Can a random serum cortisol reduce the need for short synacthen tests in acute medical admissions?

The use of baseline cortisol level in predicting the outcome of 1 μg Synacthen tests in an outpatient endocrinology unit

Introduction

The clinical requirements and the indication of the Synacthen test are increasing. The objective of our study is to determine a baseline cortisol level that reliably predicts the response to Synacthen test in a low-risk group of patients.

Materials and methods

We performed a cross-sectional analysis of all Synacthen tests conducted between January 2017 and June 2018. The diagnostic accuracy of basal cortisol levels as a predictor of an adequate response to Synacthen test was evaluated by ROC curve analysis.

Results

One hundred and fifty-three patients were included. A baseline cortisol level <40 ng/mL had a sensitivity of 100% but a specificity of 5.8% for the failure of the Synacthen test, while a baseline cortisol level> 147.5 ng/mL showed a specificity of 100% but a sensitivity of 1.2% for an adequate response to the Synacthen test. According to the ROC curve, the optimal baseline cortisol level for predicting an adequate response to the Synacthen test was 85 ng/mL with an AUC of 0.808 (95% CI [0.738–0.877]).

Conclusion

We propose a basal cortisol level assay as a first step in the evaluation of patients with suspected adrenal insufficiency.

Pre-test Cortisol Levels in Predicting Short Synacthen Test Outcome: A Retrospective Analysis

Objective:

Short Synacthen tests (SSTs) are expensive, dependent on Synacthen availability, and need supervision. To reduce SST testing, we examined the utility of pre-test cortisol (Cort0) and related parameters in predicting outcome.

Design and Measurements:

We retrospectively examined the following in all SSTs; (i) Cort0 (ii) indications (iii) and time and place of testing. Receiver operated characteristic (ROC) curves were devised for Cort0 to obtain the best cut-off for outcome prediction in those who had SSTs between 8 and 10 am (Group 1) and at other times (Group 2).

Results:

Of 506 SSTs, 13 were unsuitable for analysis. 111/493 SSTs (22.5%) were abnormal. (1) ROC curves predicted – (a) SST failure with 100% specificity when Cort0 was ⩽124 nmol/L (Group 1), or ⩽47 (Group 2); (b) a normal SST with 100% sensitivity when Cort0 ⩾314 nmol/L (Group 1) and ⩾323 nmol/L (Group 2). (2) There was significant correlation between Cort0 and 30-minute cortisol (r_s = 0.65-0.78, P  < .001). (3) Median Cort0 was lower in those who failed SSTs compared to those who passed (147 vs 298 nmol/L respectively, P  < .001). (4) SST failure was commoner in Group 1 vs 2 (P = .001). (5) There was no difference in outcome between out-patient and inpatient SSTs. (6) SST failure was most common for ‘steroid related’ indications (39.6%, P  < .001).

Conclusions:

This study indicates that (1) Cort0 ⩾ 323 (Group1) and ⩾314 nmol/L (Group 2) predicted a normal SST with 100% sensitivity; (2) Using these cut offs 141/493 (28.6%) tests may have been avoided; (3) supporting evidence should be considered in those with a lower pre-test predictability of failure.

Improving the Interpretation of Afternoon Cortisol Levels and SSTs to Prevent Misdiagnosis of Adrenal Insufficiency

BACKGROUND

Adrenal Insufficiency (AI), especially iatrogenic-AI, is a treatable cause of mortality. The difficulty in obtaining 9 am cortisol levels means samples are taken at suboptimal times, including a substantial proportion in the afternoon. Low afternoon cortisol levels often provoke short Synacthen tests (SSTs). It is important that this does not lead to patients misdiagnosed with AI, exposing them to the excess mortality and morbidity of inappropriate steroid replacement therapy.

METHODS

This retrospective study collected 60 178 cortisol results. Medical records, including subsequent SSTs of initial cortisol results measured after midday were reviewed.

