and Creatinine

Laboratory assay overview

This panel may aid in evaluating catecholamine-producing pheochromocytomas and paragangliomas (PPGLs). However, measurements of plasma free or urinary fractionated metanephrines (ie, the O-methylated catecholamine metabolites) are preferred for the initial biochemical evaluation of PPGLs because of their overall high diagnostic sensitivity [1]. To adjust for the concentration differences in random urine specimens, results are expressed as catecholamine to creatinine ratios.Most PPGLs secrete catecholamines and can cause catecholamine excess, resulting in hypertension, arrhythmia, and hyperglycemia. Left untreated, PPGLs often lead to life-threatening cardiovascular complications. The estimated prevalence of PPGLs is 0.05% to 0.1% in adults with hypertension and 1.7% in children with hypertension [2]. Recognizing the possibility of a PPGL and performing appropriate biochemical testing are crucial for the diagnosis [1]. Plasma or urine catecholamine levels may be used, in addition to metanephrine levels, to provide additional information during the initial biochemical evaluation of PPGLs (eg, when detecting dopamine-secreting paragangliomas) [2].Intermittent or insignificant secretion of catecholamines by some PPGLs may not increase catecholamine measurements. Physiological stress and certain medications (eg, acetaminophen, labetalol, and sotalol) may increase catecholamine measurements [1].The results of this test should be interpreted in the context of pertinent clinical and family history and physical examination findings.References1. Lenders JW, et al. J Clin Endocrinol Metab. 2014;99(6):1915-1942.2. National Comprehensive Cancer Network. NCCN clinical practice guidelines in oncology (NCCN Guidelines®). Neuroendocrine and Adrenal Tumors. V1.2022. Accessed June 28, 2022. http://www.nccn.org