First, it should be noted that eNotes answers are intended for study purposes only and are not intended as medical advice. If you have questions about symptoms or other health issues, you should contact a professional health care provider.
First, there is significant variation in blood pressure, depending on age, genetics, fitness level, cardiovascular health, and various other factors. In general, low blood pressure or hypotension is not considered a condition in itself but a possible symptom of a variety of underlying causes. Low blood pressure can be caused by dehydration or bleeding, both of which can reduce blood volume. Certain medications can also cause low blood pressure as can various medical conditions.
Hypotension is the medical term for low blood pressure (less than 90/60 mm/Hg).
A blood pressure reading appears as two numbers. The first and higher of the two is a measure of systolic pressure, or the pressure in the arteries when the heart beats and fills them with blood. The second number measures diastolic pressure, or the pressure in the arteries when the heart rests between beats.
Normal blood pressure is usually in the range of 120/80 mmHg (systolic/diastolic). In healthy people, especially athletes, low blood pressure is a sign of good cardiovascular (heart and blood vessel) health. But low blood pressure can be a sign of an underlying problem - especially in elderly people - where it may cause inadequate blood flow to the heart, brain and other vital organs.
The cause of low blood pressure isn't always clear. It may be associated with the following:
- Hormonal problems, such as an underactive thyroid (hypothyroidism), overactive thyroid (hyperthyroidism), diabetes, or low blood sugar (hypoglycaemia)
- Over-the-counter medication
- Overdose of high blood pressure medication
- Heart failure
- Heart arrhythmias (abnormal heart rhythms)
- Widening, or dilation, of the blood vessels
- Heat exhaustion or heat stroke
- Liver disease
its simple in hot days when sweat comes out of the body it is the water present in blood capillaries ,so when the excess water is removed from the body the speed of the blood become slow due to slow speed blood pressure decreases and it result in low blood pressure.