Ask the Doctors: July 2017
I have elevated cholesterol, and for many years when I had blood work I was told to fast for 12 hours. Recently my primary care physician said that a non-fasting measurement would be as accurate. I have diabetes, and episodes of low blood sugar and fasting can sometimes cause a symptomatic drop in my blood sugar. What do you think?
The standard for measuring cholesterol for many decades has been with a fasting blood sample, and treatment guidelines had recommended this. The rationale was to reduce variability between measurements and to allow for more accurate estimation of the LDL cholesterol (LDL-C). This is primarily due to the effects of a meal on variability in triglyceride levels. In reality the increase in triglycerides in most individuals after food intake is less than previously thought. Studies have shown that on average the differences with non-fasting samples in HDL-C, total cholesterol and non-HDL-C are negligible, with less than a 10 percent lower calculation of LDL-C. These differences do not have a major impact on assessment of future cardiovascular risk or treatment decisions. In 2016 many guidelines originating from Europe and Canada have specified that fasting lipid profiles are not routinely required and non-fasting samples may be used in the majority of patients. The U.S. guidelines still prefer a fasting sample, although even these indicate that it’s not mandatory. Non-fasting samples may be beneficial in people such as yourself prone to low blood sugars when fasting, the very elderly, or those in whom taking morning medications with foods is necessary. The main caution is in individuals with significantly elevated triglycerides or those being treated with medications that may alter triglycerides. Comparing a fasting to a non-fasting sample for assessing response to therapy may be somewhat misleading in these cases. In addition, most of the standards for defining normal lipid levels are based on fasting samples. As long as your physician understands these differences and applies them to treatment decision-making, a non-fasting lipid panel is suitable for many individuals.
I’ve read online that there is little evidence to support the use of statins in the primary prevention of cardiovascular disease and that the risks outweigh the benefits. I have no previous cardiovascular disease. How do I know if I should take statins?
Cardiovascular disease (CVD) has become the leading cause of death worldwide, responsible for over 30 percent of yearly deaths. Often, a heart attack or stroke is the first clinical sign of CVD, leading to death or significant morbidity. Diabetics, for example, are at high risk of developing CVD even if they have no previous history. A strong relationship exists between CVD and multiple risk factors, including high cholesterol. Therefore, identifying those at risk before the disease is clinically evident and treating the risk factors responsible makes sense. Many tools are available using factors such as age, gender, cholesterol, smoking status and blood pressure to estimate 10-year and lifetime risk of developing CVD. In those at high risk, aggressive treatment of risk factors, including cholesterol, should be considered. Statins remain the main therapy to correct cholesterol abnormalities, but more importantly have been proven to reduce future adverse CVD events both in secondary and primary prevention populations. In addition, analysis of primary prevention trials has demonstrated a 31 percent reduction in CVD death with statins. The higher the estimated risk, the greater the absolute benefit. If your estimated likelihood of having a heart attack or stroke over 10 years exceeds 7.5-10 percent, statin therapy should be considered and discussed with your physician. Risk assessment tools are somewhat crude estimates. Characteristics of the patient and risks of long-term exposure to a medication need to be taken into account when making a final treatment decision.