Endocrine Abstracts

Introduction: Due to the frequent occurrence of adrenal incidentalomas, diagnosis of their hormonal activity is a significant clinical concern. Approximately 7-10% of adrenal tumors are pheochromocytomas, which even in silent form can lead to hemodynamic instability during surgery. According to the ESE and ENSAT guidelines in any case of adrenal tumors greater than 1 cm pheochromocytoma should be excluded based on plasma metanephrines level and urinary metanephrines excretion. Such approach can be challenging in patients with significant comorbidities or when patients are on drug which interfere with analytical measurement.

Aim of the study: The aim of this study was to evaluate the effect of selected drug on metanephrines excretion in urine in patients with incidentaloma.

Materials: 1,102 patients with incidentalomas confirmed by CT or MR were included in the study. Patients with a clinical or biochemical diagnosis of Cushing’s or Conn syndrome as well as patients very likely having pheochromocytoma were excluded. In all patients, 24-hour urinary excretion of normetanephrine, metanephrine and 3-methoxytyramine were measured by high performance liquid chromatography (HPLC) with electrochemical detection. The information on concomitant medication (β-blockers, Ca-blockers, loop diuretics, thiazide diuretics, potassium-sparing diuretics, α-blockers, ACE inhibitors/aniotensin II receptor antagonists, metformin, other antidiabetic drugs, lipid lowering drugs, proton pump inhibitors, levothyroxines, thyreostatics, antidepressants, neuroleptics, benzodiazepines, glucocorticosteroids, B receptor agonists and M-receptor antagonists) from each patient were collected.

Results: The analysis showed that urine excretion of normetanephrine was significantly higher in patients (without medication vs medication) using β-blockers (288.9 vs 332.3 μg/24 h, P<0.0001), Ca-blockers (282.6 vs 333.8 μg/24 h, P<0.0001), loop diuretics (299.4 vs 374.5 μg/24 h, P<0.0001), α-blockers (299.3 vs 352.7 μg/24 h, P=0.0001), non-metformin antidiabetic drugs (301.0 vs 366.15 μg/24 h, P=0.0001) and neuroleptics (305.4 vs 384.3 μg/24 h, P=0.0307). Urinary metanephrine excretion was higher in patients taking α-blockers (109.2 vs 136,9 μg/24 h, P<0.0001) and was lower in patients taking non-metformin antidiabetic drugs (114.3 vs 99.3 μg/24 h, P=0.0247), antidepressants (114.3 vs 97.7=8 μg/24 h, P=0.0207) and glucocorticosteroids (114.6 vs 94.8 μg/24 h, P=0.0043). Urinary 3-methoxytyramine concentration was higher in patients taking thiazide diuretics (191.8 vs 264.5 μg/24 h, P=0.0031), antidepressants (195.2 vs 317.9 μg/24 h, P=0.0005) and M-receptor antagonists (198.3 vs 284.6 μg/24 h, P=0.0292). The other drugs had no significant effect on the results of urinary excretion of catecholamines.

Conclusion: Many of the commonly used drug groups significantly affect the results of 24-hour urine collection of fractionated methanephrines. Interpretation of these results should be adjusted and take into account the effect of the drug groups used on the results obtained and individualized in the clinical context.