Tuesday, March 15, 2011

Some Comments on Radiation from Japan

There is a lot of conflicting information about radiation releases from power plants in Japan. It's a keen health concern for millions of people around the world, including me, and my hope with this post is to add a little clarity where I can. Here are some key points.

Today's maximum reported radiation release of 400 millisevierts is equivalent to 40 rem in the US system of measuring these things. That's about the maximum you could tolerate in a month. A few people would experience nausea, vomiting, and, about a month later, lower white blood cell counts.

Potassium iodide only protects against radioactive iodine, not other radioactive heavy elements like cesium and strontium. And it only protects against thyroid cancer. Protecting against thyroid cancer is a good thing, but you should neither suppose that having KI on hand is all you need or that you necessarily need to rush out and get it.

It's easy to forget that there have been hundreds of much larger releases of radiation into the atmosphere during the era of above-ground testing of nuclear weapons. Humankind survived. I don't mean to minimize any of the risks, but it's not time to panic yet, outside of the nuclear disaster zone in Japan. Comments are welcome.

Saturday, March 5, 2011

Is HbA1C the Best Way to Diagnose Diabetes in Kids?

Glycated hemoglobin, also known as HbA1C, has long been touted as the gold standard for diagnosing diabetes. If your HbA1C is above 5.0%, some experts opine, or 7.0%, in the opinion of others, then you need to start practicing blood control. But HbA1C is a problematic measurement.

HbA1C is a measurement of the percentage of red blood cells that have bonded to glucose. The higher your blood sugar levels, the more red blood cells that sugar-coated. This glycation of the red blood cell continues throughout its life cycle, so HbA1C is thought to be a good measurement of the average blood sugar level over the last 90 to 120 days, the average life span of a red blood cell.

Except when it isn't.

Dr. Joyce Lee of the Mott Children's Hospital at the University of Michigan questions the diagnostic value of HbA1C in detecting diabetes in teens. Young people in their growth spurt are increasing their volume of blood, effectively diluting the percentage of red blood cells that is glycated. If a child has risk factors for diabetes, such as family history and overweight, then some other test is indicated.

Like a finger stick while fasting in the morning and a finger stick 120 minutes after a meal. Sometimes the most useful technology is not the most expensive.

Just taking a fasting blood sugar level, by the way, is not necessarily a good way to test for early type 2 diabetes. The ability of the pancreas to handle "phase 1" secretion, producing insulin right after a meal, is usually the first to go.

High blood sugar readings right after meals are a better indication of incipient diabetes than high blood sugar readings first thing in the morning, because even a sick pancreas sometimes can can catch up overnight. But HbA1C is not the best way to measure this.