Quantitation of urinary normetanephrine and metanephrine by reversed-phase extraction and mass-fragmentographic analysis

Hydrolyzed urine with added ring-trideuterated normetanephrine and metanephrine is applied to wet C18-reversed-phase minicolumns. The "metanephrines" are eluted, dried, derivatized with pentafluoropropionic anhydride, and analyzed with the gas chromatograph-mass spectrometer. Ions for the nondeuterated and trideuterated compounds are monitored at ml z 458 and 461, respectively. For both normetanephrine and metanephrine, the standard curve is linear over the range 10-2000 micrograms/L and the procedure has adequate precision both within-run (CV less than 3%) and between-day (CV less than 7%). Alkaline pH in the extraction is important for optimal analytical recovery. We have examined the potential value of untimed urine specimens for screening purposes and compared 24-h urine concentrations of these analyses in normotensive and hypertensive persons.

Scintigraphic localization of pheochromocytoma

We used a new radiopharmaceutical agent, [131I]meta-iodobenzylguanidine ([131I]MIBG), to produce scintigraphic images of pheochromocytomas in eight patients. One day or more after injection, the only normal organ that displayed distinct concentrations of radioactivity was the urinary bladder. The [131I]MIBG was probably concentrated in adrenergic vesicles; in tissues where vesicles are numerous, such as pheochromocytomas, the radionuclide was retained for days. The spectrum of pheochromocytomas shown the scintigrams was broad: intra-adrenal and extraadrenal in location, benign and malignant in character, 0.2 to 65 g in weight, and with different hormone patterns in secretion. Tumors in four patients were not detected by computed tomography. In one patient, reoperation was undertaken only because the scintigram located the extra-adrenal tumors and thereby directed the surgeon's exploration. The method offers hope of safe and reliable localization of pheochromocytomas in their many guises.

Analysis of urinary metanephrines by reversed-phase high-performance liquid chromatography and electrochemical detection

A sensitive and specific direct analysis of urinary normetanephrine (NMN) and metanephrine (MN) was achieved utilizing reversed-phase high performance liquid chromatography and electrochemical detection. Individual specimens from "control" subjects and those with pheochromocytoma were hydrolyzed and the metanephrines separated from other urinary constituents by elution with ammonia from a Dowex CG-50 resin. Chromatographic peaks were identified by retention behavior, co-chromatography with reference compounds, ratio of responses at various oxidation potentials and stopped-flow UV spectra of the collected fractions. The NMN and MN content for the control subjects was between 0.086 and 0.21 (mean - 0.14) microgram/mg creatinine and 0.012 and 0.092 (mean = 0.039) microgram/mg creatinine, respectively. The values for subjects with pheochromocytoma varied from 1.5 to 27.5 (mean = 9.9) microgram/mg creatinine for NMN and 0.10 to 1.60 (mean = 0.86) microgram/mg creatine for MN. The patient with ganglioneuroma had an NMN of 4.1 and an MN of 0.80 microgram/mg creatinine. While this method permits discrimination between those patients with pheochromocytoma and the overwhelming majority of hypertensive patients, it may ultimately be further extended to separate normal subjects from those with more subtle derangements in catecholamine metabolism.

Metabolism of D, L-3H-norepinephrine in essential hypertension

Defective control of the cardiovascular system by the sympathetic nerves continues to be incriminated as the potential primary physiologic defect in essential hypertension (EH). The need to measure sympathetic tone has progressed from physiologic mensuration by assessment of reflex and pharmacological responses to the recent assay of norepinephrine (NE) and its congeners in both urine and plasma. The way in which the body handles D,L-B-3H-NE represents yet another technique by which to evaluate sympathetic function. Previous studies of EH by this method demonstrated more rapid plasma disappearance of 3H-NE as well as elevated 24 hour tritium accumulation in the urine following D,L-B-3H-NE injection. The present study of 7 normotensive subjects and 7 patients with EH was designed to depict more precisely these abnormalities in 3H-NE-metabolism. Following a one minute injection of 8 micrograms D,L-B-3H-NE, (200 microCi) intravenously, the excretion of unlabeled endogenous metabolites and their labeled congeners was assayed. By these means one could estimate catecholamine synthesis, turnover of the labeled pools, and by comparison of relative specific activities of the metabolites, gain some insight into the distribution of the injected material. Alternative catabolic pathways were evaluated by measurement of the excretion of 3H2O. Patients with EH excreted more label per 24 hours, revealed a more rapid decline of 3H2O excretion and lower specific activity of normetanephrine (NM). These findings are compatible with changes in pool dynamics and distribution of administered label which gave additional support to the concept of adrenergic dysfunction in association with essential hypertension.

