Little-used measure of good cholesterol can predict heart attack and stroke risk

For decades, high-density lipoprotein (HDL) cholesterol has been dubbed "good cholesterol" because of its role in moving fats and other cholesterol molecules out of artery walls.

People with higher HDL cholesterol levels tend to have lower rates of cardiovascular disease, studies have shown.

Now, UT Southwestern scientists have analyzed data on more than 15,000 people to better understand the association between HDL cholesterol, heart attacks, and strokes in diverse populations.

They found that the number of HDL particles, a little-used measurement of HDL, is a more reliable predictor of heart attack and stroke risk than the standard HDL cholesterol metric.

Moreover, they found that among black people, neither HDL measurement was significantly associated with heart attack.

According to the Centers for Disease Control and Prevention, heart disease is the leading cause of death in the U.S. More than 12 percent of adults in the U.S. have high total cholesterol levels, and more than 18 percent have what's currently considered low levels of HDL cholesterol.

Cholesterol is a waxy substance that is used by the body to make hormones and keep cells functioning properly. But when low-density lipoprotein (LDL) cholesterol levels are too high, cholesterol can accumulate inside blood vessels, forming deposits called plaques.

These plaques can eventually lead to blood vessel blockages that cause heart attacks or strokes. HDL cholesterol helps remove cholesterol from blood vessels.

But recent studies have come to mixed conclusions about the association between HDL cholesterol levels and health outcomes.

For the new paper, published in the journal Circulation, Rohatgi and his colleagues pooled together information on people who had participated in four large, nationwide studies – the Dallas Heart Study, Atherosclerosis Risk in Communities study, Multi-Ethnic Study of Atherosclerosis, and the Prevention of Renal and Vascular Endstage Disease study.

In the study, people with the highest HDL-P levels, above 37 mmol/L, had a 37 percent lower risk of heart attack and a 34 percent lower risk of stroke than those who had the lowest HDL-P levels.

A better understanding of how HDL can help predict disease, and how that association varies among populations, is vital to lowering rates of cardiovascular disease, the researchers say.

 

 

БИЛЕТ 9

1. High Blood Pressure in Children. By Sally Robertson, B.Sc.

 

Although people usually assume that only middle-aged or elderly people develop high blood pressure (hypertension), it is also possible for the condition to arise in teenagers, children and even babies.

The American Heart Association advises that all children should be checked for high blood pressure on a yearly basis, as detecting the condition and treating it early will improve the child’s health and reduce or prevent the harmful effects of the condition.

Causes

Hypertension in children is usually caused by another underlying health condition such as heart disease or kidney disease. Itis therefore referred to as secondary hypertension and once the medical condition is resolved, the blood pressure typically returns to normal. Secondary hypertension may also be caused by the following conditions:

Hyperthyroidism

Adrenal disorder

Sleep problems, particularly sleep apnea

Renal artery stenosis

Some medications can increase blood pressure, but, again, the blood pressure usually returns to normal if the medication is discontinued.

In some cases, a doctor cannot determine what is causing the hypertension, in which case the condition is referred to as primary or essential hypertension. Various factors that are known to contribute to the risk of primary hypertension include:

Overweight or obesity (body mass index >25)

Family history of hypertension

High cholesterol and triglycerides

Type 2 diabetes or raised fasting blood sugar

Complications

Children with hypertension often develop sleep apnea and breathe abnormally while they sleep, particularly if the child is overweight. If the hypertension persists into adulthood, the person is at an increased risk of kidney disease, stroke, heart attack and heart failure.

Tests and diagnosis

Blood pressure is measured using an inflatable arm cuff and blood pressure gauge. The blood pressure measurement is made up of two readings. The first (upper) number is a measurement of systolic blood pressure, which is the pressure in the arteries when the heart beats. The second (lower) number is a measurement of the diastolic pressure, which is the pressure in the arteries between heartbeats.

One blood pressure measurement is not sufficient to diagnose hypertension. In order to be diagnosed, the child needs to have an abnormal reading on at least three visits to the doctor, and during a visit, the measurement may be taken several times to ensure it is accurate.

 

What is considered as “normal” blood pressure is relative and depends on the child’s gender, age and height. If hypertension is diagnosed, the child should then be checked approximately every six months. A doctor may also perform the following tests to check for other underlying conditions that may be causing the problem:

Echocardiogram to check blood flow through the heart

Ultrasound to assess the kidneys

Blood test to check blood cell counts, blood glucose and function of the kidneys

Urine analysis

Treatment

Hypertension in children is generally managed by making lifestyle changes such as exercising regularly, eating a diet that is good for the heart and maintaining a healthy weight. If these measures alone are not enough to resolve the problem, medications may be prescribed.