activity of the hypothalamic-pituitary-adrenal axis and sympathetic adrenal medullary axis was similar in lean and obese children, based on measurement under resting conditions, but response to exercise performed in postprandial conditions was altered in obese children for both axes. In addition, exercise in the postprandial state elicited a decrease in IGFBP-1 plasma levels, whereas IGF-1 and IGFBP-3 levels were not significantly altered.

Urinary norepinephrine and epinephrine excretion rates are heritable, but not associated with office and ambulatory blood pressure

Genetic and environmental contributions to urinary excretion rates of norepinephrine (U(NE)V) and epinephrine (U(E)V) and their association with blood pressure (BP) were investigated in 91 African American (mean age, 17.3±2.6 years) and 101 European American (mean age, 18.7±3.4 years) mono- and di-zygotic twins. Genetic modeling was performed using Mx software. U(NE)V (1.9±1.3 μg h(-1)) and U(E)V (0.2±0.2 μg h(-1)) were highly correlated (r=0.81, P<0.001). Significant heritabilities for U(NE)V (0.68) and U(E)V (0.74) without ethnic and gender effects were observed. The genetic correlation between U(NE)V and U(E)V was 0.86. There was no clear pattern of correlations for U(NE)V and U(E)V with BP measures in European Americans, but African Americans showed some inverse correlations of moderate size. Measurements of U(NE)V and U(E)V provide a viable method for the study of sympathetic tone and are substantially heritable.

Urinary 5-HIAA Excretion is not Increased in Patients with Head and Neck Paragangliomas

Case reports have documented carcinoid-like features in head and neck paragangliomas (HNPGLs), which, in addition to catecholamine storing granules, may also contain granules with serotonin. Serotonin is metabolized to 5-hydroxyindoleacetic acid (5-HIAA). To assess the urinary excretion rates of 5-HIAA and catecholamines in HNPGL patients. In 114 consecutive HNPGL patients, normetanephrine, metanephrine, norepinephrine, epinephrine, VMA, dopamine, 3-methoxytyramine and 5-HIAA excretion rates were measured in two 24-hour urinary samples. Increased excretion rates were defined as an increase of the average hormone excretion rate of 2 urine samples above the reference range. In all patients with catecholamine excess, intrathoracic and abdominal paragangliomas were excluded by 123I-MIBG scintigraphy, MRI and/or CT. Genetic screening for mutations in genes of the succinate dehydrogenase (SDH) family was performed. Mean urinary 5-HIAA excretion rate was 14±9 μmol/24 hours (reference range 10-44 μmol/24 hours). Urinary 5-HIAA excretion was slightly increased in only 1 patient (48 μmol/24 hours). None of the 50 patients (44%) with increased urinary excretion rates of catecholamines and/or their metabolites had elevated 5-HIAA excretion. Urinary 5-HIAA excretion is within the normal reference range in almost all HNPGL patients. Therefore, this parameter has no clinical relevance in the routine clinical assessment of HNPGL patients.

Plasma chromogranin A levels are increased in a small portion of patients with hereditary head and neck paragangliomas

The majority of patients with head and neck paragangliomas (HNPGL) have biochemically silent tumours. Chromogranin A (CgA) is a tumour marker for neuroendocrine tumours. To assess the role of CgA as a tumour marker in patients with hereditary HNPGL. We included 95 consecutive patients with hereditary HNPGL for screening of plasma CgA levels and catecholamine excess by measurement of 24-h urinary excretion of (nor)metanephrine, (nor)adrenaline, VMA, dopamine and 3-methoxytyramine. In all patients with catecholamine excess, abdominal/intrathoracic paragangliomas were excluded by (123) I-MIBG scintigraphy, MRI and/or CT. Plasma CgA levels were increased in only 15 of 95 patients (16%). Thirty-three of the 95 patients (35%) had increased urinary excretion rates of catecholamines. Six of these 33 patients (18%) had increased plasma CgA levels. Nine of the 62 patients (15%) with a biochemically silent tumour, i.e. no increased urinary excretion of catecholamines or their metabolites, had increased CgA levels. Increased plasma CgA levels were positively correlated with urinary excretion rates of noradrenaline (r = 0·68, P = 0·005) and normetanephrine (r = 0·68, P = 0·005). There was a positive correlation between maximal HNPGL diameter and plasma CgA levels in the 57 patients with a single HNPGL (r = 0·57, P = 0·001). Plasma CgA levels are increased in only a small portion of patients with hereditary HNPGL and have limited additional value to the combination of radiological and routine biochemical assessment of patients with HNPGL. Increased plasma CgA levels are associated with increased noradrenergic activity and tumour size in patients with a single HNPGL.

