Free Catecholamines Research Articles

The effect of the mode of delivery on the maternal–neonatal erythrocyte membrane acetylcholinesterase activity

Free radical production and high catecholamine levels are implicated with the modulation of acetylcholinesterase (AChE) activity. Objective To investigate the effect of the mode of delivery on maternal–neonatal erythrocyte membrane AChE activity. Subjects and methods Some women with normal pregnancy ( N = 30) were divided into two groups: group A ( N = 16) with normal labour and vaginal delivery and group B ( N = 14) with scheduled Cesarean section, twenty non-pregnant women were the controls. Blood was obtained from controls and from mothers pre- vs post-delivery as well as from the umbilical cord (CB). Total antioxidant status (TAS), membrane AChE activities and catecholamine blood levels were measured with a commercial kit, spectrophotometrically and HPLC methods, respectively. Results TAS and catecholamine levels as well as membrane AChE activities were similar in the two groups of mothers pre-delivery and in controls. TAS levels were reduced whereas AChE activities and catecholamine levels were increased post-delivery in mothers of group A and unaltered in group B at the same times of study. AChE activity was similarly lower in the CB of neonates than those of their mothers pre-delivery. Conclusions During a normal delivery process, the low TAS, the increased levels of catecholamines and the increased AChE activity, post-delivery, may be due to the increased stress due to the participation of uterus and skeletal muscles as during endurance exercise. The low AChE activity in newborns may be related to perinatal immaturity.

Parkinson's disease: the effect of L-dopa therapy on urinary free catecholamines and metabolites

L-dopa is an important antiparkinsonian drug. It is a precursor of dopamine and the other catecholamines. Potentially, administration of L-dopa could lead to increased urinary excretion of catecholamines and their metabolites to abnormal amounts. The current study aimed to determine these excretions in patients with Parkinson's disease (PD) receiving L-dopa compared with suitable controls. This is the first assessment of the effect of exogenous administration of L-dopa on urinary free metadrenalines. Using one-way analysis of variance (ANOVA), urine catecholamines and metabolites, expressed as mmol per mole creatinine, were compared in: patients with PD who were receiving L-dopa; patients with PD but not receiving L-dopa; and patients without PD who were being investigated for the presence of phaechromocytoma but were found not to have the disease. Significantly higher values for urinary dopamine, homovanillic acid, free normetadrenaline and free metadrenaline were found in patients with PD receiving L-dopa compared with the other two control groups. In all the patients with PD, these four analytes were significantly correlated with daily dose of L-dopa. L-dopa therapy can result in production of false positives for urinary excretion of dopamine, homovanillic acid, free normetadrenaline or free metadrenaline and thereby decrease the diagnostic value of these measurements in identifying phaeochromocytoma and related tumours.

Bilateral Adrenal Masses Due to Histoplasmosis

A 40-YR-OLD diabetic, normotensive man presented with weight loss and epigastric discomfort for 6 months. Chest x-ray was normal. Computed tomography (CT) scan revealed bilateral adrenal masses (Fig. 1A). The second patient, a 58-yr-old hypertensive, nondiabetic man, presented with anorexia and weight loss for 5 months. Chest x-ray revealed mediastinal widening. CT scan showed aortic dissection without mediastinal lymphadenopathy and incidental bilateral adrenal masses (Fig. 1B). Both patients had no history of tuberculosis; their HIV serology was negative. The 250g cosyntropin stimulation test was abnormal in the first patient (peak serum cortisol, 116 nmol/liter); he was commenced on hydrocortisone replacement. Urinary free catecholamine and metanephrine levels were normal in both. CT-guided fine needle aspiration cytology from the adrenal gland (Fig. 2) revealed features of histoplasma species in both; culture confirmed histoplasma capsulatum. They were treated with oral itraconazole (200 mg daily), the first patient for 15 months and the second for 6 months. Follow-up CT scans showed resolution of the adrenal masses in the first patient 5 yr later; he continues to have normal adrenal function at 9 yr. The adrenal masses have reduced in size in the second patient, but remain enlarged in the absence of any clinical disease at 18 months. CT features of adrenal histoplasmosis vary depending on the stage of the disease. Typically, it includes bilateral adrenal masses with peripheral enhancement and central hypodensities, with calcification seen in the healing phase. Similar features might be seen in adrenal neoplasms, subacute adrenal hemorrhage, and other disseminated infections, such as tuberculosis, cryptococcosis, coccidioidomycosis, and blastomycosis (1–5).

