Clinical Endocrinology (2014) 81, 629–632
LETTERS TO THE EDITOR
Spironolactone interference in the immunoassay of androstenedione in a patient with a cortisol secreting adrenal adenoma Sir, In the assessment of patients with secondary hypertension and an adrenal lesion, the endocrinologist seeks to establish what adrenal hormones are implicated in the patient’s increased blood pressure and whether the lesion could be malignant (adrenocortical carcinoma).1 Hypersecretion of steroids from two zones of the adrenal cortex is unusual in benign adrenal disease and may indicate that the lesion is an adrenocortical carcinoma.1 Such hormonal hypersecretion is not always clinically apparent2; therefore, the managing physician is dependent upon measurement of steroid hormones by nonisotopic immunoassay or sometimes by radioimmunoassay (RIA). Steroid hormones share multiple structural similarities; cross-reaction of the RIA antibodies with other hormones is recognized but often dismissed as of little clinical significance. We present a case in which spironolactone interfered with androstenedione measurement, the result of which changed risk stratification for malignancy. A 48-year-old man was referred from Cardiology for investigation of hypokalaemic hypertension in association with an adrenal mass. At presentation, his blood pressure was 180/ 100 mmHg while taking olmesartan 20 mg, hydrochlorothiazide 25 mg, felodipine 5 mg and spironolactone 25 mg daily. Echocardiography revealed left ventricular hypertrophy. Serum potassium was 33 mM. Noncontrast CT demonstrated a 33 cm mass in the right adrenal gland with a mean attenuation of 26 Hounsfield units (HU) (Fig. 1). Endocrine investigations revealed increased plasma androstenedione (199, reference range 28– 105 nM), using the Direct Androstenedione Coat-a-Count radioimmunoassay method (Siemens Healthcare, Camberley, Surrey, UK). Plasma cortisol concentration (DPC Immulite 2000 System; Siemens Healthcare) at 0900 h was not suppressed at 159 nM after a 1 mg overnight dexamethasone suppression test (normal < 50 nM). Hypercortisolaemia was confirmed with a 48-h low-dose dexamethasone suppression test; cortisol was 263 nM (normal < 50 nM). Plasma ACTH concentration before dexamethasone was undetectable. Three 24-h urine collections for catecholamines and metanephrines, performed to exclude pheochromocytoma, were normal. The finding of increased androstenedione coupled with Hounsfield units of 26 on imaging raised concerns that this gentleman had an adrenocortical carcinoma with hypersecretion across two zones of the adrenal cortex (zona fasciculata and reticularis). However, spironolactone, hydrochlorothiazide and olmesartan were discontinued for assessment of renin–angiotensin–aldosterone system, and 6 weeks later he underwent re-assessment, at which time androstenedione measured 37 nM, and there was no evidence of primary hyperaldosteronism. This suggested that the initial © 2013 John Wiley & Sons Ltd
Fig. 1 CT abdomen demonstrating 33 cm right-sided adrenal adenoma (white arrow) and contralateral gland (black arrow).
result represented assay interference. The patient underwent laparoscopic adrenalectomy with postoperative glucocorticoid cover. Histological examination of the excised adrenal yielded a Weiss score of 0/9. Six weeks after surgery he underwent a short synacthen test (250 lg of Synacthenâ; Alliance Pharmaceuticals, Chippenham, Wiltshire, UK) with a 30-min cortisol response of 366 nM (normal > 550 nM). The patient remains on oral glucocorticoid replacement therapy and will undergo serial re-assessment of the hypothalamic–pituitary adrenal axis. In this case, hypercortisolaemia with undetectable ACTH suggested Cushing’s syndrome of adrenal origin. The possibility of 629