Ecological and sociodemographic effects on urinary catecholamine excretion in adult Samoans

Background: Ecological and sociodemographic correlates of stress may contribute to cardiovascular disease risk in modernizing Samoans.Aim: The effects of peri-urban vs rural residence, education, occupation, caffeine intake and cigarette consumption on urinary catecholamine excretion were studied in Samoan adults.Subjects and methods: Five hundred and seven participants, aged 29–69 years, were randomly selected from nine villages throughout Samoa. Sociodemographic and lifestyle factors were assessed by questionnaire. Epinephrine and norepinephrine excretion rates were measured by high performance liquid chromatography with electrochemical detection in overnight urine samples. Age ( ≤ 40 vs >40 years) and gender-specific regression models were estimated to detect associations with BMI-adjusted catecholamine excretion.Results: Norepinephrine was significantly higher in peri-urban young men and older women. Epinephrine was significantly higher in peri-urban older men. Adjustment for caffeine attenuated the relationship between residence and norepinephrine in young women.Conclusion: General residential exposure to modernization in urban villages is a significant correlate of increased overnight catecholamine excretion rates and is consistent with past studies. Caffeine consumption in younger women plays a complex role in stress-related catecholamine excretion. Further studies of individual level attitudinal and behavioural factors in Samoans are needed to understand psychosocial stress, physiologic arousal and health.

Workplace observation of work stressors, catecholamines and musculoskeletal pain among male employees

Prolonged activation of the sympathetic-adrenal medullary system during work and the lack of recovery after work may indicate a risk for musculoskeletal pain (ie, neck, shoulder, or low-back pain). This field study tested whether a high level of work stressors are associated with musculoskeletal pain and higher urinary norepinephrine excretion rates at work, after work, and on Sundays. Altogether 32 male employees working in adult education took part in a three-phase repeated-measures field study including workplace observation, self-report of musculoskeletal pain, and measurement of urinary catecholamine at work, in the evening after work, and at corresponding times on Sundays. In univariate analyses, work stressors and workday levels of norepinephrine were significantly higher in the participants with high levels of musculoskeletal pain. Moreover, regressing workday norepinephrine excretion rates on predictor variables in the multilevel regression analysis showed a significant interaction between work stressors and musculoskeletal pain (P=0.011) with elevated excretion rates of norepinephrine in those exposed to a high level of work stressors and, at the same time, reporting higher levels of musculoskeletal pain. High work stressors turned out to be associated with musculoskeletal pain and norepinephrine concentration in male employees. Increased activity of the sympathetic-adrenal medullary system seems to play an important role in work-related musculoskeletal pain.

Influence of α-adrenergic blockade on the catecholamine response to exercise at 4,300 meters

This investigation examined the influence of alpha-adrenergic blockade on plasma and urinary catecholamine responses to both exercise and high-altitude exposure. Sixteen nonsmoking, eumenorrheic women (age 23.2 +/- 1.4 years, 68.7 +/- 1.0 kg) were studied at sea level and during 12 days of high-altitude exposure (4,300 m). Subjects received either alpha-blockade (prazosin 3 mg/d) or a placebo in a double-blinded, randomized fashion. Resting plasma and 24-hour urine samples were collected periodically throughout the duration of the study. Further, subjects participated in submaximal exercise tests (50 minutes at 50% sea level maximum oxygen consumption [Vo2max]) at Sea level and on days 1 and 12 at altitude. Urinary norepinephrine (NE) excretion rates increased significantly over time at altitude, with blocked subjects having greater values compared to controls. Plasma NE levels increased significantly with chronic altitude exposure compared to sea level and acute hypoxia both at rest and during exercise. NE levels at rest were greater for blocked compared to control subjects during all conditions. Urinary and plasma epinephrine (EPI) levels increased dramatically, with acute altitude exposure returning to sea level values by day 12 of altitude exposure. EPI levels were greater for blocked compared to placebo both at rest and during exercise for all conditions studied. Changes in alpha-adrenergic activity over time at altitude were associated with select metabolic and physiologic adjustments. The presence of alpha-blockade significantly affected these responses during chronic altitude exposure. It was concluded that: (1) alpha-adrenergic blockade elicited a potentiated sympathoadrenal response to the stress of both exercise as well as high-altitude exposure, and (2) the sympathetics, via alpha-adrenergic stimulation, contribute to a number of key adaptations associated with acclimatization to high altitude.

