Diagnosis

Your doctor can often diagnose dehydration on the basis of physical signs and symptoms. If you're dehydrated, you're also likely to have low blood pressure, especially when moving from a lying to a standing position, a faster than normal heart rate and reduced blood flow to your extremities.

To help confirm the diagnosis and pinpoint the degree of dehydration, you may have other tests, such as:

• Blood tests. Blood samples may be used to check for a number of factors, such as the levels of your electrolytes — especially sodium and potassium — and how well your kidneys are working.
• Urinalysis. Tests done on your urine can help show whether you're dehydrated and to what degree. They also can check for signs of a bladder infection.