630 Letters to the Editor an underlying ACC was considered because of the imaging characteristics of this gentleman’s adrenal lesion (size >3 cm and attenuation >20 HU)2,3 and because there was evidence of hypersecretion of hormones from two zones of the adrenal cortex. In a recent series of 45 carcinomas compared with 102 adenomas, 12 ACC patients had combined hypersecretion of glucocorticoids and androgens; no patient with benign disease had dual secretion with this combination.1 After spironolactone was withheld, androstenedione levels were normal, which reduced the pre-operative likelihood that the lesion was malignant. It was concluded that spironolactone had interfered with the measurement of androstenedione using the Direct Androstenedione Coat-A-Count (CAC) radioimmunoassay (Siemens Healthcare). There has been one previous report of spironolactone interference with androstenedione measurement by the CAC assay, in a polycystic ovary syndrome (PCOS) patient group treated with 100–200 mg/day spironolactone4, but such interference has never been reported in a patient with hypercortisolaemia or an adrenal lesion, in which diagnosis, prognostication and management would be affected by the result, as we have discussed. In the PCOS group previously reported, three patients had CAC-measured serum androstenedione concentrations on spironolactone therapy that were fourfold higher than the levels measured by the Immulite assay (Siemens). The authors speculated that the androstenedione antibodies in the assay could be reacting with the C/D ring or 7-modified thiol residue of spironolactone or its metabolites.4 The patient was receiving a low dose of spironolactone, but it is apparent that the dose was sufficient to cause interference because serum androstenedione normalized after withdrawal. The manufacturer suggests that the cross-reaction of spironolactone with androstenedione in this assay is 0109%; this implies that our patient’s blood spironolactone concentration would have to have been greater than 4000 ng/ml to give this androstenedione result through interference. The manufacturer of spironolactone quotes a peak plasma concentration of spironolactone of 80 ng/ml, its 7-alpha-(thiomethyl) spironolactone metabolite of 391 ng/ml and its canrenone metabolite of 181 ng/ml, and even levels of this magnitude are unlikely to have been achieved on a dose of 25 mg spironolactone. Clearly, the cross-reactivity of spironolactone with the androstenedione assay in this patient was higher than that quoted by the manufacturer. Liquid chromatography–mass spectrometry is the preferred method for measurement of steroids because it offers improved specificity over immunoassay. Spironolactone does not interfere in a tandem MS assay for androstenedione because of their different molecular weights (416 compared to 286). It is important that endocrinologists are aware of the limitations of their local assay; use LCMS for androstenedione measurement if available; and if LCMS is not locally available, it would be preferable to send samples for androstenedione analysis to a laboratory with this technology. Where cross-reaction of medications with immunoassays is not recognized there is potential for impact upon patient management.
Conflict of interest The authors have no conflict of interest or financial disclosure to declare. Rachel K. Crowley*, Deirdre Broderick*, Triona O’Shea*, Gerard Boran†, Vincent Maher‡, Stephen Crowther§, James Gibney*, Kevin C. Conlon¶ and Mark Sherlock* *Departments of Endocrinology, †Chemical Pathology, ‡Cardiology, §Cellular Pathology, and ¶Professorial Surgical Unit, Tallaght Hospital, Dublin, Ireland E-mail: [email protected] The patient reviewed the manuscript and gave permission for publication.
doi: 10.1111/cen.12372
References 1 Arlt, W., Biehl, M., Taylor, A.E. et al. (2011) Urine steroid metabolomics as a biomarker tool for detecting malignancy in adrenal tumors. Journal of Clinical Endocrinology and Metabolism, 96, 3775–3784. 2 Zeiger, M.A., Siegelman, S.S. & Hamrahian, A.H. (2011) Medical and surgical evaluation and treatment of adrenal incidentalomas. Journal of Clinical Endocrinology and Metabolism, 96, 2004–2015. 3 Hamrahian, A.H., Ioachimescu, A.G., Remer, E.M. et al. (2005) Clinical utility of noncontrast computed tomography attenuation value (hounsfield units) to differentiate adrenal adenomas/hyperplasias from nonadenomas: Cleveland Clinic experience. Journal of Clinical Endocrinology and Metabolism, 90, 871–877. 4 Honour, J.W., Tsilchorozidou, T., Conway, G.S. et al. (2010) Spironolactone interference in the immunoassay of androstenedione. Annals of Clinical Biochemistry, 47, 564–566.