RESULTS

Receiver operating characteristic analysis (area under the curve: 0.89) on 6531 suitable cortisol values showed that a limit of <201.5 nmol/L achieved a sensitivity and specificity of 95.6% and 72.6%, while a limit of <234 nmol/L had a sensitivity of 100% and a specificity of 59.5%. Out of 670 SSTs, 628 patients passed. Of these, 140 would have otherwise failed if only their 30-min cortisol was assessed without the 60-min value. A 30- and 60-min SST cortisol cutoff of 366.5 nmol/L and 418.5 nmol/L, respectively, can achieve a sensitivity of >95% on the Abbott analyser platform.

CONCLUSION

An afternoon cortisol >234 nmol/L excludes AI on Abbott analyser platforms. In patients who have an afternoon cortisol <234 nmol/L, including both 30- and 60-min SST cortisol values prevents unnecessary glucocorticoid replacement therapy in 22.3% of individuals in this study. The Abbott analyser SST cortisol cutoffs used to define AI should be 366.5 nmol/L and 418.5 nmol/L at 30 and 60 min, respectively. All patients remained well subsequently with at least 1-year longitudinal follow-up.

Validated criteria for the interpretation of a single measurement of serum cortisol in the investigation of suspected adrenal insufficiency

OBJECTIVE

The diagnostic value of a single measurement of serum cortisol as a first step in the investigation of suspected adrenal insufficiency remains unclear. Previously proposed criteria have not been validated, and little is known regarding the performance of the test outwith morning samples in outpatients. We aimed to identify and validate criteria for morning and afternoon serum cortisol which could be used to determine which individuals require dynamic testing, in both outpatient and medical inpatient settings.

METHODS

We performed a retrospective analysis of 2768 patients attending endocrinology clinics and patients admitted to general medical units in two hospitals in Edinburgh, UK. In baseline samples from the short synacthen test, thresholds which identified a subnormal-stimulated serum cortisol (<430 nmol/L using the Abbott Architect assay) with 95% sensitivity were identified. Criteria drawn from data in patients attending outpatient clinics in one hospital were tested in additional outpatient and inpatient validation cohorts.

RESULTS

A morning (8 am-12 pm) serum cortisol of <275 nmol/L identified subnormal-stimulated cortisol with 96.2% sensitivity. For afternoon (12 pm-6 pm) samples, a cut-off of <250 nmol/L achieved 96.1% sensitivity. Sensitivity was maintained when the criteria were applied to outpatients in the validation cohort for both morning and afternoon samples. For inpatients, the test was sufficiently sensitive in morning samples only.

CONCLUSIONS

A single measurement of serum cortisol carries the potential to significantly reduce the need for dynamic testing in the investigation of adrenal insufficiency, whether this is taken in morning or afternoon outpatient clinics, or in morning samples from medical inpatients.

Retention of aberrant cortisol secretion in a patient with bilateral macronodular adrenal hyperplasia after unilateral adrenalectomy

Aberrant cortisol secretion responses after exogenous stimuli such as upright posture, eating a mixed meal or receiving agents influencing aberrant G-protein-coupled receptors in adrenal glands, are often observed in patients with bilateral macronodular adrenal hyperplasia (BMAH). However, little is known about whether this aberrant response is retained after unilateral adrenalectomy. Here, we describe a 61-year-old postmenopausal Japanese woman with unsatisfactorily controlled hypertension who was referred to us for further investigation due to her pre-obesity characteristics (body mass index 28.4 kg/m²). Cushing’s signs and serum cortisol at 16.2 µg/dL with undetectable adrenocorticotropic hormone indicated adrenal Cushing’s syndrome. Adrenal imaging revealed bilaterally enlarged adrenal glands with 131-I adosterol uptake; hence, BMAH was diagnosed. Preoperatively, in vivo screening for aberrant adrenal receptors revealed an aberrant response of cortisol secretion on metoclopramide challenge. The patient underwent unilateral adrenalectomy; thereafter, glucocorticoid replacement therapy was reduced to hydrocortisone 15 mg/day at postoperative day 6. Fasting morning serum cortisol level measured at postoperative day 8 was 2.96 µg/dL, suggesting adrenal insufficiency. However, following metoclopramide administration serum cortisol level rose to 19.7 µg/dL, indicating potential efficient adrenal function. Aberrant cortisol secretory capacity was thus preserved in BMAH, even in a state of adrenal insufficiency after unilateral adrenalectomy. Caution should be exercised when assessing the hypothalamus-pituitary-adrenal axis, because in this patient, a high cortisol level did not guarantee appropriate adrenal function when the patient was challenged by exogenous stimuli.