Catecholamine measures for diagnosis and treatment of patients with depressive disorders

Measurement of the catecholamine's, norepinephrine, epinephrine, metanephrine, normetanephrine, vanilmandelic acid, and 3-methoxy-4-hydroxyphenyl-glycol (MHPG) show certain statistical correlations with three clinical diagnoses. These conditions are as follows: 1) bipolar and schizo-affective depression, 2) unipolar nonendogenous depressions, and 3) schizophrenia related depressions. More specifically MHPG acts to predict which patients will require higher doses of medication, higher plasma levels, and longer treatment periods to respond to treatment.

A simple chromatographic technique for the estimation of urinary levels of normetadrenaline and metadrenaline

A simple, but effective, procedure is described for the concurrent estimation of normetadrenaline (NMA) and metadrenaline (MA) in urine. The 3-methoxycatecholamines are adsorbed by a cation exchange resin, desorbed, separated by paper chromatography, and finally estimated spectrophotometrically after oxidation to vanillin. The mean (+/- 2 standards deviations) urinary outputs of NMA and MA from 123 normals (80 males, 43 females) in 24 hours was 2.15 +/- 1.04 and 1.79 +/- 0.96 mu mol respectively. There was no significant difference in the 24-hour urinary outputs of NMA between the male and female groups. However, the output of MA from the males was significantly higher than that from the females.

A radioenzymatic assay for free and conjugated normetanephrine and octopamine excretion in man

A radioenzymatic method for the measurement of free and conjugated normetanephrine (NMN) and octopamine (OCT) is described for human urine. The assay is based on the conversion of NMN or OCT to radiolabeled metanephrine (MN) or synephrine (SYN) by phenylethanolamine-N-methyl transferase (PNMT), using tritium-labeled S-adenosyl-methionine [3H]SAM as methyl donor. Thin-layer chromatographic separation yields an assay of high specificity. The sensitivity of the assay is 5 and 2.5 pg of NMN or OCT, respectively. The normal value of free and conjugated NMN was found to be 23 +/- 13 and 102 +/- 49 ng/mg creatinine. Four patients with pheochromocytoma had highly increased levels of free and conjugated NMN. The urinary excretions of free and total octopamine were 5.7 +/- 2.8 and 34.8 +/- 16.6 ng/mg of creatinine, respectively, in normal patients.

Neonatal pattern of adrenergic metabolites in urine of small for gestational age and preterm infants

Catecholamines (DA, NE, E), methoxyamines (MT, NMN, MN), DOPA and DOPAC were studied in urine of term small for gestational age infants (SGA) and preterm with appropriate birthweights for gestational age (PT) during the first ten days of life. Results were compared to values obtained for full term infants (FT). As a whole no deficit in urine catecholamines was observed in either group of SGA and PT neonates suggesting that capacities to synthesize catecholamines are already developed at birth. Furthermore, in SGA infants, adrenergic function seems to be enhanced during the first four days of life; however, SGA infants with low blood glucose levels excreted amounts of epinephrine similar to those of FT neonates, but much lower than those obtained in normoglycemic SGA neonates. These data suggest that enhanced release of catecholamines is required in SGA infants to maintain the glycemic homeostasis. In premature infants, the adrenergic pattern was highly altered only in younger preterm neonates (31 weeks of gestational age) who excreted more catecholamines than older preterm babies (33 to 36 weeks) or full term neonates; this catecholamine increase in urine of young preterm infants might be related to immaturity of storage vesicles and/or to thermoregulatory or respiratory events. On the other hand, a striking deficit in excretion of DOPAC was observed in small for gestational age infants and in young preterm neonates during the first ten days of life. DOPAC excretion was even lower in SGA than in young preterm neonates. These findings suggest that the maturation of dopaminergic neurons occurs late in gestational age and is greatly dependent on nutritional factors.