Noninvasive encapsulated follicular variant of papillary thyroid carcinoma: is lobectomy sufficient for tumours ≥1 cm? Dear Editor, Some authors have shown that the encapsulated follicular variant of papillary thyroid carcinoma (E-FVPTC) has a better prognosis than encapsulated classic PTC1,2 and nonencapsulated FVPTC.3,4 In patients with PTC restricted to the gland (i.e. without extrathyroid invasion or apparent metastases), lobectomy is considered sufficient for unifocal tumours ≤1 cm, whereas total thyroidectomy followed by 131I ablation is recommended for tumours >4 cm.5 In the case of tumours >1 cm and ≤4 cm, more aggressive initial therapy should be considered in the presence of vascular invasion.5 Therefore, doubts remain regarding the treatment of intrathyroid PTC when the tumour measures 1–4 cm and does not exhibit vascular invasion. As the hypothesis is that E-FVPTC is more indolent, it is important to know
© 2013 John Wiley & Sons Ltd Clinical Endocrinology (2014), 81, 629–632
LETTERS TO THE EDITOR
Spironolactone interference in the immunoassay of androstenedione in a patient with a cortisol secreting adrenal adenoma Sir, In the assessment of patients with secondary hypertension and an adrenal lesion, the endocrinologist seeks to establish what adrenal hormones are implicated in the patient’s increased blood pressure and whether the lesion could be malignant (adrenocortical carcinoma).1 Hypersecretion of steroids from two zones of the adrenal cortex is unusual in benign adrenal disease and may indicate that the lesion is an adrenocortical carcinoma.1 Such hormonal hypersecretion is not always clinically apparent2; therefore, the managing physician is dependent upon measurement of steroid hormones by nonisotopic immunoassay or sometimes by radioimmunoassay (RIA). Steroid hormones share multiple structural similarities; cross-reaction of the RIA antibodies with other hormones is recognized but often dismissed as of little clinical significance. We present a case in which spironolactone interfered with androstenedione measurement, the result of which changed risk stratification for malignancy. A 48-year-old man was referred from Cardiology for investigation of hypokalaemic hypertension in association with an adrenal mass. At presentation, his blood pressure was 180/ 100 mmHg while taking olmesartan 20 mg, hydrochlorothiazide 25 mg, felodipine 5 mg and spironolactone 25 mg daily. Echocardiography revealed left ventricular hypertrophy. Serum potassium was 33 mM. Noncontrast CT demonstrated a 33 cm mass in the right adrenal gland with a mean attenuation of 26 Hounsfield units (HU) (Fig. 1). Endocrine investigations revealed increased plasma androstenedione (199, reference range 28– 105 nM), using the Direct Androstenedione Coat-a-Count radioimmunoassay method (Siemens Healthcare, Camberley, Surrey, UK). Plasma cortisol concentration (DPC Immulite 2000 System; Siemens Healthcare) at 0900 h was not suppressed at 159 nM after a 1 mg overnight dexamethasone suppression test (normal < 50 nM). Hypercortisolaemia was confirmed with a 48-h low-dose dexamethasone suppression test; cortisol was 263 nM (normal < 50 nM). Plasma ACTH concentration before dexamethasone was undetectable. Three 24-h urine collections for catecholamines and metanephrines, performed to exclude pheochromocytoma, were normal. The finding of increased androstenedione coupled with Hounsfield units of 26 on imaging raised concerns that this gentleman had an adrenocortical carcinoma with hypersecretion across two zones of the adrenal cortex (zona fasciculata and reticularis). However, spironolactone, hydrochlorothiazide and olmesartan were discontinued for assessment of renin–angiotensin–aldosterone system, and 6 weeks later he underwent re-assessment, at which time androstenedione measured 37 nM, and there was no evidence of primary hyperaldosteronism. This suggested that the initial © 2013 John Wiley & Sons Ltd
Fig. 1 CT abdomen demonstrating 33 cm right-sided adrenal adenoma (white arrow) and contralateral gland (black arrow).
result represented assay interference. The patient underwent laparoscopic adrenalectomy with postoperative glucocorticoid cover. Histological examination of the excised adrenal yielded a Weiss score of 0/9. Six weeks after surgery he underwent a short synacthen test (250 lg of Synacthenâ; Alliance Pharmaceuticals, Chippenham, Wiltshire, UK) with a 30-min cortisol response of 366 nM (normal > 550 nM). The patient remains on oral glucocorticoid replacement therapy and will undergo serial re-assessment of the hypothalamic–pituitary adrenal axis. In this case, hypercortisolaemia with undetectable ACTH suggested Cushing’s syndrome of adrenal origin. The possibility of 629