Phaeochromocytoma: current concepts

The discovery of novel mutations in genes encoding succinate dehydrogenase subunits has revealed that familial phaeochromocytomas are much more common than previously thought. Genetic screening should be offered to patients with apparently sporadic phaeochromocytomas and their first-degree relatives. An increasing proportion of phaeochromocytomas present preclinically on genetic testing or as "incidentalomas" on abdominal imaging, rather than with classic symptoms and signs. Clinical suspicion should prompt measurement of plasma levels of free metanephrine or 24-hour urinary catecholamine and metanephrine levels, followed, if positive, by tumour localisation studies. With appropriate perioperative care, surgical management of phaeochromocytomas is safe and effective. Most tumours can be removed laparoscopically.

Reduced adiposity in bitter melon (Momordica charantia) fed rats is associated with lower tissue triglyceride and higher plasma catecholamines

Slower weight gain and less visceral fat had been observed when rats fed a high-fat diet were supplemented with freeze-dried bitter melon (BM) juice; the metabolic consequences and possible mechanism(s) were further explored in the present study. In a 4-week experiment, rats were fed a low-fat (70 g/kg) or a high-fat (300 g/kg) diet with or without BM (7.5 g/kg or 0.75%). BM-supplemented rats had lower energy efficiency, visceral fat mass, plasma glucose and hepatic triacylglycerol, but higher serum free fatty acids and plasma catecholamines. In the second experiment, 7-week BM supplementation in high-fat diet rats led to a lowering of hepatic triacylglycerol (P<0.05) and steatosis score (P<0.05) similar to those in rats fed a low-fat diet. BM supplementation did not affect serum and hepatic cholesterol. However, plasma epinephrine and serum free fatty acid concentrations were increased (P<0.05). In the third experiment, BM(7.5 and 15 g/kg) and 1.5 % BM lowered triacylglycerol concentration in red gastrocnemius and tibialis anterior (P<0.05) muscle, but a dose-response effect was not observed. These data suggest that chronic BM feeding leads to a general decrease in tissue fat accumulation and that such an effect is mediated in part by enhanced sympathetic activity and lipolysis. BM or its bioactive ingredient(s) could be used as a dietary adjunct in the control of body weight and blood glucose.

Plasma metanephrines in renal failure

Diagnosis of pheochromocytoma in renal failure poses a diagnostic dilemma due to lack of reliability of conventional urinary measurements of catecholamine excess. Measurements of the plasma metanephrines, normetanephrine and metanephrine (the O-methylated metabolites of norepinephrine and epinephrine), provide an alternative diagnostic test. The metanephrines may be measured as free metabolites or after a deconjugation step where measurements reflect mainly sulfate-conjugated metabolites. The influence of renal insufficiency states on these various measurements is unclear. Plasma free and deconjugated metanephrines and catecholamines in 17 patients on dialysis with end-stage renal disease and 19 patients with renal insufficiency (creatinine clearance, 5-78 mL/min) were compared with levels in 89 hypertensives, 68 healthy normotensives, and 51 patients with von Hippel-Lindau syndrome. Patients with renal failure had up to two-fold higher plasma concentrations of catecholamines and free metanephrines, and more than 12-fold higher plasma concentrations of deconjugated metanephrines than comparison groups. Plasma free metanephrines and catecholamines were, respectively, within the 95% confidence intervals of reference groups in 75% and 42% of the dialysis patients, and in 74% and 68% of patients with renal insufficiency. In contrast, no dialysis patient and only half the renal insufficiency patients had plasma levels of deconjugated metanephrines within the reference intervals. Plasma levels of deconjugated metanephrines, but not free metanephrines, showed strong inverse relationships with creatinine clearance. Plasma concentrations of free metanephrines are relatively independent of renal function and are, therefore, more suitable for diagnosis of pheochromocytoma among patients with renal failure than measurements of deconjugated metanephrines.