A time-adjusted cortisol cut-off can reduce referral rate for Synacthen stimulation test whilst maintaining diagnostic performance

OBJECTIVE

Cortisol cut-offs can predict requirement for Synacthen stimulation tests (SST). We assessed the performance of a standard cortisol cut-off (375 nmol/L) across the morning and compared this with a time-adjusted cut-off.

DESIGN

Retrospective audit PATIENTS: Community reference set (n=12 550) and SST patients (n=757).

MEASUREMENTS

In the reference population, time-specific cortisol medians were calculated and used to convert cortisol to time-adjusted Multiples of the Median (MoM). In 757 SST patients, the predictive performance of a standard cortisol cut-off (375 nmol/L) and its time-adjusted MoM equivalent were compared.

RESULTS

Median cortisol decreased by ~30 nmol/L per hour between 0700 and 1200h. In the reference population, proportions below the 375 nmol/L cut-off increased throughout the morning (range 35%-64%), whereas using the time-adjusted MoM cut-off proportions were consistent (range 46%-50%), with a 17% maximal difference in referral rates between the two cut-offs after 1100h. A similar pattern was noted in the SST cohort. When a cortisol MoM cut-off was used to predict SST success, the excess proportion of patients tested and misclassification rates were lower and more consistent than when the standard cut-off was used. A median cortisol of 375 nmol/L equated to 444 and 313 nmol/L before 0800 and after 1100 h, respectively.

CONCLUSION

The use of a standard cortisol cut-off results in 17% more patients being referred for SST later in the morning. A time-adjusted cortisol cut-off provides consistent and lower referral rates, whilst maintaining similar or better performance than a standard single cut-off in predicting outcome of SST.

Mineralocorticoid responsive hyponatremia of the elderly: A systematic review

BACKGROUND

Mineralocorticoid responsive hyponatremia of the elderly (MRHE) is an emerging concept of hyponatremia in aged people. Diagnosis of MRHE requires exclusion of syndrome of inappropriate antidiuresis and adrenal dysfunction. Thus we aimed to evaluate the characteristics of all patients with suspected MRHE available for a review.

METHODS

We conducted a systematic review using MEDLINE and Google scholar. We included published case reports of adult patients diagnosed as MRHE, written by English and Japanese language. Serum and urine electrolytes as well as the levels of antidiuretic hormone (ADH), cortisol, plasma renin activity (PRA), and aldosterone were analyzed.

RESULTS

A total of 27 MRHE patients were identified in 9 reports. In these patients, average age was 79 years, median serum sodium was 117 mEq/L. The median levels of ADH, cortisol, PRA, and aldosterone were 0.9 pg/mL, 18.7 μg/dL, 0.37 ng/mL/h, and 39.6 pg/mL, respectively. Water restriction test was conducted in 7 patients. Random sample cortisol measurements did not exceed satisfactory levels to rule out adrenal dysfunction in four cases. No cases underwent low-dose adrenocorticotropic hormone stimulation test. Only 27 patients from 9 case reports in Japanese were eligible for inclusion in our study.

CONCLUSION

All published cases of MRHE as a cause of hyponatremia are described for the first time. In these cases, latent adrenal sufficiency might have been hidden and should have been excluded.

Baseline morning cortisol level as a predictor of pituitary-adrenal reserve: a comparison across three assays

CONTEXT

The short ACTH stimulation test (250 μg) is the dynamic test most frequently used to assess adrenal function. It is possible that a single basal cortisol could be used to predict the dynamic response, but research has been hampered by the use of different assays and thresholds.

