Incidentaloma laboratory findings

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Mohammed Abdelwahed M.D [2]

Overview

Laboratory findings consistent with the diagnosis of incidentaloma include an abnormal 1 mg overnight dexamethasone for subclinical Cushing’s syndrome that should be confirmed with 24-hour urinary free cortisol, serum ACTH concentration, and dehydroepiandrosterone sulfate (DHEAS). In patients with adrenal masses that have a probability for pheochromocytoma, routine measurement of 24-hour urinary fractionated metanephrines and catecholamines should be done. All patients with hypertension and an adrenal incidentaloma should be evaluated by measurements of plasma aldosterone concentration and plasma renin activity.

Laboratory Findings

Subclinical Cushing’s syndrome

Subclinical Cushing’s syndrome should be ruled out by performing the 1 mg overnight dexamethasone suppression test (DST).^[1]^[2]^[3]
An abnormal 1 mg overnight dexamethasone should be confirmed with 24-hour urinary free cortisol, serum ACTH concentration, and dehydroepiandrosterone sulfate (DHEAS).
An undetectable level of serum ACTH is also supportive of the diagnosis of subclinical Cushing’s syndrome.
Hormonal evaluation in the patients with subclinical Cushing’s syndrome showed the following:
- Low baseline secretion of ACTH
- Lack of suppressibility of cortisol secretion after 1 mg dexamethasone
- Supranormal 24-hour urinary cortisol excretion
- Disturbed cortisol circadian rhythm
- Blunted plasma ACTH responses to corticotropin-releasing hormone (CRH)

Pheochromocytoma

In patients with adrenal masses that have a probability for pheochromocytoma, routine measurement of 24-hour urinary fractionated metanephrines and catecholamines should be done.^[4]

Hyperaldosteronism|Aldosteronomas

All patients with hypertension and an adrenal incidentaloma should be evaluated by measurements of plasma aldosterone concentration and plasma renin activity.^[5]^[6]^[7]^[6]
Measurement of plasma aldosterone to renin ratio (ARR) is the best initial test for the evaluation of primary aldosteronism.
A serum aldosterone level below 0.25 nmol/liter (9 ng/dl) makes a diagnosis of primary aldosteronism highly unlikely.
Borderline values should be repeated in below situation:

After correcting hypokalemia,
While the patient is on salt restriction,
In the morning and in a sitting position,
After resting for at least 15 minutes before proceeding with confirmatory tests.

Patients with an elevated ARR should proceed with a confirmatory test such as the salt loading test or saline suppression test.

References

↑ Nieman LK, Biller BM, Findling JW, Newell-Price J, Savage MO, Stewart PM; et al. (2008). “The diagnosis of Cushing’s syndrome: an Endocrine Society Clinical Practice Guideline”. J Clin Endocrinol Metab. 93 (5): 1526–40. doi:10.1210/jc.2008-0125. PMC 2386281. PMID 18334580.
↑ Eller-Vainicher C, Morelli V, Salcuni AS, Torlontano M, Coletti F, Iorio L; et al. (2010). “Post-surgical hypocortisolism after removal of an adrenal incidentaloma: is it predictable by an accurate endocrinological work-up before surgery?”. Eur J Endocrinol. 162 (1): 91–9. doi:10.1530/EJE-09-0775. PMID 19797503.
↑ Katabami T, Obi R, Shirai N, Naito S, Saito N (2005). “Discrepancies in results of low-and high-dose dexamethasone suppression tests for diagnosing preclinical Cushing’s syndrome”. Endocr J. 52 (4): 463–9. PMID 16127216.
↑ Young WF (2007). “Clinical practice. The incidentally discovered adrenal mass”. N Engl J Med. 356 (6): 601–10. doi:10.1056/NEJMcp065470. PMID 17287480.
↑ Mosso L, Carvajal C, González A, Barraza A, Avila F, Montero J; et al. (2003). “Primary aldosteronism and hypertensive disease”. Hypertension. 42 (2): 161–5. doi:10.1161/01.HYP.0000079505.25750.11. PMID 12796282.
↑ ^6.0 ^6.1 Funder JW, Carey RM, Fardella C, Gomez-Sanchez CE, Mantero F, Stowasser M; et al. (2008). “Case detection, diagnosis, and treatment of patients with primary aldosteronism: an endocrine society clinical practice guideline”. J Clin Endocrinol Metab. 93 (9): 3266–81. doi:10.1210/jc.2008-0104. PMID 18552288.
↑ Mitchell IC, Auchus RJ, Juneja K, Chang AY, Holt SA, Snyder WH; et al. (2007). ““Subclinical Cushing’s syndrome” is not subclinical: improvement after adrenalectomy in 9 patients”. Surgery. 142 (6): 900–5, discussion 905.e1. doi:10.1016/j.surg.2007.10.001. PMID 18063074.

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[pmid18334580-1] Nieman LK, Biller BM, Findling JW, Newell-Price J, Savage MO, Stewart PM; et al. (2008). “The diagnosis of Cushing’s syndrome: an Endocrine Society Clinical Practice Guideline”. J Clin Endocrinol Metab. 93 (5): 1526–40. doi:10.1210/jc.2008-0125. PMC 2386281. PMID 18334580.

[pmid19797503-2] Eller-Vainicher C, Morelli V, Salcuni AS, Torlontano M, Coletti F, Iorio L; et al. (2010). “Post-surgical hypocortisolism after removal of an adrenal incidentaloma: is it predictable by an accurate endocrinological work-up before surgery?”. Eur J Endocrinol. 162 (1): 91–9. doi:10.1530/EJE-09-0775. PMID 19797503.

[pmid16127216-3] Katabami T, Obi R, Shirai N, Naito S, Saito N (2005). “Discrepancies in results of low-and high-dose dexamethasone suppression tests for diagnosing preclinical Cushing’s syndrome”. Endocr J. 52 (4): 463–9. PMID 16127216.

[pmid17287480-4] Young WF (2007). “Clinical practice. The incidentally discovered adrenal mass”. N Engl J Med. 356 (6): 601–10. doi:10.1056/NEJMcp065470. PMID 17287480.

[pmid12796282-5] Mosso L, Carvajal C, González A, Barraza A, Avila F, Montero J; et al. (2003). “Primary aldosteronism and hypertensive disease”. Hypertension. 42 (2): 161–5. doi:10.1161/01.HYP.0000079505.25750.11. PMID 12796282.

[pmid185522882-6] 6.0 ^6.1 Funder JW, Carey RM, Fardella C, Gomez-Sanchez CE, Mantero F, Stowasser M; et al. (2008). “Case detection, diagnosis, and treatment of patients with primary aldosteronism: an endocrine society clinical practice guideline”. J Clin Endocrinol Metab. 93 (9): 3266–81. doi:10.1210/jc.2008-0104. PMID 18552288.

[pmid18063074-7] Mitchell IC, Auchus RJ, Juneja K, Chang AY, Holt SA, Snyder WH; et al. (2007). ““Subclinical Cushing’s syndrome” is not subclinical: improvement after adrenalectomy in 9 patients”. Surgery. 142 (6): 900–5, discussion 905.e1. doi:10.1016/j.surg.2007.10.001. PMID 18063074.

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