Diagnosis
The diagnosis of hypertension is by definition made by three separate measurements at least one week apart. Two caveats to this criteria is it must be in the presence mild elevations and in the absence of end organ damage. If either are not met, the diagnosis may be made without repeat measurements in some cases.
Obtaining reliable blood pressure measurements relies on following several rules and being cognizant of the many factors that influence blood pressure reading.
For instance, measurements should be at least 1 hour after caffeine, 30 minutes after smoking and without any stress. Cuff size is also important. The bladder should encircle and cover two-thirds of the length of the arm. The patient should be sitting for a minimum of five minutes. The patient should not be on any adrenergic stimulants, such as those found in many cold medications.
When taking manual measurements, the person taking the measurement should be careful to inflate the cuff at least 30 mmHg greater than systolic pressure. A stethoscope should be placed lightly over the brachial artery. The arm should be at the level of the heart and the cuff should be deflated at a rate of 2 to 3 mmHg/s. Systolic pressure is the pressure reading at the onset of sounds. Diastolic pressure is then defined as the pressure at which the sounds disappear. Two measurements should be made at least 5 minutes apart and if there is a discrepancy of more than 5 mmHg, a third reading should be done. The readings should then be averaged. An initial measurement should include both arms. Also, in elderly patients, it is recommended to measure pressures in multiple postures as they are at risk for orthostatic hypotension.
Once the diagnosis of hypertension has been made it is important to attempt to identify reversible (secondary) causes. In the adult population over 90% of all hypertension has no known cause and is therefore called "essential/primary hypertension". Often, it is part of the metabolic "syndrome X" in patients with insulin resistance: it occurs in combination with diabetes mellitus (type 2), combined hyperlipidemia and central obesity. However, in the pediatric population the opposite is true, most cases have a secondary cause and these should be pursued more aggresively.
Important causes of secondary hypertension are:
Heavy alcohol use
Renal artery stenosis
Obstructive sleep apnea
Pheochromocytoma
Hyperaldosteronism (Conn's syndrome)
Cushing's disease
Steroid use
Coarcation of the aorta
Chronic renal failure
Scleroderma renal crisis
Hyperparathyroidism
Liquorice (when consumed in excessive amounts)
Blood tests commonly performed in a newly diagnosed hypertension patient are:
Creatinine (renal function)
Electrolytes (sodium, potassium)
Glucose (to identify diabetes mellitus)
Cholesterol
Source: Wikipedia
|
