Does a Normal Urine Free Cortisol Result Rule out Cushing’s Syndrome?

Posted on August 4, 2015 by MaryO
Endocrine Society’s 97th Annual Meeting and Expo, March 5–8, 2015 – San Diego
SAT-384:
Does a Normal Urine Free Cortisol Result Rule out Cushing’s Syndrome?
Susmeeta T. Sharma1 and Lynnette K Nieman2

  • 1Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD
  • 2National Institutes of Health, Bethesda, MD
Presentation Number: SAT-384
Date of Presentation: March 7, 2015
Abstract:Background: Urine free cortisol (UFC) has been traditionally used as one of the first steps in the diagnostic evaluation of Cushing’s syndrome (CS) (1). False positive results, especially values less than twice the upper limit of normal (ULN), can be seen in uncontrolled diabetes, obesity, depression, alcoholism, increased fluid intake, overcollection and stress. False negative results have also been reported with incomplete collection, in mild or cyclic CS and in patients with renal insufficiency (2-3). We evaluated the diagnostic accuracy of UFC and 24-hour urine 17-hydroxycorticosteroids (17OHCS) in patients with CS.Methods: Retrospective study of all CS patients evaluated at the National Institutes of Health (NIH) from 2009 to 2014. Screening tests used for CS included UFC, 17OHCS, late night salivary cortisol (LNSC), midnight serum cortisol and low dose (1mg overnight or 2-day 2mg/day) dexamethasone suppression test (DST). Values above reference range for UFC, 17OHCS and LNSC, a midnight serum cortisol ≥ 7.5 mcg/dL, and post-dexamethasone cortisol values ≥ 1.8 mcg/dL were considered abnormal. Hourly 24-hour sampling for cortisol was performed in a few cases with a mild clinical phenotype and equivocal test results. UFC was measured using liquid chromatography/tandem mass spectrometry (LC-MS/MS). 17OHCS was measured using colorimetric methodology with Porter-Silber reaction (reported as mg/g of creatinine). Mean of the first two UFC and 17OHCS values (appropriate collection by urine volume and creatinine) obtained within 30 days of initial NIH presentation were used for the purpose of this study.

Results: Seventy-two patients were diagnosed with CS (aged 18-77 years, 51 females). Of these, 51 had Cushing’s disease (CD), 10 had ectopic CS while 2 had an adrenal source of Cushing’s based on pathology. Biochemical tests including inferior petrosal sinus sampling (IPSS) suggested ectopic CS but no tumor was found (occult) in 6 patients. IPSS was indicative of a pituitary source in 2 patients with failed transsphenoidal surgery while one patient did not complete evaluation for ACTH-dependent CS. UFC results were available in all, 17OHCS in 70, LNSC in 21, midnight serum cortisol in 68 and DST results in 37 patients. UFC was falsely normal in six and only minimally elevated (< 2 x ULN) in 13 patients (normal renal function, no history of cyclicity, all had CD). Of these 19 patients, 24h 17OHCS was abnormal in all, LNSC was abnormal in 12, midnight serum cortisol was abnormal in 18 and DST was abnormal in 12 patients. Hourly 24-hour sampling for cortisol performed in 3 of these patients revealed abnormal nadir (> 7.5 mcg/dL) and mean daily serum cortisol (> 9 mcg/dL) levels.

Conclusion: UFC can be falsely normal or only minimally elevated in mild CS. Multiple collections and use of complimentary screening tests including 24-hour urine 17OHCS and LNSC can help make a diagnosis and prevent delay in treatment.

