Approach in clerking hypertension
More than 90% of all cases of hypertension are primary or idiopathic or essential. Hence the main aims of clerking hypertension are:
- To identify symptoms suggestive of a secondary cause
- To establish concomitant risk factors for cardiovascular disease
- To seek any symptoms suggestive of target organ damage.
There are often no symptoms or signs at presentation, except for the few times when patients may present with headaches, nosebleeds, visual symptoms, or neurological symptoms.
A full examination (including height and weight) is however usually recommended, to detect any signs of an underlying condition or target organ damage.
Baseline screening tests are useful in all patients to check for complications. Specific tests may only be logical if there is a high suspicion of an underlying secondary cause.
Blood pressure measurement
This is needed to confirm a diagnosis of hypertension. An average of two correctly checked blood pressure readings, at least 5 minutes apart is recommended.
Identification of a secondary cause
Features suggestive of secondary hypertension include:
- Young patient (<40 years)
- Rapid onset of hypertension
- Sudden change in blood pressure readings when previously well controlled on a particular therapy
- Resistant hypertension that is unresponsive to pharmacological therapies.
If a secondary cause is suspected, then the presence of specific symptoms may suggest a particular cause and guide further investigations:
- Flash pulmonary oedema or widespread atherosclerosis: renal artery stenosis
- Poor feeding in children, or cold legs: aortic coarctation
- Swelling and hypertension in a pregnant patient: pre-eclampsia
- Oedema and foamy urine in a non-pregnant patient: nephrotic syndrome
- Renal impairment, prostatic enlargement, previous urethral instrumentation, or renal calculi: obstructive uropathy or CKD
- A family history of polycystic kidney disease, intracranial aneurysms, or subarachnoid haemorrhage in a young patient: polycystic kidney disease
- Episodic symptoms consistent with a hyper-adrenergic state, such as panic attacks, sweating, palpitations, and abdominal cramps: phaeochromocytoma
- Headaches, nocturia, and paraesthesiae (symptoms of low potassium), may point to hyperaldosteronism. Majority are however normokalaemic
- Depression, weight gain, hirsutism, easy bruising, and low libido: Cushing’s syndrome
- Heat intolerance, sweating, palpitations, and weight loss: hyperthyroidism
- Bone pain, paraesthesiae, and myalgia: hyperparathyroidism
- Excessive daytime sleepiness in an obese patient, +/- loud snoring, erectile dysfunction and restless sleep: obstructive sleep apnoea
- Use of oral contraceptive pills or NSAIDs, or chronic alcohol excess: toxic cause.
Physical findings suggestive of a secondary cause include the following:
- Renal bruits: renal artery stenosis
- Enlarged kidneys +/- hepatomegaly or a hernia: polycystic kidney disease
- Arteriovenous fistulae (for haemodialysis): end-stage kidney disease
- Flank tenderness or prostatic enlargement: obstructive uropathy
- Facial or limb oedema and proteinuria in a pregnant patient: pre-eclampsia.
- Oedema in a non-pregnant patient: nephrotic syndrome.
- Radio-femoral delay and a disparity in blood pressure readings between the arms along with systolic or continuous cardiac murmurs and weak or impalpable distal pulses: coarctation of the aorta
- Moon face, thin arms and legs, truncal obesity, striae, and skin thinning: Cushing’s syndrome
- Isolated eyelid oedema with dry skin and a thick tongue: hypothyroidism
- Exophthalmos, proptosis, and lid lag: hyperthyroidism
- The deposition of calcium just inside the iris, or palpation of jaw tumours: hyperparathyroidism
- Obesity, maxillomandibular abnormalities, and macroglossia predispose to obstructive sleep apnoea, and there may be sweating in paediatric patients
- Signs of chronic alcohol excess, such as jaundice, hepatomegaly, spider nevi, ascites, and general neglect of appearance.
Concomitant cardiovascular risk factors
- Smoking: active or passive; type of cigarette or tobacco, quantity, and duration of habit.
- Diabetes mellitus
- Known ischaemic heart disease or previous myocardial infarction.
- Previous stroke or transient ischaemic attack.
- Elevation of cholesterol or triglycerides.
Target organ damage
- Cardiovascular disease
- Cardiac failure: dyspnoea, limb oedema, PND, and orthopnoea.
- Cardiac murmurs, thrills, or heaves.
- Left ventricular hypertrophy.
- Cerebrovascular disease
- Speech difficulties, visual disturbance, transient focal neurology, or other symptoms suggestive of a TIA or stroke should be obtained.
- Carotid bruits: carotid artery stenosis
- Residual functional loss after a stroke.
- Renal failure
- May be asymptomatic
- Decreased or increased frequency of urination
- Pruritus, lethargy, and weight loss
- Often asymptomatic, but may present with visual loss or headaches.
- Hypertensive retinopathy on fundoscopy
Baseline screening tests
- ECG for signs of previous MI or left ventricular hypertrophy.
- Chest x-ray for evidence of cardiomegaly, widening of the left subclavian border, and the ‘M’ sign and rib notching for coarctation of the aorta.
- Serum electrolytes, urea, and creatinine, with random blood sugar and serum cholesterol. If diabetes is suspected, a fasting blood sugar test is required.
- Urine dipstick test for glycosuria and proteinuria.
- Blood tests
- Plasma renin and aldosterone levels: hyperaldosteronism
- Plasma renin activity to screen for renal artery stenosis. A renal angiogram is the most specific and sensitive test.
- Late-night salivary cortisol: Cushing’s disease. Confirmation is with the overnight dexamethasone suppression test.
- LFTs to screen for suspected chronic alcohol excess and liver dysfunction.
- TFTs to screen for suspected hyper- or hypothyroidism.
- Serum calcium levels for possible hyperparathyroidism.
- Urine tests
- 24-hour urine collection for measuring catecholamines to exclude phaeochromocytoma or to measure protein levels in suspected pre-eclampsia or nephrotic syndrome.
- Ultrasound of kidneys and adrenal glands:
- A unilateral small kidney (chronic pyelonephritis or renal artery stenosis)
- Bilateral shrunken kidneys (with chronic renal failure)
- Hydronephrosis (obstructive uropathy)
- CT pyelogram (for strongly suspected renal calculi)
- Polycystic kidneys
- CT or MRI of adrenals for suspected phaeochromocytoma
- MRI: to investigate renal artery stenosis if a renal angiogram is contra-indicated.
- Ultrasound of kidneys and adrenal glands:
Renal biopsy: to detect the underlying cause of nephrotic syndrome in adults and rarely in children.