Reader Reaction and Timely Answers From Experts (May 2005)

Fungus Identification 101 What is the best way to obtain skin scrapings and evaluate them for evidenceof fungal infection? — MD There are several methods by which material for potassium hydroxide examination for fungal elements can be collected. A very effective method is to stroke the affected skin gently with a glass slide to produce scale, which is collected on another glass slide. With some hyperkeratotic lesions, preparatory debriding of excess keratin is recommended to make the examination more efficient. The edge of a scalpel can also be used; however, use of a scalpel increases the risk of accidentally cutting the patient. Some sites can be debrided with an alcohol wipe, especially when maceration or weeping is present, but remember that alcohol stings. Once you have obtained the specimen, apply a thin layer of potassium hydroxide to the scrapings on the slide, then gently heat the undersurface of the slide with a match to melt the keratin and thus facilitate the identification of fungal elements. Do not heat the slide to the point at which the potassium hydroxide bubbles; if this happens, the chemical will crystallize and make identification more difficult. It is not uncommon for even experienced clinicians to require more than one attempt to identify fungal elements. To build competence at identifying fungi, practice on patients in whom tinea versicolor is suspected (Figure). In this condition, fungal elements are abundant and can be identified quickly and relatively easily.   — David L. Kaplan, MD Clinical Assistant Professor of Dermatology University of Missouri Kansas City School of Medicine     How to Manage Insulin Resistance in Children on next page , How to Manage Insulin Resistance in Children I very much appreciated the discussion of diabetes screening in children by Drs Michael Haller and Desmond Schatz (CONSULTANT, November 2004, page 1609). As recommended by the authors, I commonly order a fasting lipid profile and measurements of glucose and insulin levels in children at risk for type 2 diabetes. One area of management that remains confusing is the approach to take with children who have an elevated fasting insulin level but otherwise normal laboratory results (including HbA1c  level). What further workup, management, referral, and (if needed) treatment do the authors recommend for these patients? — Jeffrey Zaref, MD, MPH Framingham, Mass You pose a very interesting question: What management approach is appropriate in obese children whose screening results reveal evidence of insulin resistance but not overt diabetes? As the obesity epidemic continues, increasing numbers of children are exhibiting evidence of insulin resistance. Although type 2 diabetes will develop in some of these children, the majority will persist in a state of insulin resistance for many years. Insulin resistance is a major component of the metabolic syndrome. In adults, this syndrome has been defined as the presence of at least 3 of the following: •Abdominal obesity. •Hypertriglyceridemia. •Low high-density lipoprotein cholesterol level. •Hypertension. •Insulin resistance. The metabolic syndrome lacks a standardized pediatric definition. However, several studies have shown that increased risk of cardiovascular disease (CVD) is associated with obesity and insulin resistance in childhood.1,2 Thus, we believe that children should be screened for the various components of the metabolic syndrome and treated when screening reveals abnormalities. Treatment of insulin resistance. The major component of the metabolic syndrome, insulin resistance, is best treated with lifestyle changes such as increased exercise and reduced caloric intake. Although convincing patients to change their exercise and eating habits is often a daunting task, a mere 5% decrease in weight can effectively prevent the onset of type 2 diabetes. Frequent follow-up, combined with constant reiteration of the importance of weight loss and exercise, is required to change behavior. However, if diet and exercise regimens fail and the patient has a comorbidity such as impaired glucose tolerance or polycystic ovary disease, consider metformin therapy. Treatment of hyperlipidemia and hypertension. Treat these conditions aggressively as well. Monitor blood pressure and determine blood pressure percentile through the use of age-, sex-, and height-adjusted tables. In children, hypertension is defined as blood pressure greater than the 95th percentile on more than 3 occasions. If lifestyle changes fail to normalize blood pressure, initiate antihypertensive therapy. Treat hyperlipidemia in a similarly aggressive manner in high-risk children. In our practice, we treat any child with a family history of diabetes and a lowdensity lipoprotein cholesterol level greater than 130 mg/dL or a triglyceride level greater than 150 mg/dL. In children older than 10 years, we prescribe statin therapy. Diabetes screening.  Screen for diabetes every 1 to 2 years in any child older than 10 years who is obese and has other risk factors for type 2 diabetes.3  Although the American Diabetes Association recommendations are to screen by using fasting blood glucose levels, we believe that these blood levels have poor sensitivity in high-risk patients. An oral glucose tolerance test is highly sensitive but is time-consuming and expensive. Thus, we prefer to use a 2-hour postprandial blood glucose level; this is easily obtained and highly sensitive. In patients of all ages, insulin resistance and prediabetes are substantial risk factors for CVD and death. Thus, aggressive early treatment of comorbidities is indicated to decrease future cardiovascular risk in obese children with insulin resistance. — Michael J. Haller, MD Pediatric Endocrinology Fellow — Desmond A. Schatz, MD Professor of Pediatrics Department of Pediatrics University of Florida Gainesville REFERENCES: 1. Berenson GS. Childhood risk factors predict adult risk associated with subclinical cardiovascular disease. The Bogalusa Heart Study. Am J Cardiol. 2002;90:3L-7L. 2. Li S, Chen W, Srinivasan SR, et al. Childhood cardiovascular risk factors and carotid vascular changes in adulthood: the Bogalusa Heart Study. JAMA. 2003;290:2271-2276. 3. American Diabetes Association. Type 2 diabetes in children and adolescents. Diabetes Care. 2000;23:381-389   Exercise: Fit for All Ages on next page , Exercise: Fit for All Ages My healthy 74-year-old patient exercises 30 minutes 3 times a week and 60 minutes twice a week at a rate of 3.5 to 3.8 miles per hour. He perspires considerably after 20 minutes without any other adverse effects and has done this for more than 30 years. Is it time for him to change or slow down—or should he continue the same exercise regimen? — Rudi Kirschner, MD Phoenix When comparing oxygen transport as measured by maximum oxygen consumption (VO2 max), a fit 74-year-old is biologically similar to a man 30 years younger. Thus, the calendar is a meaningless biomarker. I would praise and encourage your patient. It is never too early or too late in life to exercise.  — Walter M. Bortz II, MD Clinical Associate Professor of Medicine Stanford University School of Medicine Palo Alto, Calif