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Authors’ Response: HPA Axis Testing after Pituitary Surgery

Regional Centre for Endocrinology and Diabetes (C.H.H., A.B.A.), and Regional Endocrine Laboratory (B.S.), Royal Victoria Hospital, Belfast BT12 6BA, Northern Ireland, United Kingdom

Address correspondence to: A. B. Atkinson, Consultant Physician, Royal Victoria Hospital, Grosvenor Road, Belfast BT12 6BA, Northern Ireland, United Kingdom. E-mail: ab.atkinson{at}royalhospitals.n-i.nhs.uk.

To the editor:

We thank Padfield et al. (1) for their interest in our paper and agree that overreliance on arbitrary "pass-fail" cortisol levels undervalues clinical acumen and overvalues the precision of assays. We agree that use of clinical acumen remains important, especially in those patients with results in a borderline range, and indeed we do not regard corticosteroid replacement in such patients as "all or nothing." It is our practice in some cases to instruct such patients to keep a supply of hydrocortisone at home for use during illness but not to take routinely.

Furthermore, the issue of various cut-off levels after standard dose corticotropin administration highlights the tension between test sensitivity and specificity. We feel that the balance should lie in favor of a high sensitivity rather than specificity in excluding ACTH deficiency, so that untreated ACTH deficiency is minimized. Our setting a level of 650 nmol/liter gave 100% sensitivity in excluding ACTH deficiency. This was at the expense of specificity. However, given that inappropriate corticosteroid treatment is likely to be preferred over untreated ACTH deficiency and that the insulin hypoglycemia testing can be used as a back-up to clarify the situation, we feel that this is a preferable situation.

A substantial increase in workload is not anticipated, as in our series, given our criteria, seven of 41 patients would have required an insulin hypoglycemia test to clarify their ACTH status.

Received February 2, 2005.

References

1. Padfield PL, Seckl JR, Walker BR, Gleeson HK 2005 Letter re: HPA axis testing after pituitary surgery. J Clin Endocrinol Metab 90:4981–4982[Free Full Text]

This Article Full Text (PDF) Submit a related Letter to the Editor Purchase Article View Shopping Cart Alert me when this article is cited Alert me when eLetters are posted Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Request Copyright Permission Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Courtney, C. H. Articles by Sheridan, B. Search for Related Content PubMed PubMed Citation Articles by Courtney, C. H. Articles by Sheridan, B. Related Collections Adrenal and Hypertension Neuroendocrinology and Pituitary