Blood pressure is a measurement representing the force of blood moving through the body’s arteries. A reading like 117/57 millimeters of mercury (mmHg) features a systolic number that appears optimal and a diastolic number that seems quite low. Understanding the meaning of each number is the first step in assessing this reading.
Decoding the Numbers
A blood pressure reading is always given as two values: the systolic pressure over the diastolic pressure. The top number, the systolic pressure, represents the maximum force exerted against the artery walls when the heart contracts and pushes blood out. The bottom number, the diastolic pressure, measures the force in the arteries when the heart is relaxed and filling with blood between beats. This resting pressure indicates the lowest pressure consistently maintained in the circulatory system.
Interpretation of 117/57
The systolic reading of 117 mmHg falls within the “Normal” blood pressure category for adults, defined as less than 120 mmHg. This value is considered healthy, sitting just below the threshold for “Elevated” blood pressure, which begins at 120 mmHg.
The diastolic number of 57 mmHg is below the upper limit for a normal reading (under 80 mmHg). However, the clinical goal for optimal blood pressure is less than 120/80 mmHg, meaning a diastolic pressure below 60 mmHg is often considered low. When the systolic number is normal but the diastolic number is low, as with 117/57, it is sometimes called isolated diastolic hypotension.
This specific reading is generally considered healthy because the systolic pressure is excellent. However, the low diastolic value introduces a point for discussion, especially if it causes any symptoms. The overall picture suggests a well-managed systolic pressure combined with a diastolic pressure that is on the lower end of the spectrum.
Understanding Low Diastolic Pressure
The diastolic pressure of 57 mmHg is below the 60 mmHg mark that some studies link to potential cardiovascular issues. This number is significant because the coronary arteries, which supply the heart muscle, receive their blood flow during this resting phase. If the diastolic pressure is too low, the heart muscle may not receive adequate blood and oxygen.
This reading results in a pulse pressure of 60 mmHg, calculated by subtracting the diastolic number from the systolic number (117 – 57 = 60). Pulse pressure measures the force the heart generates with each beat and indicates arterial stiffness. A normal pulse pressure is typically around 40 mmHg, and 60 mmHg is at the upper limit of the generally accepted normal range (40–60 mmHg). A low diastolic reading in isolation can be caused by various factors, including high fitness levels, certain medications, or age-related changes in blood vessel elasticity.
Next Steps and Contextual Factors
A single blood pressure reading is only a snapshot in time, and several contextual factors can influence the result. Recent activities like exercise, stress, or consuming caffeine or tobacco can temporarily increase the reading. Improper measurement technique, such as using the wrong cuff size or having an unsupported arm, can also lead to inaccurate results.
For a more accurate assessment, take multiple readings over several days under relaxed conditions. This establishes a reliable personal baseline. If the diastolic reading of 57 mmHg is consistently maintained without any symptoms, it may simply be a normal value for that individual.
If a person experiences symptoms such as lightheadedness, dizziness, fatigue, or fainting, this low diastolic pressure could be a factor. In such cases, or if the pulse pressure remains consistently high, consulting a healthcare provider is the appropriate next step. A doctor can interpret the reading within the full context of a person’s age, medical history, and overall health.