630 Letters to the Editor an underlying ACC was considered because of the imaging characteristics of this gentleman’s adrenal lesion (size >3 cm and attenuation >20 HU)2,3 and because there was evidence of hypersecretion of hormones from two zones of the adrenal cortex. In a recent series of 45 carcinomas compared with 102 adenomas, 12 ACC patients had combined hypersecretion of glucocorticoids and androgens; no patient with benign disease had dual secretion with this combination.1 After spironolactone was withheld, androstenedione levels were normal, which reduced the pre-operative likelihood that the lesion was malignant. It was concluded that spironolactone had interfered with the measurement of androstenedione using the Direct Androstenedione Coat-A-Count (CAC) radioimmunoassay (Siemens Healthcare). There has been one previous report of spironolactone interference with androstenedione measurement by the CAC assay, in a polycystic ovary syndrome (PCOS) patient group treated with 100–200 mg/day spironolactone4, but such interference has never been reported in a patient with hypercortisolaemia or an adrenal lesion, in which diagnosis, prognostication and management would be affected by the result, as we have discussed. In the PCOS group previously reported, three patients had CAC-measured serum androstenedione concentrations on spironolactone therapy that were fourfold higher than the levels measured by the Immulite assay (Siemens). The authors speculated that the androstenedione antibodies in the assay could be reacting with the C/D ring or 7-modified thiol residue of spironolactone or its metabolites.4 The patient was receiving a low dose of spironolactone, but it is apparent that the dose was sufficient to cause interference because serum androstenedione normalized after withdrawal. The manufacturer suggests that the cross-reaction of spironolactone with androstenedione in this assay is 0109%; this implies that our patient’s blood spironolactone concentration would have to have been greater than 4000 ng/ml to give this androstenedione result through interference. The manufacturer of spironolactone quotes a peak plasma concentration of spironolactone of 80 ng/ml, its 7-alpha-(thiomethyl) spironolactone metabolite of 391 ng/ml and its canrenone metabolite of 181 ng/ml, and even levels of this magnitude are unlikely to have been achieved on a dose of 25 mg spironolactone. Clearly, the cross-reactivity of spironolactone with the androstenedione assay in this patient was higher than that quoted by the manufacturer. Liquid chromatography–mass spectrometry is the preferred method for measurement of steroids because it offers improved specificity over immunoassay. Spironolactone does not interfere in a tandem MS assay for androstenedione because of their different molecular weights (416 compared to 286). It is important that endocrinologists are aware of the limitations of their local assay; use LCMS for androstenedione measurement if available; and if LCMS is not locally available, it would be preferable to send samples for androstenedione analysis to a laboratory with this technology. Where cross-reaction of medications with immunoassays is not recognized there is potential for impact upon patient management.
Conflict of interest The authors have no conflict of interest or financial disclosure to declare. Rachel K. Crowley*, Deirdre Broderick*, Triona O’Shea*, Gerard Boran†, Vincent Maher‡, Stephen Crowther§, James Gibney*, Kevin C. Conlon¶ and Mark Sherlock* *Departments of Endocrinology, †Chemical Pathology, ‡Cardiology, §Cellular Pathology, and ¶Professorial Surgical Unit, Tallaght Hospital, Dublin, Ireland E-mail: [email protected] The patient reviewed the manuscript and gave permission for publication.
doi: 10.1111/cen.12372
References 1 Arlt, W., Biehl, M., Taylor, A.E. et al. (2011) Urine steroid metabolomics as a biomarker tool for detecting malignancy in adrenal tumors. Journal of Clinical Endocrinology and Metabolism, 96, 3775–3784. 2 Zeiger, M.A., Siegelman, S.S. & Hamrahian, A.H. (2011) Medical and surgical evaluation and treatment of adrenal incidentalomas. Journal of Clinical Endocrinology and Metabolism, 96, 2004–2015. 3 Hamrahian, A.H., Ioachimescu, A.G., Remer, E.M. et al. (2005) Clinical utility of noncontrast computed tomography attenuation value (hounsfield units) to differentiate adrenal adenomas/hyperplasias from nonadenomas: Cleveland Clinic experience. Journal of Clinical Endocrinology and Metabolism, 90, 871–877. 4 Honour, J.W., Tsilchorozidou, T., Conway, G.S. et al. (2010) Spironolactone interference in the immunoassay of androstenedione. Annals of Clinical Biochemistry, 47, 564–566.
Noninvasive encapsulated follicular variant of papillary thyroid carcinoma: is lobectomy sufficient for tumours ≥1 cm? Dear Editor, Some authors have shown that the encapsulated follicular variant of papillary thyroid carcinoma (E-FVPTC) has a better prognosis than encapsulated classic PTC1,2 and nonencapsulated FVPTC.3,4 In patients with PTC restricted to the gland (i.e. without extrathyroid invasion or apparent metastases), lobectomy is considered sufficient for unifocal tumours ≤1 cm, whereas total thyroidectomy followed by 131I ablation is recommended for tumours >4 cm.5 In the case of tumours >1 cm and ≤4 cm, more aggressive initial therapy should be considered in the presence of vascular invasion.5 Therefore, doubts remain regarding the treatment of intrathyroid PTC when the tumour measures 1–4 cm and does not exhibit vascular invasion. As the hypothesis is that E-FVPTC is more indolent, it is important to know
© 2013 John Wiley & Sons Ltd Clinical Endocrinology (2014), 81, 629–632
