Blood pressure measures the force exerted by blood against artery walls. It has two numbers: systolic and diastolic. Systolic, the top number, is pressure when your heart contracts. Diastolic, the bottom number, is pressure when your heart relaxes and fills with blood. Understanding both numbers provides a comprehensive view of your cardiovascular health.
Understanding Low Diastolic Pressure
Low diastolic pressure, or isolated diastolic hypotension, occurs when the lower blood pressure number falls below a typical threshold while the systolic number remains normal. A diastolic reading below 60 mmHg is generally considered low. While overall low blood pressure (hypotension) is below 90/60 mmHg, only the diastolic number can be low. This is important because the heart’s coronary arteries receive oxygen-rich blood during the relaxation phase. If diastolic pressure is too low, the heart may not receive adequate blood and oxygen, potentially weakening it over time.
Common Reasons for Low Diastolic Readings
Several factors can contribute to low diastolic pressure. Physiological factors include dehydration, which reduces blood volume, and standing up too quickly, known as orthostatic hypotension, which causes a temporary dip. Pregnancy also commonly causes a drop due to hormonal changes.
Medications are a frequent cause, including certain blood pressure drugs, diuretics, erectile dysfunction medications, and some antidepressants. Underlying medical conditions like heart failure, heart valve issues, a slow heart rate, endocrine disorders (e.g., adrenal insufficiency, thyroid conditions), or severe infections (e.g., sepsis) can also play a role. Lifestyle factors, such as prolonged bed rest or nutritional deficiencies, can influence blood pressure. For some individuals, particularly very fit athletes, naturally lower readings can be normal and not indicate a health problem.
Signs and Symptoms of Low Diastolic Pressure
When diastolic pressure is too low, the body may not receive sufficient blood flow, leading to various symptoms. Common signs include dizziness or lightheadedness due to reduced blood supply to the brain, and fainting when blood pressure drops significantly. Other symptoms include blurred vision, nausea, fatigue, weakness, and a lack of concentration. In severe cases, cold, clammy, pale skin and rapid, shallow breathing can indicate organs are not receiving enough oxygen. Some studies also suggest an association between low diastolic pressure and depression.
When Low Diastolic Pressure Requires Attention
Not every low diastolic reading requires medical intervention, especially if no symptoms are present. However, consult a doctor if symptoms appear or worsen, or if the low diastolic pressure is a new development rather than a long-standing personal norm. Concerns about medication side effects that might be contributing to low readings also warrant discussion with a healthcare provider. If low diastolic pressure occurs after an injury or illness, professional evaluation can help determine the underlying cause. A doctor can diagnose the reason and recommend appropriate management, including lifestyle adjustments or treating any identified underlying conditions.