Increased plasma and urinary normetanephrine in young patients with primary hypertension

1. Normetanephrine was measured in small samples of plasma and urine of hypertensive patients and normal volunteers (age 20-60 years) by a specific radioenzymatic assay with bovine adrenal phenylethanolamine N-methyltransferase and tritiated S-adenosylmethionine. 2. Noradrenaline was measured simultaneously in plasma and urine. 3. Plasma normetanephrine and noradrenaline concentrations varied in direct proportion to activation or suppression of sympathetic nerve function. 4. Both plasma and urinary normetanephrine concentrations were elevated in patients with phaeochromocytoma. 5. Plasma normetanephrine concentrations were related to plasma noradrenaline concentrations of hypertensive subjects. 6. Plasma normetanephrine and noradrenaline concentrations and urinary normetanephrine excretion rates were increased in some young patients with primary hypertension, suggesting that sympathetic nerve hyperactivity is a pathogenic factor in these patients.

Metabolic adrenergic changes during submaximal exercise and in the recovery period in man

The urinary excretion of dihydroxyphenylalanine (DOPA), catecholamines (CA) [dopamine (DA), norepinephrine (NE), and epinephrine (e)], their 3-O-methylated derivatives [3-O-methyldopamine (3-MT), normetanephrine (NMN), and metanephrine (MN)], and their deaminated metabolites [dihydroxyphenylacetic acid (DOPAC) and vanilmandelic acid (VMA)] was studied in six healthy men, at rest during short-term (15 min) or exhaustive submaximal exercise, and in the 2-h postexercise recovery period. During short-term exercise only NE and VMA excretions increased, whereas in postexercise period only DA output was enhanced. Exhaustive muscular work induced a rise in NE and E excretion during the test, and an increase in DA, NE, and NMN urinary levels during postexercise recovery, while the output of deaminated metabolites was unaltered. It is concluded that both release and synthesis of CA are stimulated by submaximal exercise, which induces, in addition to NE, a specific release of DA. A possible role of NE in lipid mobilization during recovery from exhaustive muscular work is evoked. The origin and role of released DA are also discussed.

Norepinephrine metabolism and clinical response to dextroamphetamine in hyperactive boys

The 24-hour urinary catecholamine metabolites 3-methoxy-4-hydroxyphenylglycol, normetanephrine, and metanephrine were measured in 23 hyperactive boys and 13 matched healthy controls. The hyperactive children excreted lower MHPG and higher NM (low MHPG/NM ratio) amounts than in controls. The administration of d-amphetamine in the dose of 0.5 mg/kg body weight divided over two doses daily for two weeks decreased MHPG excretion in the hyperactive children. When the hyperactive children group was divided into drug responders and nonresponders according to their pre- and post-treatment scores on the Conners Teacher Questionnaire, d-amphetamine administration decreased MHPG excretion in the responders and did not change it in the nonresponders. Percent decrease in MHPG excretion correlated significantly with percent change in the hyperactivity factor of the questionnaire on the Spearman Rank Order Correlation Coefficient. Pretreatment urinary metabolites did not differentiate the responders from nonresponders. It is suggested that a relationship between CNS norepinephrine metabolism and hyperactivity exists and that d-amphetamine may achieve its therapeutic action in hyperactive children by altering CNS NE metabolism.

Increased catecholamine excretion after labetalol therapy: a spurious effect of drug metabolites

Patients with essential hypertension were treated for four weeks with the alpha- and beta-adreno-receptor blocking agent labetalol. Urinary excretion of total catecholamines, metanephrine plus normetanephrine and vanillylmandelic acid was measured with various methods before and during treatment. An unidentified substance interfering with the fluorimetric method for catecholamines and the photometric assay for metanephrines caused falsely high values of those substances. Using appropriate methodology no changes of total catecholamines, metanephrine plus normetanephrine and vanillylmandelic acid excretion were found after labetalol therapy. Our findings are important in preventing errors in the diagnosis of pheochromocytoma as well as in the evaluation of the effects of labetalol on the sympathetic nervous system in man.

