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Biochemical detection of phaeochromocytoma: should we still be measuring urinary HMMA?
1Department of Clinical Biochemistry, Freeman Hospital, Newcastle upon Tyne.
Aims:
To compare the diagnostic value of biochemical tests in the detection of phaeochromocytoma.
Methods:
Urinary catecholamines and metabolites were measured by high performance liquid chromatography in the initial 24 hour collections from 31 patients with histologically confirmed phaeochromocytoma. Results were compared with values from 50 patients investigated for the possible presence of a phaeochromocytoma but in whom an alternative diagnosis was later established.
Results:
The diagnostic sensitivity for the measurement of normetadrenaline (NMT) (97%) was greater than any other single factor. Use of a combined noradrenaline and adrenaline value in preference to individual values increased the sensitivity of free catecholamines to 97%. Urinary 4-hydroxy-3-methoxymandelic acid (HMMA) showed a much lower sensitivity for the detection of phaeochromocytoma (81%). An increased excretion of either noradrenaline, adrenaline, or combined catecholamines was found in all 31 patients.
Conclusions:
A combination of biochemical tests improves the detection of phaeochromocytoma. The measurement of urinary free catecholamines or metadrenalines, or both, is better than HMMA estimation. It is recommended that the practice of using only HMMA measurements for the biochemical detection of phaeochromocytoma should be abandoned.