Adrenal venous sampling in primary aldosteronism: lessons from over 600 single-operator procedures.

Adrenal vein sampling (AVS) is a recommended if not required final diagnostic step in the investigation of primary aldosteronism, the most common cause of remediable secondary hypertension. Successful adrenal vein sampling is operator-dependent. Having performed over 600 such procedures at our centre over 20 years, our single-operator experience is described in detail for the purpose of training future radiologists as well as for use by those who are planning to start an AVS programme of their own. This updated review considers new developments in primary aldosteronism disease understanding that are relevant for AVS performance and protocols, along with technical enhancements that may be used for special cases. Detailed understanding of variant anatomy and tips for successful cannulation are keys to success, along with an endocrinology and clinical chemistry partnership for continuous quality control. A successful AVS programme offers patients a hope for cure of resistant hypertension.

Very high rate of false positive biochemical results when screening for pheochromocytoma in a large, undifferentiated population with variable indications for testing.

OBJECTIVE: Pheochromocytoma/Paraganglioma (PPGL) is a rare tumor with non-specific presentations overlapping common entities like anxiety, hypertension, acute illness and episodic "spells." Assessment of urine normetanephrine or metanephrine (UNM-UMN) in real-life, where PPGL is very rare and PPGL mimics extremely common, may show overlap in results with loss of specificity depending on the reference range. We determined the extent to which UNM-UMN are high in people undergoing screening for PPGL. DESIGN AND METHODS: Retrospective review of all UNM-UMN performed in a central lab serving Southern Alberta over 8 years. RESULTS: After excluding pediatric ages and patients with CKD, there were 12,572 unique patients with 14,383 measures of UNM-UMN. 85 patients (0.7%) had markedly high UNM-UMN compatible with likely PPGL. Depending on the age category (in decades), 10-22% of all UNM results were above the upper reference limit(URL), particularly between ages of 40-60. Less than 3% had elevations in both UNM and UMN. Of those with high UNM, 99% were less than 3-fold the URL. Based on the population data, a potential new reference range for UNM is suggested, which may be more appropriate to the types of patient who undergo this form of testing. CONCLUSIONS: There is an extraordinarily high prevalence of high UNM seen in real-life use of the test. However, the vast majority of high UNM are unlikely to be PPGL given the disease rarity and the massive number of tests ordered. This suggests the current laboratory URL may be too low (poor specificity) and/or the reference range may not be appropriate to the type of patient being screened for PPGL. Depending on the frequency of use of any screening test in a population, if the disease is rare and the specificity of the test is poor, a high rate of false positive results will be expected.

Cyclosporin neurotoxicity in cardiac transplant recipients.

Cyclosporin toxicity may produce a wide range of neurological disorders. We report three patients whose neurological problems developed while taking cyclosporin following cardiac transplantation, but resolved rapidly when the drug was discontinued. In two cases, MRI revealed abnormalities which disappeared with clinical recovery. Blood cyclosporin concentrations were not markedly increased, and it is possible that the neurotoxic effects of cyclosporin are mediated by metabolites, through an effect on the blood-brain barrier.