Präoperative Katecholamin-Effekte auf Blutfette und Magnesiumwerte können ein Leberversagen nach Leberresektionen vorhersagen

BACKGROUND: Our previous investigations demonstrated that there is an enormous increase in free catecholamines during prolonged intraoperative occlusion of blood flow to the liver (Pringle maneuver), with tachycardias indicating impending postoperative liver failure. As stress-induced changes in catecholamine levels also have clear metabolic consequences, we investigated changes in catecholamines and their metabolites before, during, and after surgery, looking for simple risk parameters that could serve as early onset predictors of postoperative liver failure. METHODS: We examined 26 patients with primary and secondary liver tumors. Their average age was 54 years (range, 27–79). Twenty-one patients had segmental liver resections, 3 had hemihepatectomies, and 2 hydatid cysts were treated by pericystectomy. Blood samples were taken 2 days before and during all phases of surgery and the following parameters were determined: free plasma epinephrine, total serum calcium and magnesium, serum triglycerides, and serum cholesterol. Catecholamine plasma values were determined by high-performance liquid chromatography. The patients were subdivided into 2 groups: one including those with postoperative liver failure; and the other, those without liver failure. Statistical analysis was performed with Clinical Stress Assessment Software. RESULTS: In patients with liver failure (LF), perioperative catecholamine increase was about threefold higher when compared to the increase observed in non-liver failure patients (nLF). However, there were no preoperative differences in catecholamine levels among the groups. Unlike the results for the catecholamines, there were significant preoperative differences in cholesterol, triglycerides, and total magnesium values, which were all lower in the LF group. Perioperative fall in cholesterol correlated significantly with decreased calcium levels, an electrolyte well known to be discharged from the blood stream into tissues with increasing catecholamine effect. Such an increase could also be shown by perioperative positive correlations between glutamic oxalacetic transaminase and epinephrine. CONCLUSIONS: Estimation of the risk of postoperative liver failure is of great importance for the surgeon and the patient. Disproportionately large increases in catecholamines in the LF group point towards a relative increase in surgical stress in persons who already are metabolically maladapted. Such metabolic exhaustion is well documented by preoperative "pseudonormal", i.e., relatively low cholesterol and triglyceride levels, that are usually not to be expected in middle-aged patients. Along with low magnesium concentrations, such parameters can be used as preoperative predictors for postoperative liver failure.

Paracetamol-associated interference in an HPLC-ECD assay for urinary free metadrenalines and catecholamines.

Some high-performance liquid chromatography techniques with electrochemical detection for urinary catecholamines and their metabolites can be subject to interference from drugs and their metabolites. Prime amongst these interferences are those due to paracetamol ingestion. The prevalence of paracetamol contamination was determined by measuring the drug in all patient specimens submitted for catecholamine analysis over a 2-month period. These findings were then related to the proportion of unreportable results at each range of specimen paracetamol concentration. The apparent results from a small representative sample of the paracetamol-positive specimens are illustrated. Approximately one-third of urine specimens were found to contain paracetamol. Low-level contamination can produce apparent patterns of results which may easily be confused with those found in predominantly adrenaline-, or metadrenaline-secreting phaeochromocytomas. Despite the fact that significantly less than 5% of an oral dose of paracetamol is excreted as the free drug, its analysis provides a good surrogate marker for the likelihood of spurious results. It is useful to know prior to urinary free metadrenaline or catecholamine analysis which urine specimens are likely to contain potentially interfering paracetamol metabolites.

Formate buffer as preservative for urinary free catecholamine measurement.