OBJECTIVE

To propose a morning baseline cortisol criterion of three of the most commonly used modern cortisol immunoassays - Advia Centaur (Siemens), Architect (Abbott) and the Roche Modular System (Roche) - that could predict adrenal sufficiency.

DESIGN

Observational, retrospective cross-sectional study at two centres.

PATIENTS AND MEASUREMENTS

Retrospective analysis of the results of 1019 Short Synacthen tests (SSTs) with the Advia Centaur, 449 SSTs with the Architect and 2050 SSTs with the Roche Modular System assay. Serum cortisol levels were measured prior to injection of 250 μg Synacthen and after 30 min. Overall, we were able to collate data from a total of 3518 SSTs in 3571 patients.

RESULTS

Using receiver-operator curve analysis, baseline cortisol levels for predicting passing the SST with 100% specificity were 358 nmol/l for Siemens, 336 nmol/l for Abbott and 506 nmol/l for Roche. Utilizing these criteria, 589, 158 and 578 SSTs, respectively, for Siemens, Abbott and Roche immunoassays could have been avoided.

CONCLUSIONS

We have defined assay-specific morning cortisol levels that are able to predict the integrity of the hypothalamo-pituitary-adrenal axis. We propose that this represents a valid tool for the initial assessment of adrenal function and has the potential to obviate the need for dynamic testing in a significant number of patients.

First presentation of Addison's disease as hyperkalaemia in acute kidney injury

Addison's disease is a rare endocrine disorder that frequently presents with non-specific symptoms, but may deteriorate rapidly into life-threatening Addisonian crisis if left untreated. Diagnosis can be difficult in patients without a suggestive medical history. We describe a case of a 37-year-old man who was admitted with acute kidney injury and hyperkalaemia, resistant to treatment with insulin/dextrose and calcium gluconate. On clinical examination, he was found to be hyperpigmented; a subsequent random serum cortisol of 49 nmol/L affirmed the preliminary diagnosis of Addison's disease. The patient's hyperkalaemia improved on treatment with hydrocortisone, and a follow-up morning adrenocorticotropic hormone of 1051 ng/L confirmed the diagnosis.

Adrenal suppression in patients taking inhaled glucocorticoids is highly prevalent and management can be guided by morning cortisol

CONTEXT

Up to 3% of US and UK populations are prescribed glucocorticoids (GC). Suppression of the hypothalamo-pituitary-adrenal axis with the potential risk of adrenal crisis is a recognized complication of therapy. The 250 μg short Synacthen stimulation test (SST) is the most commonly used dynamic assessment to diagnose adrenal insufficiency. There are challenges to the use of the SST in routine clinical practice, including both the staff and time constraints and a significant recent increase in Synacthen cost.

METHODS

We performed a retrospective analysis to determine the prevalence of adrenal suppression due to prescribed GCs and the utility of a morning serum cortisol for rapid assessment of adrenal reserve in the routine clinical setting.

RESULTS

In total, 2773 patients underwent 3603 SSTs in a large secondary/tertiary centre between 2008 and 2013 and 17.9% (n=496) failed the SST. Of 404 patients taking oral, topical, intranasal or inhaled GC therapy for non-endocrine conditions, 33.2% (n=134) had a subnormal SST response. In patients taking inhaled GCs without additional GC therapy, 20.5% (34/166) failed an SST and suppression of adrenal function increased in a dose-dependent fashion. Using receiver operating characteristic curve analysis in patients currently taking inhaled GCs, a basal cortisol ≥348 nmol/l provided 100% specificity for passing the SST; a cortisol value <34 nmol/l had 100% sensitivity for SST failure. Using these cut-offs, 50% (n=83) of SSTs performed on patients prescribed inhaled GCs were unnecessary.

CONCLUSION

Adrenal suppression due to GC treatment, particularly inhaled GCs, is common. A basal serum cortisol concentration has utility in helping determine which patients should undergo dynamic assessment of adrenal function.