Urinary catecholamine levels in daily life are elevated in women at familial risk of breast cancer

Recent experimental research has shown that women facing the chronic stress of being at familial risk of breast cancer have greater neuroendocrine reactivity responses to stressful laboratory tasks. Whether this enhanced stress response also occurs outside the laboratory under daily life conditions is unknown. In the present study, urinary epinephrine and norepinephrine excretion rates at work (e.g. 11:00 AM-3:00 PM), home (e.g. 6:00 PM-10:00 PM) and during sleep (e.g. 10:00 PM-6:00 AM) were compared between 73 employed women with family histories of breast cancer in first degree relatives (FH+; age=36.8+/-8.7) and 81 without such family histories (FH-; age=38.1+/-9.4). Differences in sympathetic adrenal medullary responses to an ordinary life stressor (work) were assessed in naturalistic settings. Repeated measures MANCOVA with family history group as a fixed factor, body mass index as a covariate and daily microenvironment (work, home and sleep) as a repeating factor were conducted to evaluate whether catecholamine excretion rates differed between FH+ and FH- groups. The results revealed that women with family histories of breast cancer had a higher rate of epinephrine excretion while at work (p<0.005). In addition, women in the FH+ group were also more reactive to the stress of work, showing a greater percentage of increase in both epinephrine and norepinephrine from sleep to work (p<0.05). The results also indicated that the chronic stress effects associated with a family history of breast cancer were moderated by BMI, such that their impact was more pronounced and apparent when women were not obese. These findings support the idea that the heightened neuroendocrine reactivity to experimental stressors in women at familial risk of breast cancer also occurs when women encounter stressors in ordinary life (work stress). Additional research to explore the health consequences of increased reactivity in women at familial risk of breast cancer, and perhaps in individuals at familial risk of other life-threatening disease, would appear warranted.

Physiological effects of shift work on hospital nurses.

The purpose of this study was to assess the physiological effects of shift work on the urinary excretion rates of norepinephrine, 6-sulfatoxymelatonin and estriol in hospital nurses. Twenty-four hour urine specimens were examined on a daytime/nighttime basis for each work shift of pregnant and non-pregnant subjects. The urinary norepinephrine and 6-sulfatoxymelatonin were measured by enzyme-linked immunosorbent assay and estriol by radio-immunoassay. Urinary norepinephrine level during the night work was higher than the night levels of the days off and the day shift. Urinary 6-sulfatoxymelatonin level during the night work was lower than the night levels of the days off and the day shift. Urinary estriol level of pregnant subjects showed no differences among work shift and also between daytime and nighttime. Urinary excretion rates of norepinephrine and 6-sulfatoxymelatonin were affected by shift work both for non-pregnant and pregnant subjects. It was unlikely that urinary estriol levels in the pregnant subjects were significantly affected by shift work.

Lorry drivers' work stress evaluated by catecholamines excreted in urine.

To evaluate lorry drivers' work stress by measurement of adrenaline and noradrenaline excreted in the urine, and to find out which factors in their working situation are related to the excretion rates of these catecholamines. The urinary excretion of adrenaline and noradrenaline of 32 lorry drivers, who also had loading and unloading activities to perform, was studied for one working day and one rest day. Each driver was asked to provide six urine samples on both days. For all samples, except the first (overnight) sample, the excretion rates of both catecholamines on the working day were higher than those on the rest day. Hierarchical multiple regression analyses were carried out to find out which factors in the drivers' working situation were related to the excretion rate of the working day. The excretion rate of adrenaline on the rest day, age, and psychosomatic complaints were positively related to the excretion rate on the working day (all P < 0.05). Body mass index and physical workload during loading and unloading were positively related to noradrenaline excretion rate (both P < 0.01). Psychosocial job strain did not significantly contribute to the proportion of variance explained in the excretion rates of both catecholamines. The excretion rates of adrenaline and, especially, noradrenaline on the working day were higher than those found in earlier studies among professional drivers and insufficient recovery took place after the work was ended. The only association between excretion rate on the working day and work stressors was found for noradrenaline and physical workload. The drivers' sympathoadrenal medullary reactivity to everyday work demands shows the characteristics of sustained activation.