Strong mineral acid is the most commonly used preservative for measuring urinary free catecholamines. Leakage of corrosive acid is a safety hazard. The use of formate buffer as a safer alternative was studied. Twenty-two urine specimens from post-operative patients were collected and preserved in 0.5 M hydrochloric acid or 0.75 M formate buffer. The specimens were stored at 4 degrees C or -70 degrees C, respectively. The free catecholamine content was measured at regular intervals by high-performance liquid chromatography for 6 months. The preservation capability of formate buffer was equivalent to that of hydrochloric acid. Deep-freeze storage offered additional protection independent of the preservative used. The results of this study demonstrate that formate buffer, compared to the most popularly used strong mineral acid solution, is an equally effective preservation for urinary free catecholamines. The less acidic nature of formate should invite fewer unpleasant incidents and safety hazards.

Structure–activity relationship of coordinated catecholamine in the [Ru III(NH 3) 4(catecholamine)] + complex

The redox chemistry and pharmacological studies of the novel blue ruthenium(III)–catecholamine complexes were investigated in aqueous medium and compared to the free catecholamines. The [Ru III(NH 3) 4(catecholamine)] + can be oxidized or reduced reversibly in one electron redox couples in aqueous solution. This is in contrast to the free catecholamines, which has a complicated electrochemical behavior due to coupled protonation process. The introduction of the ruthenium group reduces the intrinsic efficacy of the studied catecholamines. The [Ru III(NH 3) 4(catecholamine)] + complex aqueous medium is more stable than the free catecholamines ligand in the same conditions.

Retrospective analysis of abnormal 24-h urinary free catecholamine concentration in screening for phaeochromocytoma.

Patients with hypertension often have increased 24-h excretion of urinary free catecholamines (UFCA) compared with normotensive patients, but the extent to which beta-blockade and other antihypertensive agents affect 24-h UFCA concentrations remains unclear. Consequently, many patients with slightly elevated 24-h UFCA concentrations are not adequately investigated for the presence of phaeochromocytoma. We undertook a retrospective study on patients with at least one abnormal 24-h urinary collection of adrenaline (Adr), noradrenaline (NA) or dopamine (DA) between July 1997 and December 1999 to assess these issues. Of the 168 patients identified with raised 24-h UFCA concentrations, 106 with hospital notes were audited. Of the 46 patients whose values were more than twice the upper reference limit, 24 had their result confirmed with a repeat sample and only 10 underwent computed tomography or m-iodobenzylguanidine scanning. Two patients of these 10 had a phaeochromocytoma. We observed that hypertension correlated with significantly increased NA excretion compared with normotensive patients (median value 490+/-222 nmol per 24 h versus 304+/-229 nmol per 24 h, P<0.005). Patients on beta-blockers showed a trend towards significantly increased NA excretion (P=0.08). Many patients with abnormal 24-h UFCA excretion are not thoroughly investigated for the presence of phaeochromocytoma. NA concentration is significantly raised above the reference limit for patients with hypertension, and the use of beta-blockers showed a trend towards a further elevation in NA concentrations. Care must therefore be taken when interpreting abnormal NA concentrations in patients with hypertension or in those taking beta-blockers.

Antifungal activity of novel catecholamine ruthenium(III) complexes

New catecholamine ruthenium(III) complexes with potentially interesting biological activity are described. The complexes were prepared by reacting catecholamine with [RuCl(NH3)5]Cl2. The newly prepared species were formulated as [RuIII(NH3)4(catecholamine-R)]n+ where catecholamine-R = noradrenaline, dopamine and isoproterenol, and were characterized by elemental analysis, e.p.r., electronic absorption and f.t.-i.r. They were moderately stable in water at room temperature for at least 1 week. In vitro tests of antifungal activity showed the ruthenium–catecholamine complexes had strong inhibitory action against the pathogenic yeast Candida albicans, Candida glabrata and Candida tropicalis. Free catecholamine does not show any antifungal activity.

