PSAT031 Dietary Influence (smoothies) on Measurements of Plasma and Urinary Metanephrines in a Patient with Hypertension.

Abstract

Abstract Introduction Pheochromocytoma can be diagnosed by fractionated plasma and urinary metanephrines. However, these tests have several diagnostic issues. Drugs, such as tricyclic antidepressants, and diets both can affect biochemical testing. We report a patient who was consuming a catecholamine rich diet in the form of smoothies which resulted in falsely elevated metanephrines. Case history A 37-year-old female was seen in 2021 for evaluation of secondary hypertension. Patient had a history of intermittent palpitations but denied headaches or excessive sweating. She was taking amlodipine 5mg daily and potassium chloride 20mg daily. Significant past medical history included a partial nephrectomy for renal cell cancer at the age of 35 years. She denies family history of pheochromocytoma or MEN 2. Vital signs showed HR 70/min, BP 138/80 mm Hg. Examination of the heart, lungs and abdomen was normal. Skin exam revealed no bruises or abdominal striae. Labs revealed normal CBC, serum K 3.4, aldosterone 20.1 ng/dL (ref 0.0 - 30.0), renin 1.165 ng/mL/hr (0.167-5.360). Following 1-mg dexamethasone suppression test, serum cortisol was 1.0 mcg/dL. Plasma normetanephrine 113.8 pg/mL (0.0 - 110.1), metanephrine 26.1 pg/mL (0.0 - 88), 24-hour urine metanephrines 465 mg/24hr (74 - 297), normetanephrine 963 mg/24hr (105 - 354). Due to the discordant values between the plasma and urinary metanephrines, a detailed history was taken which revealed that her diets included smoothies, consisting of pineapple juice, bananas, papaya, mango, and sea moss. She drank 15 ounces 3 times per week. Additionally, she was also consuming 1 cup of pistachios and 1 cup of elderberries daily. Patient was counseled to stop drinking the smoothies, and eating pistachios and elderberry. Six weeks later her 24-hour urine metanephrines and normetanephrines returned at 80 mcg/24 hrs and 243 mcg/24 hrs, respectively. Additionally, CT of the adrenal glands confirmed normal adrenal glands. Conclusion Previous studies have shown that catecholamines from dietary sources can dramatically affect plasma as well urinary concentrations of the 3-O methylated metabolites of catecholamines. In our patient, consumption of catecholamine rich foods such as bananas, oranges, pineapples, and possibly elderberry may have contributed to the false positive results. Additionally, the discrepancy between the baseline plasma and urine metanephrines, the normal adrenal glands on CT and normalization of the metanephrines after discontinuing the smoothie diets confirmed that the false positive laboratory values indeed resulted from dietary influence. It is recommended that a detailed dietary history be taken prior to ordering laboratory testing for catecholamine-secreting tumors. Possible interfering medications and catecholamine rich foods should be discontinued, if possible, before biochemical testing to avoid false positive results. Presentation: Saturday, June 11, 2022 1:00 p.m. - 3:00 p.m.