Age-related changes in catecholamine metabolites of human urine from birth to adulthood

Catecholamines (dopamine [DA], norepinephrine [NE], epinephrine [E]), methoxyamines (3-methoxytyramine [MT], normetanephrine [NMN], metanephrine [MN]), DOPA, and acidic metabolites (3,4-dihydroxyphenylacetic acid [DOPAC], vanilmandelic acid [VMA]) were determined in human urines from one day of age to adulthood, in order to investigate sympatho-adrenal development during life. All adrenergic compounds are present in neonate urines on the first day of life, but their postnatal evolution is quite different according to the nature of metabolites. Daily E, MN and VMA amounts remain low until the 10th month of life; daily NE, MT and DOPA levels increase progressively, but, in contrast, NMN amounts are already high in the neonatal period and increase only beyond the fourth year of age. DA is at either age the predominant catecholamine but its elimination is relatively more important in the neonatal period.

Toward a biochemical classification of depressive disorders. II. Application of multivariate discriminant function analysis to data on urinary catecholamines and metabolites

The previous article in this series reported on the differences in urinary excretion of 3-methoxy-4-hydroxyphenylglycol (MHPG) in patients with various clinically defined subtypes of depressive disorders. We now report that further biochemical discrimination among depressive subtypes is provided by the following equation, derived empirically by applying multivariate discriminant function analysis to data on urinary catecholamine metabolits: Depression-type (D-type) score = C1(MHPG) + C2(VMA) + C3(NE) +C4(NMN + MN)/VMA + C0. In the original derivation of this equation, low scores were related to bipolar manic-depressive depressions, and high scores were related to unipolar nonendogenous (chronic characterological) depressions. Findings from a series of depressed patients whose biochemical data had not been used to derive this equation confirmed these differences in D-type scores among subtypes of depressions. The findings presented in this report further suggest that we can discriminate three biochemically discrete subgroups of depressive disorders.

Toward a biochemical classification of depressive disorders. I. Differences in urinary excretion of MHPG and other catecholamine metabolites in clinically defined subtypes of depressions

The urinary excretion of 3-methoxy-4-hydroxyphenylglycol (MHPG) and other catecholamine metabolites was measured in a series of 63 patients with various clinically defined subtypes of depressive disorders. MHPG excretion was significantly lower in patients with bipolar manic-depressive depressions and schizo-affective depressions than in patients with unipolar nonendogenous depressions. Patients with schizophrenia-related depressions also excreted reduced levels of MHPG when compared with patients with unipolar nonendogenous depressions. Moreover, levels of urinary epinephrine and metanephrine were significantly lower in patients with schizophrenia-related depressions. These data, coupled with our recent finding that patients with schizophrenia-related depressions had significantly higher levels of platelet monoamine oxidase activity than control subjects of patients with unipolar endogenous depressions, suggest that we can discriminate three biochemically discrete subgroups of depressive disorders corresponding to the following clinically defined subtypes: (1) the bipolar manic-depressive depressions plus the schizo-affective depressions; (2) the unipolar nonendogenous depressions; and (3) the schizophrenia-related depressions.

[Effect of submaximal muscular exercise of short duration on urinary excretion of catecholamines, DOPA and their metabolites]

Thirteen human subjects were submitted to a moderate muscular work on ergometric bicycle (at intensity corresponding to 80% of maximal oxygen uptake during 10 min). No modifications were observed in the urinary amounts of the three catecholamines (A, NA, DA), DOPA, DOPAC and 3-MT. On the contrary, the excretion of metadrenaline (MN) and normetadrenaline (NMN) was slightly increased, showing a mild stimulation of adrenergic system. Our result point out the interest of urinary methoxyamines as useful index of adrenergic activity in man. For experimental and physiopathological use, the metabolic alteration induced by a short submaximal muscular work is negligible for most adrenergic compounds, except for MN and NMN, the amounts of which are slightly modified.

Clinical and biochemical heterogeneity of depressive disorders

Indirect evidence, mostly pharmacologic, has suggested a role for brain neurotransmitter amines such as norepinephrine in the production of depression or mania. Clinical investigations have supported this concept but also indicate that depression is probably a biochemically heterogeneous group of illnesses. There may be a clinically, biochemically, and pharmacologically definable subtype of depression in which there is a disorder of norepinephrine metabolism or disposition in brain. I review here the experimental data from which this hypothesis is derived.