Attomole Electrophoretic Analysis of Catecholamines Using Copper-Catalyzed Intramolecular Cyclization

Urinary catecholamines and metanephrines are biochemical indicators of pheochromocytoma. We developed and validated a rapid and precise analytical method based on solid-phase extraction (SPE) and liquid chromatography separation coupled to tandem mass spectrometry (LC–MS/MS) for measuring urinary free catecholamines and metanephrines in a clinical setting.Following SPE purification of catecholamines and metanephrines from urine specimens, chromatographic separation and quantitative detection were performed using LC–MS/MS. The developed method for simultaneous measurement of urinary free catecholamines and metanephrines was validated with clinical urine specimens and was compared with other clinical and biochemical results, including urinary total metanephrines, vanillylmandelic acid (VMA), and plasma free metanephrines.The performance of our newly developed method for measuring urinary free epinephrine (EPI), norepinephrine (NE), dopamine (DA), metanephrine (MN), and normetanephrine (NMN), was acceptable. The recoveries and matrix effects of analytes were 61–107% and 84.5–130.7%. The linear ranges of each analyte were 3.8–2163 μg/L, 7.4–2,359 μg/L, 5.4–2,825 μg/L, 3.5–2,466 μg/L, and 3.7–2,569 μg/L, and the coefficients of variation (CV) were less than 10% with respect to imprecision. Carryover and sample stability were also validated. Validation using clinical urine specimens by comparison with various biochemical results showed that urinary free metanephrines had comparable sensitivity (100%) and superior specificity (97.1%) to urinary total and plasma free metanephrines.The facile and reliable simultaneous measurement method for urinary free catecholamines and metanephrines using LC–MS/MS developed in this study is helpful in obtaining information about multiple metabolites and is applicable to routine clinical settings for the screening of pheochromocytoma.

Diagnosis of overtraining: what tools do we have?

The multitude of publications regarding overtraining syndrome (OTS or 'staleness') or the short-term 'over-reaching' and the severity of consequences for the athlete are in sharp contrast with the limited availability of valid diagnostic tools. Ergometric tests may reveal a decrement in sport-specific performance if they are maximal tests until exhaustion. Overtrained athletes usually present an impaired anaerobic lactacid performance and a reduced time-to-exhaustion in standardised high-intensity endurance exercise accompanied by a small decrease in the maximum heart rate. Lactate levels are also slightly lowered during submaximal performance and this results in a slightly increased anaerobic threshold. A reduced respiratory exchange ratio during exercise still deserves further investigation. A deterioration of the mood state and typical subjective complaints ('heavy legs', sleep disorders) represent sensitive markers, however, they may be manipulated. Although measurements at rest of selected blood markers such as urea, uric acid, ammonia, enzymes (creatine kinase activity) or hormones including the ratio between (free) serum testosterone and cortisol, may serve to reveal circumstances which, for the long term, impair the exercise performance, they are not useful in the diagnosis of established OTS. The nocturnal urinary catecholamine excretion and the decrease in the maximum exercise-induced rise in pituitary hormones, especially adrenocorticotropic hormone and growth hormone, and, to a lesser degree, in cortisol and free plasma catecholamines, often provide interesting diagnostic information, but hormone measurements are less suitable in practical application. From a critical review of the existing overtraining research it must be concluded that there has been little improvement in recent years in the tools available for the diagnosis of OTS.

Study of diurnal fluctuations of plasma methoxyamines in healthy volunteers.

