An adrenal mass and increased catecholamines: monoamine oxidase or pheochromocytoma effect?

Hormonal evaluation in patients with an adrenal incidentaloma can be difficult in patients with comorbidities or in patients using interfering drugs. We present a case of a 54-year-old man who was evaluated for an adrenal mass. The medical history reported treatment with a monoamine oxidase (MAO) inhibitor for recurrent psychoses. Hormonal screening showed elevated levels of normetanephrine and metanephrine in plasma and urine, suggesting a diagnosis of pheochromocytoma (PHEO), and an adrenalectomy was performed. Histologic examination showed that the tumor had an origin of the adrenal cortex. MAO inhibitors are also known to cause elevated levels of catecholamines. In this case, a PHEO seemed more likely the cause due to repeatedly elevated levels of metanephrines and normal levels of catecholamines. Since the tumor had an origin of the adrenal cortex, the use of MAO inhibitors was the most likely explanation for the elevated levels of metanephrines. This case illustrated the difficulties in diagnosing PHEO, especially in patients with comorbidities and interfering drug

Evaluating clinical accuracy of continuous glucose monitoring devices: other methods

With more and more continuous glucose monitoring devices entering the market, the importance of adequate accuracy assessment grows. This review discusses pros and cons of Regression Analysis and Correlation Coefficient, Relative Difference measures, Bland Altman plot, ISO criteria, combined curve fitting, and epidemiological analyses, the latter including sensitivity, specificity and positive predictive value for hypoglycaemia. Finally, recommendations for much needed head-to-head studies are given. This paper is a revised and adapted version of How to assess and compare the accuracy of continuous glucose monitors?, Diabetes Technology and Therapeutics 2007, in press, published with permission of the edito

Comparison of a needle-type and a microdialysis continuous glucose monitor in type 1 diabetic patients

OBJECTIVE - We examined the reliability of two continuous glucose sensors in type 1 diabetic patients at night and during rapid glucose excursions and verified the hypothesized nocturnal hypoglycemic drift of the needle-type sensor (CGMSgold) and delay of the microchalysis sensor (GlucoDay). RESEARCH DESIGN AND METHODS - Blood was sampled overnight twice per hour in 13 patients. Rapid-acting insulin was given subcutaneously 30 min after breakfast. Sampling once per minute started 45 min after breakfast and 75 min After insulin injection for 30 min, with the aim of determining peak and nadir glucose values. Mean absolute differences (MADs) between sensor and blood glucose values were calculated. Sensor curves were modeled for all patients using linear regression. Horizontal and vertical shifts of sensor curves from the blood glucose curves were assessed. A vertical shift indicates sensor drift and a horizontal shift sensor delay. RESULTS- Drift was minimal in the needle-type and microdialysis sensors (-0.02 and - 0.04 mmol/l). Mean +/- SD delay was 7.1 +/- 5.5 min for the microdialysis sensor (P <0. 001). MAD was 15.0% for the needle-type sensor and 13.6% for the microdialysis sensor (P = 0.013), After correction for the 7-min delay, the microdialysis MAD improved to 11.7% (P <0.0001). CONCLUSIONS - The microdialysis sensor was more accurate than the needle-type sensor, with or without correction for a 7-min delay. In contrast to the previous version, the current needle-type sensor did not exhibit nocturnal hypoglycemic drift. Continuous subcutaneous glucose sensors are valuable adjunctive tools for glucose trend analyses. However, considering the large MADs, individual sensor values should be interpreted with cautio

Relationship between interstitial and blood glucose in type 1 diabetes patients: delay and the push-pull phenomenon revisited

BACKGROUND: Interpretation of glucose sensor results requires clarification of the relationship between interstitial (IG) and blood (BG) glucose. We examined the delay of IG upon BG change and reinvestigated the push-pull phenomenon in type 1 diabetes patients. The push-pull phenomenon postulates that IG shows a delayed increase but earlier decrease compared to BG. If so, postprandial sensor curves should have narrower peak widths than BG curves. METHODS: For both sensors a two-point calibration procedure was used. Delay was assessed by shifting combined fitted postprandial glucose sensor curves horizontally. The sensor and BG peak widths of the separately fitted curves were assessed and compared. Peak width was re-assessed for the microdialysis sensor using raw current values to rule out any calibration effect on the shape of the curve. The contribution of instrumental delay to the earlier reported 7.1-min delay of the microdialysis sensor was calculated. RESULTS: No delay [-2.2 +/- 6.2 (SD) min] was seen for the needle-type sensor. Instrumental delay was >6.2 min for the microdialysis sensor, accounting for more than 87% of the total reported delay of 7.1 +/- 5.5 min. Mean peak width for the BG curves was 100.8 +/- 25.0 min, for the needle-type sensor curves 110.0 +/- 20.5 min, and for the microdialysis sensor curves 104.6 +/- 21.7 min (P = 0.052 and P = 0.11 vs. BG, respectively). Mean peak width for the uncalibrated microdialysis current values was 105.0 +/- 23.1 min, which was not different from the peak width of the BG curves (P = 0.347). CONCLUSIONS: IG-BG delay may be smaller than previously postulated. The sensor curves tended to have broader peaks than the BG curves, in contrast to the expected narrower peaks predicted by the push-pull phenomenon. This argues against the existence of the push-pull phenomeno

Nocturnal hypoglycaemia in type 1 diabetes - consequences and assessment

Hypoglycaemia is inevitable when striving for low HbA(1c) values. Nocturnal hypoglycaemia often occurs without symptoms, but results in diminished next day well-being and hypoglycaemia unawareness. Frequency of nocturnal hypoglycaemia was first assessed in research ward settings, but suffered from insufficient glucose sampling frequency. This may have resulted in overestimation of the duration of hypoglycaemic episodes. The advent of the first continuous glucose sensor, the needle-type MedtronicMiniMed Continuous Glucose Measurement System, revolutionized the assessment of glucose values. However, on scrutiny, the first version of this sensor showed a drift into the hypoglycaemic area and delayed recovery from hypoglycaemia. Using the microdialysis-based GlucoDay system, our group reported a lower frequency of nocturnal hypoglycaemia in type 1 diabetes patients using an insulin pump, than that expected from the existing literature. Today, more than 80 years after the introduction of insulin for the treatment of type 1 diabetes, the associated frequency of nocturnal hypoglycaemia still awaits its definitive assessment. Copyright (C) 2004 John Wiley Sons, Lt