Utility of Cannulated Prolactin to Exclude Stress Hyperprolactinemia in Patients with Persistent Mild Hyperprolactinemia.

BACKGROUND: Stress-induced hyperprolactinemia can be difficult to differentiate from true hyperprolactinema and may result in patients having unnecessary investigations and imaging. We report the results of cannulated prolactin tests with serial prolactin measurements from an indwelling catheter to differentiate true from stress-induced hyperprolactinemia in patients with persistently mildly elevated prolactin levels in both referral and repeat samples. METHODS: Data were collected for 42 patients who had a cannulated prolactin test between January 2017 and May 2018. After cannula insertion, prolactin was measured at 0, 60, and 120 minutes. Normalization is defined as a decline in prolactin to gender-defined normal ranges. RESULTS: The mean age was 33.8 years (SD ± 9.9), and 37 (88%) were female. Menstrual irregularities were the main presenting symptom in 28.57% of the patients. Prolactin normalized in 12 (28.6%) patients of whom cannulated prolactin test was done. Repeat random prolactin levels were significantly higher in patients whose prolactin did not normalize during the cannulated prolactin test. MRI of the pituitary gland showed an abnormality in 23 out of 28 (82%) patients who did not normalize prolactin, a microadenoma in the majority of patients (18 patients). CONCLUSION: The cannulated prolactin test was useful in excluding true hyperprolactinemia in 28.6% of patients with previously confirmed mildly elevated random prolactin on two occasions, thus avoiding over-diagnosis and unnecessary imaging.

The Vanishing Adrenal Glands: A Transient Regression of Adrenal Lymphoma After a Single Dose of 1 mg Dexamethasone.

OBJECTIVE: Dexamethasone is a known treatment for lymphoma, but the potency and rapidity of its effect have not been recognized. We present a case of bilateral adrenal lymphoma that significantly reduced in size after a single dose of dexamethasone. METHODS: We present the clinical course and investigations, including adrenocorticotropic hormone, cortisol, short synacthen test, computed tomography (CT), and adrenal biopsy results. RESULTS: A 52-year-old man had a fall and was incidentally found to have bilateral adrenal masses (left, 6 cm; right, 5 cm) on CT. His adrenal function tests included plasma metanephrines (normetanephrine, 830 pmol/L [normal, <1180]; metanephrine, <100 pmol/L [<510]; 3-methoxytyramine, <100 pmol/L [<180]); aldosterone, 270 pmol/L( 90-700); and random cortisol, 230 nmol/L (160-550). An overnight dexamethasone suppression test with 1 mg of dexamethasone showed cortisol of <28 nmol/L (0-50). A repeat CT scan 8 days thereafter showed adrenal masses of 4.5 and 3.5 cm on the left and right, respectively. He had a follow-up CT scan 3 months later that showed adrenal lesions measuring 8 cm (left) and 9 cm (right). He subsequently presented with fatigue and dizziness. Morning cortisol of 201 nmol/L (160-550) with adrenocorticotropic hormone of 216 ng/L (10-30) indicated primary adrenal insufficiency. Mineralocorticoid and glucocorticoid replacement therapy commenced. An adrenal biopsy showed abnormal enlarged B cells, consistent with a diagnosis of diffuse large B-cell lymphoma. CONCLUSION: A diagnosis of lymphoma should be considered when adrenal lesions shrink following even a single low dose of dexamethasone administered as a part of a diagnostic test.

Synacthen Stimulation Test Following Unilateral Adrenalectomy Needs to Be Interpreted With Caution.

Background: Cortisol levels in response to stress are highly variable. Baseline and stimulated cortisol levels are commonly used to determine adrenal function following unilateral adrenalectomy. We report the results of synacthen stimulation testing following unilateral adrenalectomy in a tertiary referral center. Methods: Data were collected retrospectively for 36 patients who underwent synacthen stimulation testing one day post unilateral adrenalectomy. None of the patients had clinical signs of hypercortisolism preoperatively. No patient received pre- or intraoperative steroids. Patients with overt Cushing's syndrome were excluded. Results: The median age was 58 (31-79) years. Preoperatively, 16 (44%) patients had a diagnosis of pheochromocytoma, 12 (33%) patients had primary aldosteronism and 8 (22%) patients had non-functioning adenomas with indeterminate/atypical imaging characteristics necessitating surgery. Preoperative overnight dexamethasone suppression test results revealed that 6 of 29 patients failed to suppress cortisol to <50 nmol/L. Twenty (56%) patients achieved a stimulated cortisol ≥450 nmol/L at 30 minutes and 28 (78%) at 60 minutes. None of the patients developed clinical adrenal insufficiency necessitating steroid replacement. Conclusions: Synacthen stimulation testing following unilateral adrenalectomy using standard stimulated cortisol cut-off values would wrongly label many patients adrenally insufficient and may lead to inappropriate prescriptions of steroids to patients who do not need them.

A rare cause of severe Cushing's syndrome.

SUMMARY: Ectopic adrenocorticotropic hormone (ACTH) production is an uncommon cause of Cushing's syndrome and, rarely, the source can be a phaeochromocytoma. A 55-year-old man presented following an episode of presumed gastroenteritis with vomiting and general malaise. Further episodes of diarrhoea, joint pains and palpitations followed. On examination, he was hypertensive with no clinical features to suggest hypercortisolaemia. He was subsequently found to have raised plasma normetanephrines of 3.98 nmol/L (NR <0.71) and metanephrines of 0.69 nmol/L (NR <0.36). An adrenal CT showed a 3.8 cm right adrenal nodule, which was not MIBG-avid but was clinically and biochemically consistent with a phaeochromocytoma. He was started on alpha blockade and referred for right adrenalectomy. Four weeks later, on the day of admission for adrenalectomy, profound hypokalaemia was noted (serum potassium 2.0 mmol/L) with non-specific ST-segment ECG changes. He was also diagnosed with new-onset diabetes mellitus (capillary blood glucose of 28 mmol/L). He reported to have gained weight and his skin had become darker over the course of the last 4 weeks. Given these findings, he underwent overnight dexamethasone suppression testing, which showed a non-suppressed serum cortisol of 1099 nmol/L. Baseline serum ACTH was 273 ng/L. A preliminary diagnosis of ectopic ACTH secretion from the known right-sided phaeochromocytoma was made and he was started on metyrapone and insulin. Surgery was postponed for 4 weeks. Following uncomplicated laparoscopic adrenalectomy, the patient recovered with full resolution of symptoms. LEARNING POINTS: Phaeochromocytomas are a rare source of ectopic ACTH secretion. A high clinical index of suspicion is therefore required to make the diagnosis. Ectopic ACTH secretion from a phaeochromocytoma can rapidly progress to severe Cushing's syndrome, thus complicating tumour removal. Removal of the primary tumour often leads to full recovery. The limited literature suggests that the presence of ectopic Cushing's syndrome does not appear to have any long-term prognostic implications.