Diagnosis of hyperinsulinaemia in a normoglycaemic healthy Indian Population--developing ethnic reference ranges.

CONTEXT: Reference limits for diagnosing hyperinsulinaemia are currently derived from non-Indian cohorts and have not been validated in Indians even though it is acknowledged that different patterns of insulin secretion are seen across ethnicities. AIMS: To develop ethnicity specific reference limits for insulin levels in a normoglycaemic healthy Indian cohort in order to derive a clinical cut off for hyperinsulinaemia as an effective screening tool for predicting future risk of metabolic and cardiovascular disease. SETTINGS AND DESIGN: Prospective analysis of plasma insulin levels in healthy normoglycaemic volunteers availing diagnostic facilities at a central reference laboratory in Mumbai. METHODS AND MATERIAL: 122 normoglycaemic males between 19-73 years and 126 females between 19-55 years of age were selected based on a screening questionnaire as per the Clinical Laboratory and Standards Institute (CLSI) guidance document for deriving reference ranges. Fasting insulin levels were analysed using a Chemiluminescent Microparticle Immunoassay platform and derived results were analysed to determine reference limits for insulin. STATISTICAL ANALYSIS USED: A non-parametric method of statistical analysis was used to determine the 2.5 and 97.5% limits with 90% confidence intervals. RESULTS: Reference range for insulin in a normoglycemic Indian cohort was derived as 2.7-17 uIU/ml which established 17 uIU/ml as the clinical cut off for diagnosing hyperinsulinemia in healthy Indians. CONCLUSIONS: Reference limits for insulin in normoglycemic Indians needs to be revised to 2.7-17 uIU/ ml. Clinical cut off for hyperinsulinemia needs to be lowered to 17 uIU/ml from currently used cut offs which range from 25-31 ulU/ml. KEY MESSAGES: Reference limits currently used for diagnosing hyperinsulinemia in healthy normoglycemic adults need to be revised and made specific for different ethnicities. In Indians the upper limit of the normal reference range for insulin levels needs to be brought down to 17 uIU/ml from the existing 25-31 u IU/ml. This modified cut off would help clinicians identify apparently healthy individuals who may need to be screened for a future risk of metabolic and cardiovascular disorders.

Oxidative stress and low dose ionizing radiation.

The field of radiation biochemistry has provided tremendous impact in recent years as extensive research on free radicals has implicated them in radiation damage. An important offshoot of this field is the branch dealing with radiological protection in medical applications like diagnostic radiology. Hence, we decided to investigate the relationship between oxidative stress and low dose ionizing radiation (x-rays) in the work environment of x-ray technicians (radiographers), by comparing their RBC malondialdehyde, % hemolysis, catalase and plasma vitamin E levels with those of controls. There was a significant increase in the susceptibility of RBCs to hemolysis in radiographers compared to controls. Malondialdehyde and catalase levels were slightly increased in the radiographers, but this did not disturb the steady state concentration of their plasma vitamin E. These findings go in favour of theories stating that exposure to low dose ionizing radiation does cause a greater amount of oxidative stress, than that caused during normal routine metabolic processes.