Thank you for the query. As per the history, your daughter is 25 yrs with symptoms of palpitation, Chest pain, dizziness and headache. Her BMI is approximately 24 kg/m2. First to answer your query, these symptoms can occur in severe dehydration, but the important question is why will your daughter have dehydration in the first place. In this context I would like to ask whether she had any recent episodes of severe diarrhoea or vomiting, and whether her daily fluid intake is sufficient or not. I would also like to enquire whether she has excessive urination, whether her menstrual cycle is normal or not and if there is any family history of cardiac ailments. There are hardly any blood tests which can point towards dehydration except for serum sodium (which is increased) and in some cases serum osmolality. Clinically her skin and tongue would be dry and her pulse volume will be feeble. Another easy method to check for dehydration is postural hypotension (first check her blood pressure in the lying down position, then make her stand and check her BP after 2-3 minutes, a fall in Systolic BP of 20mm of Hg and Diastolic BP of 10 mm of Hg or more, is positive). I would recommend certain investigations in her case - serum Hemoglobin (since anemia can often present with palpitation and dizziness), a thyroid profile and blood sugar screening (which can cause dizziness). A 12 lead ECG is suggested (since she has symptoms of palpitation and chest pain), to rule out any underlying cardiac ailment. In the meantime I would advise her to have sufficient fluid intake, a nutritious diet and to avoid any strenuous exercise. In case the investigations have any abnormality, you need to visit your primary physician for a thorough check up and a management plan. Hope this helps you out.