(1) Newell-Price J, et al. Cushing’s syndrome. Lancet. 2006;367(9522):1605-17.  (2) Alexandraki KI, et al. Is urinary free cortisol of value in the diagnosis of Cushing’s syndrome. Curr Opin Endocrinol Diabetes Obes. 2011;18:259–63.  (3) Kidambi S, et al. Limitations of nocturnal salivary cortisol and urine free cortisol in the diagnosis of mild Cushing’s syndrome. Eur J Endocrinol. 2007;157(6):725-31

Nothing to Disclose: STS, LKN

Sources of Research Support: This research was in part supported by the intramural research program of NICHD/NIH

Read the entire article at http://press.endocrine.org/doi/abs/10.1210/endo-meetings.2015.ahpaa.9.sat-384

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Does a normal urine free cortisol result rule out Cushing’s syndrome?

Posted on March 7, 2015 by MaryO

ENDO_2015

 

March 07, 2015

SAT 379-412-Cushing’s Syndrome

Does a normal urine free cortisol result rule out Cushing’s syndrome?

ST Sharma, LK Nieman

Summary: Researchers conducted this study to assess the diagnostic accuarcy of urine free cortisol (UFC) and 24-hour urine 17-hydroxycorticosteroids (170HCS) in patients with Cushing’s syndrome, concluding that in patients with mild CS, UFC can be falsely normal or only minimally elevated. Further, they found that to help in making a diagnosis and prevent treatment delays, clinicians may consider incorporating multiple collections and use of complimentary screening tests including 24-hour urine 17OHCS and late night salivary cortisol (LNSC) testing.

Methods:

  • For this retrospective study, researchers included all CS patients evaluated at the National Institutes of Health (NIH) from 2009 to 2014.
  • The screening tests used for CS included UFC, 17OHCS, midnight serum cortisol and low dose (1 mg overnight or 2-day 2 mg/day) dexamethasone suppression test (DST).
  • They defined abnormal as values above reference range for UFC, 17OHCS and LNSC, a midnight serum cortisol ≥7.5 mcg/dL, and post-dexamethasone cortisol values ≥1.8 mcg/dL.
  • Hourly 24-hour sampling for cortisol was performed in a few cases with a mild clinical phenotype and equivocal test results.
  • Researchers measured UFC using liquid chromatography/tandem mass spectrometry (LC-MS/MS), and 17OHCS was measured using colorimetric methodology with Porter-Silber reaction (reported as mg/g of creatinine).
  • For this study, they used the mean of the first two UFC and 17OHCS values (appropriate collection by urine volume and creatinine) obtained within 30 days of initial NIH presentation.

Results:

  • In all, 72 patients were diagnosed with CS (aged 18-77 years, 51 females), 51 of whom had CD, 10 had ectopic CS, and 2 had an adrenal source of Cushing’s based on pathology.
  • Biochemical tests such as inferior petrosal sinus sampling (IPSS) suggested ectopic CS, but no tumor was found (occult) in 6 patients.
  • In 2 patients with failed transsphenoidal surgery, IPSS was indicative of a pituitary source, and one patient did not complete evaluation for ACTH-dependent CS.
  • UFC results were available in all patients, 17OHCS in 70, LNSC in 21, midnight serum cortisol in 68, and DST results in 37 patients.
  • UFC was falsely normal in 6 patients and only minimally elevated (<2 x ULN) in 13 patients (normal renal function, no history of cyclicity, all had CD); of these 19 patients, 24-hour 17OHCS was abnormal in all, LNSC was abnormal in 12, midnight serum cortisol was abnormal in 18, and DST was abnormal in 12 patients.
  • Hourly 24-hour sampling for cortisol performed in 3 of these patients revealed abnormal nadir (>7.5 mcg/dL) and mean daily serum cortisol (>9 mcg/dL) levels.

From http://www.mdlinx.com/endocrinology/conference-abstract.cfm/ZZ5BA369FDE9DE4CED82CB6A7CD5BFD1BE/42581/?utm_source=confcoveragenl&utm_medium=newsletter&utm_content=abstract-list&utm_campaign=abstract-ENDO2015&nonus=0

Filed under: Clinical trials, Cushing's, Meetings and Conferences, pituitary, Treatments | Tagged: , , , , , , , , , , , | Leave a comment »

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