Με την βοήθεια του translate google έκανα την μετάφραση από τα Σουηδικά στα Αγγλικά από τον σύνδεσμο του προηγούμενου post:PheochromocytomaBiochemical diagnosticsThe diagnosis of pheochromocytoma is primarily biochemical.Determination of catecholamines and / or metabolites in urine and plasma / serum are the cornerstones of the investigation. Degradation of endogenous catecholamines occurs continuously within the tumor by the action of catecholamine-O-transferase (COMT) to metoxynoradrenalin and metoxyadrenalin or 3 metoxytyramin regarding dopamine-producing tumors. These metabolites released by diffusion continuously from the cells and is independent of the secretory release via exocytosis of granules which contribute to their higher sensitivity and specificity in the diagnosis of pheochromocytoma than the parent catecholamine. Excretion profile of catecholamines can provide guidance to the tumor localization and e v genetic origin. Hereditary tumors from Cluster 2 is almost always the adrenaline-producing and localized to the adrenal glands. However do not apply the reverse of noradrenaline producing tumors located outside the adrenal glands. One example is pheochromocytoma in Von Hippel-Lindau disease, which in principle is only norepinephrine-producing although they are localized to the adrenal glands. SDHx tumors of the adrenal glands is less common but also typical norepinephrine production in the localization.
Plasma and serum ASSAYSFree p-metoxynoradrenalin (normetanephrine, see reference below) and the RPS-metoxyadrenalin (metanephrine ref <0.3 nmol / L). Considered today as the first analysis. The sensitivity is 98% and specificity 87%. The levels of metoxynoradrenalin increases with age so age-adjusted normalized values have been proposed. New age-adjusted upper reference values have been introduced at the Karolinska University Hospital: 0-18 years 0.5 nmol / L, 19-29 0.6 nmol / L, 30-39 years 0.7 nmol / L, 40-49 0.8 nmol / L, 50-590 0.9 nmol / L> 60 years of 1.1 nmol / L.
A normal value in principle exclude pheochromocytoma. Free p-norepinephrine (ref <2.8 nmol / L) and the fp-adrenaline (ref <0.5 nmol / L). The sensitivity was 84% and specificity 88%.
Free p-3-metoxytyramin (ref <0.2 nmol / L), the corresponding methylated metabolite of dopamine metabolism and considered as the best analysis to reveal dopamine production of paraganglioma and neuroblastoma. Note that the analysis of this dopamine to 90% are locally in the kidney dopamine produced and have low sensitivity and specifictitet for capturing dopamine production from tumors.
S Chromogranin A (ref <4 nmol / L) is a protein which is released together with catecholamines by exocytosis of granules in the adrenal medulla. Sensitivity 86%, specificity 74%. Elevated kromograninnivåer seen in renal impairment and the use of proton pump inhibitors, why the specificity may be lower.
Klonidinhämningstest (normal outcome is a reduction of p-norepinephrine at least 40% or lower down within the reference range). Sensitivity 67% and specificity of 97%. The test is done preferably with medicinfri patient and drugs that affect the sympathetic nervous system should be discontinued 48 hours before the test. P catecholamines is determined -15, 0, 120 and 180 minutes after ingestion of 300 micrograms Catapresan p.o. Blood pressure and pulse followed every 30 minutes during the test. Patients should be confined to bed and have the indwelling needle when there is risk of pronounced hypotension. Not suitable for isolated adrenaline increase.
URINE ANALYSESMetoxykatekolaminer in urine (you-metoxynoradrenalin ref <2.5 ĩmol / d and metoxyadrenalin ref <1.5 ĩmol / d). Sensitivity 87%, specificity 92%.
Free catecholamines in urine (you norepinephrine, ref <400 nmol / d and you-adrenaline ref <80 nmol / d). Sensitivity 90% and specificity of 89%.
Urine-HMMA (VMA ref <35 ĩmol / d). Sensitivity 59% and specificity of 93%.
Slight elevation of catecholamines and their metabolites are common in stressed and anxious patients, which may be difficult to distinguish from patients with pheochromocytoma under development.
With the help of inhibition tests, such as clonidine, which inhibits the sympathetic activity in stressed individuals, but does not affect the autonomous mini catecholamine secretion from pheochromocytomas can usually stress-katekolaminförhöjning revealed.
Determination of catecholamines and metoxykatekolaminer in urine night, when the sympathetic activity is lowest, has also been shown to increase the sensitivity and specificity for accurate diagnosis.
Both sleep and bed rest reduce sympathetic activity. Night Urine Collection is practically easier to implement than 24 hours of collection. The individual laboratory must be able to present its own reference range.
Suggested biochemical examination time
Fractionated metoxykatekolaminer plasma or day / night urine is the first analysis according to international consensus. You-free catecholamines in one to two daily or night amounts is an option at the lack of availability of the primary analysis. At most pheochromocytoma is the secretion of catecholamines or its methoxylated metabolites elevations> 2-3 times above the respective reference value limits. A normal free-plasma metoxykatekolamin in principle exclude the diagnosis.
At slightly elevated levels in the urine (<2 times), the man uncertain diagnosis supplement with analysis of chromogranin A and make urine collection for catecholamines alternative methoxy-catecholamines according to the analysis conducted primary.
Klonidintest made in third place.
To increase the chance of catching urinkatekolaminnivåer elevated in patients who have been attacked in the low frequency, can provide the patient with urine collection containers to be used during the 4 hours following the attack.
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Θέμα: Ποιες βιοχημικές εξετάσεις παραγγέλνετε όταν υποψιάζεστε φαιοχρωμοκύττωμα; (Αναγνώστηκε 9855 φορές)
8 Μαΐου 2009, 16:45:23