Noradrenergic and adrenergic functioning in autism

A neurochemical assessment of noradrenergic and adrenergic functioning was carried out with autistic patients and normal control individuals. Norepinephrine and related compounds were measured in autistic (n = 17 unmedicated, 23 medicated; age range 9-29 years old) and normal controls (n = 27; age range 9-36 years old). Plasma levels and urinary excretion of 3-methoxy-4-hydroxy-phenylglycol (MHPG) were measured, as were urinary excretion rates of norepinephrine (NE), epinephrine (EPI), and vanillylmandelic acid (VMA). No significant group mean differences were seen between the autistic and control groups. In both the autistic and control groups urinary excretion rates of norepinephrine and epinephrine were substantially higher in the afternoon-evening (5-11 PM) compared to the overnight (11 PM-7 AM) collection period. Based on our neurochemical assessment, marked abnormalities in basal noradrenergic functioning do not appear to be present in autism.

Positive relationship between the catecholaminergic turnover and the DST results in depression

In the past some workers have reported positive relationships between indices of noradrenaline activity and measures of hypothalamic-pituitary-adrenal (HPA)-axis function. In order to investigate these relations, the authors measured noradrenaline, adrenaline and vanillylmandelic acid (VMA) in 24 h urine samples of 72 depressed females. Serum adrenocorticotrophic hormone (ACTH) and cortisol concentrations were determined before and after administration of 1 mg of dexamethasone. Cortisol non-suppressors exhibited a significantly higher noradrenaline, adrenaline and VMA excretion as compared to cortisol suppressors. We determined significantly positive correlations between the postdexamethasone cortisol values and the excretion rates of noradrenaline and VMA. These indices of noradrenaline activity correlated neither with the baseline cortisol and ACTH nor with the postdexamethasone ACTH values.

Influence of parenteral nutrition on rates of net substrate oxidation in severe trauma patients

Optimal nutritional support should use a patient's energy expenditure as a guide for administering sufficient but not excessive caloric intake. Eight patients requiring parenteral nutrition were evaluated, using indirect calorimetry measurements, to determine the nutritional influence on the rates of substrate utilization in the critical period of catabolic illness due to accidental trauma. Five days of total parenteral nutrition, providing calories to match the measured basal resting energy expenditure and N to replace the initial urinary losses a) shifted the RQ from 0.74 +/- 0.03 to 0.81 +/- 0.03, b) improved but could not reverse negative N balance, c) decreased net fat oxidation, d) increased carbohydrate and protein oxidation, e) elevated daily norepinephrine and epinephrine excretion rates, and f) attained positive energy balance. The results suggest that positive energy balance could be achieved in trauma patients by providing total energy intake matching their basal measured energy expenditure plus 7% to 10% for activity energy expenditure. To prevent further loss of lean body mass, an N intake of 350 mg/kg.day was needed in these catabolic ICU patients.

Modernization and catecholamine excretion of young Samoan adults

Urinary catecholamine excretion rates have been used as a cross-culturally valid measure of generalized stress. The purposes of this paper are to examine group differences in catecholamine excretion rates in three Samoan groups who differ in degree of modernization and to compare these findings to rates of norepinephrine and epinephrine excretion in other populations. In 1986-1987, 24-hr urine samples were collected from 18-37-year-old Samoans; 46 rural Western Samoan villagers, 53 American Samoans, and 49 Samoans residing in Honolulu. The results show that norepinephrine excretion is significantly higher in more modernized Samoan groups (P less than 0.05), while epinephrine excretion is not significantly different in the three groups. The higher norepinephrine excretion rate in the more modernized Samoan groups may be related to differences in relative work load associated with changes in body weight, work capacity, and work patterns which accompany modernization. Samoan epinephrine excretion rates are relatively high compared to the results of other population studies, while norepinephrine excretion in three Samoan samples ranged from among the lowest rates observed worldwide to among the highest.

Multiple endocrine neoplasia.

The MEN syndromes continue to be the focus of considerable interest and research. Since successful treatment requires early diagnosis, proper screening and follow-up of patients at risk is important. In the individual at risk for developing MEN IIa, annual screening should include measurement of the basal and stimulated plasma CT levels, and determination of plasma levels of calcium, PTH, and CEA. Twenty-four hour urine excretion rates of norepinephrine, epinephrine, metanephrine, dopamine, and VMA should also be obtained. It is our recommendation that this screening be continued through the third decade of life. Patients having thyroidectomy for MTC need to be tested annually for recurrent MTC and the development of adrenal medullary disease. All patients at risk for developing MEN IIb should be evaluated in a similar fashion. Recently, several groups using DNA linkage analysis have mapped the gene for MEN IIa to chromosome 10, although the exact location of the gene is yet to be determined. Preliminary linkage studies have mapped the gene for MEN I to chromosome 11. The identification of the genes for MEN I and MEN II will greatly simplify the diagnosis of the disease and perhaps also the therapy of affected patients.