We studied the diurnal fluctuations of plasma concentrations of methoxyamines (metanephrine and normetanephrine) and of their parent amines (epinephrine and norepinephrine) in normotensive subjects. Serial blood sampling at 09.00 h, 11.00 h, 12.00 h, 14.00 h, 16.00 h, 18.00 h and 20.00 h in 28 healthy volunteers at rest. Determination of plasma concentrations of free catecholamines and total methoxyamines (free and sulpho-conjugates) was carried out by high-performance liquid chromatography with electrochemical detection. Mean (+/- SD) plasma concentrations of total metanephrine (MN) and normetanephrine (NMN) were 4.31 +/- 1.73 nmol/l (range: 0.96-9.3 nmol/l) and 8.13 +/- 2.54 nmol/l (range: 3.14-17.0 nmol/l), respectively. The NMN/MN ratio ranged between 0.8 and 7.8 (mean +/- SD 2.1 +/- 1.0). Mean plasma concentrations of free epinephrine and norepinephrine were 0.21 +/- 0.12 nmol/l (range: 0.06-1.39 nmol/l) and 1.61 +/- 0.62 nmol/l (range: 0.47-4.01 nmol/l), respectively. Despite marked intraindividual fluctuations, mean methoxyamine and catecholamine levels remained constant over the entire duration of the experiment. The absence of fluctuations of plasma levels of total methoxyamines suggests that their measurement could be carried out at any time within the diurnal time frame. Further investigations, however, remain necessary to validate these findings in patients with hypertension and/or pheochromocytoma, and to explain the ever important intraindividual variation in plasma concentrations of methoxyamines and of their parent compounds.

Effect of Hospitalization on Urinary Catecholamine Excretion in Patients with Hand‐Arm Vibration Syndrome

Effect of Hospitalization on Urinary Catecholamine Excretion in Patients with Hand‐Arm Vibration Syndrome: Mieko Iwamoto, et al. Department of Hygiene, Yamaguchi University School of Medicine—The purpose of this study was to investigate the effect of hospitalization for five weeks on the autonomic nervous activity of patients with hand‐arm vibration syndrome (HAVS). Urine samples were collected from ten patients with HAVS before, during, and after hospitalization. Amounts of urinary free catecholamines (norepinephrine, epinephrine and dopamine) were measured. Urinary excretion of norepinephrine and dopamine during hospitalization was significantly lower than that before hospitalization. The effect of hospitalization continued for 10 days after hospitalization. The results of this study suggest that hospitalization is useful for the treatment of patients with HAVS to reduce the sympathetic hyperactivity.

A Five-Year Report on Experience in the Detection of Pheochromocytoma

Objective: The purpose of the study is to identify biochemical tests that are good predictors for the diagnosis of pheochromocytoma in patients at hypertension. Setting: Review of data from of 3826 patients studied over a 5-year period, between 1994 and 1998, at the University Hospital “Virgen de la Arrixaca” Murcia, Spain. Design and Methods: A retrospective study for the diagnosis of pheochromocytoma of 24-h urinary free catecholamines (norepinephrine, epinephrine, and dopamine) measured by high-performance liquid chromatography (HPLC)-electrochemical detector (ECD), total metanephrines (MNt), and vanillylmandelic acid measured by spectrophotometric methods. Results: During this period, 57 patients were found to have pheochromocytoma, being 47 sporadic, 9 with multiple endocrine neoplasia type 2A, and 1 with neurofibromatosis. In all patients multiple endocrine neoplasia type 2A the tumor were bilateral but only in four of the sporadic tumor group ( p < 0.0001, Fisher’s exact test). MNt was determined to be the best discriminator of hypertension and pheochromocytoma. It scored a sensitivity of 94.7% (95% confidence interval, 88.3–99.9%), a specificity of 95.3% (89.5–99.9%), and thus had the best negative predictive value of 99.9% (99.8–99.9%), and this biochemical test also had the best positive predictive value of 23.3% (10.8–59.9%). When combining both MNt and norephinephrine, the positive predictive value to increases to 85.6% (65.3–95.6%). Conclusion: Urinary 24-h MNt excretion level is the best single biochemical test for screening and, in combination with norephinephrine, is diagnostic of the presence of pheochromocytoma.

Developmental changes in chemoreceptor nerve activity and catecholamine secretion in rabbit carotid body: possible role of Na+ and Ca2+ currents.

