Hypertension is a widespread medical condition where the force of blood against artery walls is consistently too high. This sustained elevation can damage arteries and hinder proper blood circulation throughout the body. Hypertension is broadly categorized into two main types: primary and secondary. Primary hypertension, also called essential hypertension, accounts for the vast majority of cases and develops gradually over many years without an identifiable cause. Secondary hypertension, in contrast, results from an underlying, identifiable medical condition or specific factors, such as kidney disease, hormonal imbalances, or certain medications. Identifying the root cause of secondary hypertension is important, as treating the underlying condition can often lead to improved blood pressure control or even a cure.
Why Investigate Secondary Hypertension?
Investigating secondary hypertension is important because, unlike primary hypertension, it frequently has a treatable or curable underlying cause. Identifying and addressing this cause can lead to more effective blood pressure control, potentially reducing or eliminating the need for antihypertensive drugs. For example, treating conditions like renal artery stenosis or primary aldosteronism can often normalize blood pressure or significantly improve its management.
Targeted treatment of the underlying condition can also prevent long-term complications associated with high blood pressure, such as heart disease, stroke, and kidney damage. Early detection and intervention can minimize irreversible changes in blood vessels and organs. Recognizing the specific cause allows healthcare providers to implement more effective strategies, leading to better overall health outcomes for the patient.
When a Workup is Recommended
A healthcare provider may recommend a workup for secondary hypertension when certain patterns of high blood pressure emerge. These indicators often suggest an underlying cause rather than typical primary hypertension. One such clue is the onset of hypertension at a very young or older age, especially if there is no family history of the condition.
A sudden onset of high blood pressure or a significant worsening of previously controlled blood pressure can also raise suspicion. Hypertension that remains high despite treatment with three or more different antihypertensive medications, including a diuretic, is termed resistant hypertension and often prompts further investigation. The presence of specific symptoms like unexplained muscle weakness, frequent headaches, excessive sweating, or episodes of palpitations and dizziness might also indicate an underlying cause such as a hormonal imbalance.
Components of the Workup Process
The process of investigating secondary hypertension begins with a thorough initial assessment. This involves taking a detailed medical history, including family history of hypertension or related conditions, current medication use (prescription, over-the-counter, and supplements), and lifestyle factors such as diet, exercise, and smoking habits. A comprehensive physical examination is also performed to look for any physical signs that might point to an underlying cause, such as specific body habitus, abdominal bruits, or signs of organ damage.
Following the initial assessment, general laboratory tests screen for common underlying issues. These tests include a basic metabolic panel to check serum sodium, potassium, and creatinine levels, which help in assessing kidney function and electrolyte balance. A dipstick urinalysis also screens for proteinuria or hematuria, which can indicate kidney damage. Thyroid function tests, such as a sensitive thyroid-stimulating hormone (TSH) level, are included to rule out thyroid disorders as a cause of hypertension.
Based on these findings, more specific tests may be ordered if a particular cause is suspected.
Kidney-Related Causes
For kidney-related causes, such as renal artery stenosis, imaging like a renal ultrasound with Doppler or CT angiography may be performed to visualize blood flow to the kidneys.
Hormonal Causes
Tests for hormonal causes often involve specialized blood or urine tests. For instance, the aldosterone-to-renin ratio is measured for primary aldosteronism, and 24-hour urinary metanephrines or plasma free metanephrines are used to screen for pheochromocytoma. For Cushing’s syndrome, an overnight dexamethasone suppression test or 24-hour urinary free cortisol may be used.
Vascular Causes
If vascular causes like coarctation of the aorta are suspected, a chest X-ray and echocardiogram might be performed.
Sleep-Related Causes
For sleep-related causes like obstructive sleep apnea, a sleep study, such as a polysomnography, is often recommended to monitor breathing patterns and oxygen levels during sleep.
Implications of a Diagnosis
Once a specific secondary cause of hypertension is identified, the implications for patient management are clear. Finding the underlying condition allows for targeted treatment, an advantage over primary hypertension. This focused approach can lead to better control of blood pressure, and in some cases, it may even result in a complete resolution of hypertension, reducing or eliminating the need for blood pressure medications.
Even if blood pressure does not fully normalize, treating the root cause often leads to substantial improvement, making hypertension much more manageable. This can significantly lower the risk of long-term complications like heart attacks, strokes, and kidney failure. Ongoing management and regular follow-up with a healthcare provider remain important to monitor blood pressure, adjust treatments as needed, and ensure the underlying condition remains controlled.