Diagnosing hypertension
Hypertension is defined as a blood pressure >140/90 mm Hg, the average of ≥2 properly measured readings at ≥2 visits in a medical setting.15 The proper equipment, including a well-fitting blood pressure cuff, and technique to measure blood pressure are essential to avoid misdiagnosis. The patient should be at rest for ≥5 minutes, without active pain or emotional distress.
Most cases of hypertension (90% to 95%) are primary, commonly called essential hypertension. However, the differential diagnosis also should consider secondary causes, which may include:
- obesity
- medications
- chronic alcohol use
- methamphetamine or cocaine use
- primary kidney disease
- atherosclerotic renal artery stenosis
- obstructive sleep apnea
- hypothyroidism
- primary hyperaldosteronism
- narrowing of the aorta
- Cushing syndrome
- primary hyperparathyroidism
- polycythemia
- pheochromocytoma.
Medical evaluation. Once the diagnosis of hypertension is made, a medical evaluation is indicated to determine if the patient has end-organ damage from the elevated pressures, such as renal disease or heart disease, to identify other modifiable cardiovascular risk factors, such as hyperlipidemia, and to screen for secondary causes of hypertension. This evaluation includes15:
- a physical exam
- review of medications
- lipid profile
- urinalysis to screen for proteinuria
- serum electrolytes and creatinine
- electrocardiogram to screen for left ventricular hypertrophy or prior infarction
- fasting glucose or hemoglobin A1c to screen for type 2 diabetes mellitus.
Psychotropic drugs. In psychiatric patients, the evaluation must consider the potential impact psychotropic drug effects and drug–drug interactions can have on blood pressure (Table 2). For example, patients taking both diuretics and lithium are at increased risk for dehydration and increased serum lithium levels, which could cause severe neurologic symptoms and renal insufficiency.16 Several antihypertensives when taken with venlafaxine can increase blood pressure, but antihypertensives with α-1 blocking psychotropics can decrease blood pressure. Monoamine oxidase inhibitors can cause hypotension or hypertension with various classes of antihypertensives. Stimulants, such as methylphenidate, atomoxetine, dextroamphetamine, armodafinil, or modafinil, alone or combined with antihypertensives, can cause hypertension.17
Substance abuse, particularly alcohol, methamphetamine, and cocaine, can cause difficulty controlling blood pressure. Patients with refractory hypertension should have a reassessment of substance abuse as a potential cause.