In order to better understand the post-natal increase in peripheral chemoreceptor responsiveness to hypoxia, chemoreceptors of newborn (1-2 days) and older (10-12 days, 30 days, adult) rabbits were isolated and superfused, in vitro. The free tissue catecholamine concentration was measured using carbon-fiber voltammetry and pauci-fiber nerve activity was recorded from the sinus nerve during stimulation (4 min) with graded hypoxia or increased potassium. Both the peak catecholamine and peak nerve responses to stimulation with 10% and 0% oxygen increased with age, particularly between 10 and 30 days of age. In contrast, peak nerve and peak catecholamine responses to increased potassium did not significantly change with age. For a better understanding of how responsiveness increases with age, the fast Na+ and the Ca2+ currents were measured from isolated glomus cells of newborn and older rabbits, but the magnitude of the currents when normalized to membrane area was not significantly different between ages. We conclude that: (1) rabbit chemoreceptors mature in the newborn period (10-30 days) and part of this maturation is an increase in catecholamine secretion, (2) maturation of hypoxia transduction primarily occurs in steps prior to depolarization since potassium-evoked responses were not affected, and (3) an increase in the magnitude of glomus cell fast Na+ or Ca2+ currents is not a likely mechanism for the maturational change, but changes in the oxygen sensitivity of these currents cannot be excluded.

Freedom from Drug Interference in New Immunoassays for Urinary Catecholamines and Metanephrines

Determination of urinary free catecholamine and total (i. e., free plus conjugated) metanephrine excretion is considered the most clinically sensitive biochemical test for pheochromocytoma. In this study, we evaluated new immunoassay methods for the measurement of these analytes for potential drug-based interference. Urine samples collected from patients on a variety of medications were grouped by specific drug type. The significance of any difference in the free catecholamine or total metanephrine concentrations in the different groups was assessed by one-way ANOVA. A group of patients receiving no medication was included as a control (no analytical interference). Additionally, analytical accuracy, detection limit, and precision were determined. No significant differences were found in the concentrations of free catecholamines or total metanephrines in urine from patients taking the medications investigated and the control group: P = 0.649 (fE), 0.221 (fNE), 0.149 (tM), and 0.170 (tNM). For free catecholamines, intraassay CVs were 4.6-18%; interassay CVs were 10-25%. For total metanephrines, intraassay CVs were 9.6-27%; interassay CVs were 5. 8-22%. Detection limits were 0.009 and 0.027 micromol/L for fE and fNE and 0.119 and 0.346 micromol/L for tM and tNM, respectively. None of the drugs examined in this study interfered in the measurement of free catecholamines or total metanephrines by these immunoassays. The technique is easier to use, requires less equipment, and is more accessible than HPLC. In combination, these assays are suitable as initial screening tests for pheochromocytoma.

Liver ischemia, catecholamines and preoperative condition influencing postoperative tachycardia in liver surgery

The aim of our study was to assess the influence of intraoperative hypoxic stress -unavoidably brought about by so called Pringle maneuver — on free and conjugated catecholamines during major hepatic resection. Judging from earlier results of fatigue-experiments in rats we also wanted to check the relationship between of poor general preoperative condition and conspicuously low triglyceride serum concentrations. The study included 26 patients with primary and secondary liver tumors. The mean age was 54 years (range 27–79). Twenty-one patients had segmental liver resections, 3 had hemihepatectomies and 2 hydatid cysts were treated by cystectomy. Blood samples were taken 2 days before and throughout surgery. Catecholamine plasma values were determined by high performance liquid chromatography. Statistical comparisons were made by t-test, ANOVA and chi square test. Free plasma catecholamines increased significantly during prolonged intraoperative ischemia (Pringle time 50–125 minutes). Patients with elevated intraoperative catecholamines had a significant correlation to postoperative episodes of tachycardia, and prolonged hospital stay. On the other hand, we could also see postoperative tachycardias in patients with short Pringle times (18–49 minutes) but with decreased preoperative serum triglycerides as an indicator of chronic stress and reduced general condition. Intraoperative hypoxic stress is associated with increased catecholamine values. Elevated catecholamines may well cause postoperative sinustachycardias (mean 20 hours) and are strongly related to postoperative liver failure and prolonged hospital stay.