Decoding Secondary Hypertension: Unveiling Common and Dangerous Causes
Let's delve into the complexities of secondary hypertension. I'll walk you through the most frequent cause and highlight one of the most critical yet often overlooked reasons. And stay tuned, as I'll share a fantastic resource that's now freely available for all NHS staff.
https://bestpractice.bmj.com/info/bma - Register here for FREE.
Navigating secondary hypertension isn't a walk in the park. Unlike the structured guidelines we adore, there isn't a comprehensive pathway for this condition in general practice. However, many areas have specialized clinics for suspected cases.
Criteria for Referral in Secondary Hypertension:
Four key reasons might prompt you to suspect secondary hypertension:
Patient under 40 years old.
Uncontrolled on four medications.
Previously controlled but now uncontrolled despite ruling out compliance issues.
Recognizable characteristics of secondary hypertension conditions.
Let's dive into two significant causes:
1. Conn Syndrome - Primary Hyperaldosteronism:
5% of hypertensive patients are thought to have this condition. There is just too much aldosterone, which causes sodium reabsorption in the kidneys, in exchange for potassium – which is then excreted in the urine. And so, exam question here, Conn’s Syndrome is sometimes, but not always, associated with hypokalaemia. Low K+. And whilst we are taking about urinary excretion, another common symptom is nocturia and/or polyuria. Primary hyperaldosteronism can run in families and can sometimes be caused by an aldosterone producing adenoma or with bilateral adrenal hyperplasia. This subtype can respond to surgery so it’s pretty important to pick up.
In terms of Ix/tests –1st all hypertensive patients will have U+Es, so look at the potassium and you can do an aldosterone/renin ratio if you are not referring.
2. Pheochromocytoma - The Dangerous Cause:
There is a classic triad of symptoms associated with pheochromocytoma that you need to remember:
1. Diaphoresis – excessive sweating
2. Palpitations
3. Headaches
These symptoms can come and go in paroxysms but do get progressively worse with time. Patients can also look very pale when the attacks come on. It’s caused by a catecholamine excreting tumour most commonly in the adrenal gland. And surgery is curative in the majority of cases. Although rare, it does run in families – up to 40% of cases are familial.
In terms of Ix/Tests: if you feel there is a low probability, so only some symptoms, you could consider doing a 24-hour urinary measurement of catecholamines. This test is useful because of its high specificity - and specificity is a test’s ability to accurately rule out a condition
But if there is a strong suspicion and you are not admitted directly, I would probably refer.
Bonus: Resource Unveiling
An invaluable resource, BMJ Best Practice, is now free for all NHS staff. It offers detailed insights into conditions, providing a secondary care slant beneficial for deeper understanding and learning.
To access this resource, check your CCG newsletter or find it under 'Primary Care Training and Development.' https://bestpractice.bmj.com/info/bma - Register here for FREE.
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