Metanephrines

Clinical Chemistry

---

Description

The majority of phaeochromocytomas have unequivocally elevated excretion of both catecholamines and metanephrines, but some tumours are only associated with elevated metanephrines. At the time of writing, current opinion is that plasma metanephrines have a sensitivity of approximately 99%, urinary metanephrines 97%, urinary catecholamines 86% and plasma catecholamines 84%. Specificity is approximately 89% for plasma metanephrines, 88% for urinary catecholamines, 81% for plasma catecholamines and 69% for urinary metanephrines. Suppression of plasma normetanephrine by less than 40% after Clonidine appears to be the best test for phaeochromcotyoma, with a positive predictive value of 100% and a negative predictive value of 96% (suppression of plasma noradrenaline by <50% gives a negative predictive value of only 75%).

---

Sample Type

24 hour urine collected into 2 L bottle with 30 mL 2M sulphuric acid.

---

Reference Range

Reference ranges are provided on the report. Alternatively, please contact the laboratory for current ranges.

---

Turnaround Time

Within 2 weeks

---

Testing Frequency

Weekly.

---

External Notes

Urine metanephrines are now the front line screening test for phaeochromocytoma and paraganglioma. Patients must avoid foods that contain capsaicin e.g. chilli peppers, black pepper, cayenne pepper and bell peppers for 24 hours before and during collection. There is a risk of falsely low results.

---

Please note: the above information is subject to change and we endeavour to keep this website up to date wherever necessary.