Biomedical subjects
Publications and source records attributed to John Newell-Price.
Cushing's syndrome results from lengthy and inappropriate exposure to excessive glucocorticoids. Untreated, it has significant morbidity and mortality. The syndrome remains a challenge to diagnose and manage. Here, we review the current understanding of pathogenesis, clinical features, diagnostic, and differential diagnostic approaches. We provide diagnostic algorithms and recommendations for management.
CONTEXT: There are few large series of patients with ectopic, nonpituitary, corticotropin (ACTH) secretion (EAS). OBJECTIVE: The objective of this study was to analyze the clinical, biochemical, and radiological features, management, and treatment outcome of patients with EAS. DESIGN: This was a retrospective case-record study. SETTING: The setting for this study was a tertiary referral hospital center. PATIENTS: Forty patients with EAS were studied. MAIN OUTCOME MEASURES: Clinical, biochemical, and radiological features and response to therapy and survival were measured. RESULTS: The median follow-up was 5 yr (range, 2-30 yr). None of the dynamic tests achieved 100% accuracy, but bilateral inferior petrosal sinus sampling showed an absent central gradient in all but one case (one of 12). Imaging correctly identified the lesion at first investigation in 65% of cases. Bronchial carcinoid tumors were the most common cause of EAS (n = 12; 30%), followed by other neuroendocrine tumors (n = 13, 32.5%). In 12.5% of patients, the source of EAS was never found. Octreotide scintigraphy and whole-body venous sampling were of limited value. Surgical attempt at curative resection was successful in 83% (10 of 12) of patients with bronchial carcinoid tumors; others responded generally well to adrenolytic therapy or bilateral adrenalectomy. Tumor histology and the presence of distant metastases were the main predictors of overall survival (P < 0.05). CONCLUSIONS: A variety of tests and imaging studies are necessary for the correct diagnosis of the EAS, but even then, up to 20% of cases present a covert or occult EAS syndrome. These cases require a prolonged follow-up, review, and repetition of diagnostic tests and scans.
BACKGROUND: The excess mortality and morbidity associated with acromegaly are secondary to prolonged elevation of GH and IGF-I. Vigorous control of these biochemical parameters results in improved morbidity and mortality. Somatostatin analogues (SAs) allow adequate control of GH and IGF-I in approximately 65% of subjects, leaving a significant cohort uncontrolled. Dopamine agonists (DAs), a cheap alternative to SAs, allow control of GH and IGF-I in less than 20% of patients with acromegaly. AIMS: To assess the effectiveness of adding DA therapy to SA in the biochemical control of acromegaly. SUBJECTS: One hundred and twenty cases from the Sheffield Acromegaly Register were reviewed; 24 (20%) did not require medical treatment following pituitary surgery alone; 16 (13%) had safe GH levels following surgery and radiotherapy; and 58 (48%) required medical treatment despite having had surgery, radiotherapy or both. The remaining 22 (18%) received only medical treatment. METHODS: In nine subjects a DA (three bromocriptine, six cabergoline) was added to an SA to control active disease. GH day curves and IGF-I levels were compared before and after the addition of a DA to existing SA treatment. All were on stable maximum-dose treatment with an SA, with inadequate biochemical control prior to addition of DA therapy. Mean duration of treatment on a DA before biochemical assessments were made was 10.3 months. Six subjects had previously been treated with either transsphenoidal surgery, radiotherapy or both. In three subjects SA was the primary therapy. RESULTS: All subjects exhibited a fall in median GH and IGF-I levels. Introduction of a DA resulted in a 36.1% reduction in median GH levels (8.3 vs 5.3 mIU/l; P = 0.008) on a GH day curve and a 35.2% reduction in IGF-I levels (387.2 vs 251.0 microg/l; P = 0.018). Only four subjects had elevated prolactin levels prior to the addition of a DA (>368 mIU/l). CONCLUSION: Addition of DAs to SAs is of benefit in the biochemical control of acromegaly and should be considered in those inadequately controlled. Furthermore, the beneficial effects of DAs occur even when pre-treatment prolactin levels are within the normal range.
OBJECTIVE: The objective of this study was to examine the variables determining hydrocortisone (HC) disposition in patients with adrenal insufficiency and to develop practical protocols for individualized prescribing and monitoring of HC treatment. DESIGN AND PATIENTS: Serum cortisol profiles were measured in 20 cortisol-insufficient patients (09.00 h cortisol < 50 nmol/l) given oral HC as either a fixed or 'body surface area-adjusted' dose in the fasted or fed state. Endogenous cortisol levels were measured in healthy subjects. Pharmacokinetic analysis was performed using P-Pharm software, and computer simulations were used to assess the likely population distribution of the data. RESULTS: Body weight was the most important predictor of HC clearance. A fixed 10-mg HC dose overexposed patients to cortisol by 6.3%, whereas weight-adjusted dosing decreased interpatient variability in maximum cortisol concentration from 31 to 7%, decreased area under the curve (AUC) from 50 to 22% (P < 0.05), and reduced overexposure to < 5%. Food taken before HC delayed its absorption. Serum cortisol measured 4 h after HC predicted cortisol AUC (r(2) = 0.78; P < 0.001). CONCLUSIONS: We recommend weight-adjusted HC dosing, thrice daily before food, monitored with a single serum cortisol measurement using a nomogram. This regimen was prospectively examined in 40 cortisol-insufficient patients, 85% of whom opted to remain on the new thrice-daily treatment regimen.
Explore the source record for details and available documents.
Explore the source record for details and available documents.