A Brief Synopsis of AFP's "Diagnosis of Secondary Hypertension: An Age-Based Approach"

A brief synopsis of : Diagnosis of Secondary Hypertension: An Age-Based Approach, ANTHONY J. VIERA, MD, MPH, and DANA M. NEUTZE, MD, PhD, University of North Carolina at Chapel Hill School of Medicine, Chapel Hill, North Carolina

Am Fam Physician. 2010 Dec 15;82(12):1471-1478. 

http://www.aafp.org/afp/2010/1215/p1471.html

     Hypertension is one of the most common illnesses seen today. It is a predictor of serious illness, which is why blood pressure is considered a "vital sign". Oftentimes, a cause can not be found, so the patient is given anti-hypertensive pills and sent on their way. Up to 10% of these patients have secondary hypertension, which can be corrected without anti-hypertensive medications. Depending on the age of the patient, different etiologies are more common than others for secondary hypertension. 
     First, when a patient presents with elevated blood pressure, it needs to be check two other times during two other occasions. Correct positioning of the cuff, cuff size, diet, and a full medication review should be performed to avoid chasing any zebras.  Common medications that can cause elevated hypertension are OCP's, steroids  diet pills, amphetamines  lithium, TCA's, decongestants, and several herbs, like ma huang and ginseng.  If the patient is a child, the onset of hypertension was rapid, or the history simply does not seem typical, investigating other causes of hypertension should be considered.
     Patients under 18 years old may have secondary hypertension from renal parenchymal disease or  coarctation of the aorta. Renal parenchymal disease includes glomerulonephritis, reflux nephropathy, and congenital abnormalities.  A BUN, creatinine, UA, urine culture, and renal ultrasound should be ordered. In aortic coarctation,  a murmur may be heard, or there may be a pressure difference between bilateral brachial, or brachial and femoral pulses.  Rib notching may be seen on x ray. MRI or transthoracic echocardiology can be done to rule out coarctation. 
     In patients between the ages of 19 to 39, common causes of secondary hypertension are renal artery stenosis, and thyroid dysfunction. In this age group, the renal artery stenosis is due to decreased renal perfusion from fibromuscular dysplasia   A high pitched, holosystolic, renal bruit may be heard. MRI with gadolinium, CT angiography, or doppler ultrasound can be used to diagnose this.  HypOthyroidism can cause an elevation in diastolic pressure. HypERthyroidism can raise systolic pressures. TSH can be tested in this age group, as well as any older subgroup.
     Patients between the ages of 40 to 64 may have elevated pressure from aldosteronism, obstructive sleep apnea, pheochromocytoma, or cushing syndrome. Patients with elevated aldosterone syndromes may have hypokalemia. The best test is to check morning aldosterone/renin levels. These patients may need to be referred for confirmatory testing.  In obstructive sleep apnea, a polysomnography or a clinical assessment tool with nighttime pulse oximetry may be positive. Pheochromocytoma patients will have the 6 P's (Pounding headaches, Palpitations, Palor, Panic, Pressue/Paroxysmal burst, and Perspiration) as well as the "rule of 10's (10% familial, 10% bilateral, 10% malignant, 10% calcify, 10% extramedullary). 24-hour urinary metanephrines or plasma free metanephrines should be checked. Cushing disease patients will present with a buffalo hump, central obesity, moon facies and stria, but I would bet that your cushing patient won't have any of these classic signs (unless your patient is a medical textbook model...) Tests to rule out this disease include a 24-hour urinary free cortisol, low-dose dexamethasone suppression test or late-night salivary cortisol test.
    In patients older than 65 years old with secondary hypertension, the most common causes are renal artery stenosis or renal failure.   Patients who develop hypertension late in life, those with atherosclerosis, or rapid deterioration of renal function when started on ACEI's or ARB's may have secondary hypertension. They can be imaged by MRi with gadolidium or CT angiography. Patients with suspected renal failure should get an ultrasound, GFR, and a UA with albumin level.