It is also the most significant reversible cause for cardiovascular disease with numerous studies proving that the control of hypertension can lower the risk of cardiovascular events and mortality [6]. Screening and effective control of raised blood pressure has public health benefits and is cost-effective [7], and is therefore endorsed by the British National Institute for Health and Clinical Excellence (NICE) [8]. Both the guidelines and the data are limited to patients within certain age groups and it is unclear whether the benefits of treatment extend to the young [9], in whom prevalence is estimated to be between 5 and 20 % for those aged between 24 and 32 [10]. However, it is generally assumed that earlier treatment is associated with greater benefits in terms of longevity and life free from disease [2, 11].

Hypertension is often classed as “primary” or “secondary,” with the latter being due to some specific identifiable additional condition (see below). On the other hand the pathogenesis of primary hypertension is often multifactorial, although the diagnosis and complications are known to be associated with several risk factors such as race, family history, diabetes mellitus, obesity, inactive lifestyle, high sodium intake and excessive alcohol consumption [8, 12, 13]. Psychosocial factors and depressive illnesses may increase the risk of chronically raised blood pressure [14, 15]. Recent evidence also links severe vitamin D deficiency with the subsequent development of hypertension [16].

Although it is usually asymptomatic in its early stages, untreated chronic hypertension contributes to the early development of cardiovascular disease, renal impairment and disability, regardless of the aetiology. There is a 7 % incremental risk of mortality from ischaemic heart disease (and 10 % from stroke) for every 2 mmHg step in systolic blood pressure [17].Epidemiological studies suggest that a 10 mmHg lower systolic blood pressure (or 5 mmHg lower diastolic blood pressure) is associated with a 50 % reduction in the risk of death from coronary artery disease or stroke (Fig. 11.3) [17]. Hypertension therefore is an important condition to recognise and address even in young adults and both lifestyle modification and anti-hypertensive therapies to achieve blood pressure reduction are a priority to reduce risk. However, treatment goals should be individualised to take patient characteristics and co-morbidities into account. Recently, there has been limited evidence to suggest that excessive lowering of the diastolic blood pressure to below 70 mmHg in the high-risk elderly population with co-existing severe coronary artery disease or diabetes, may be associated with an increase in cardiovascular complications [6, 18–20].

John’s general practitioner (GP) arranged for him to have a series of blood tests (full blood count, urea/electrolytes, glucose, thyroid function tests and estimated glomerular filtration rate), urinalysis and electrocardiogram. She also arranged for 24-h blood pressure monitoring in order to confirm the diagnosis.

The use of ambulatory blood pressure monitoring (ABPM) is currently recommended by the NICE guidelines in order to confirm the diagnosis, when there are persistently elevated clinic blood pressure (BP) readings (between 140/90 and 180/110 mmHg) and an absence of end-organ damage (Fig. 11.4) [8]. Where ABPM is not available, home BP monitoring should be used since this shows a stronger correlation to daytime ABPM measurements than clinic BP readings [21, 22]. If clinic BP is the only available test, then this should be measured on at least three to six visits spanning a period of 3 months [23].

The following ABPM cut-offs have been recommended by both the seventh Joint National Committee and the European Societies of Hypertension and Cardiology guidelines to diagnose hypertension [24, 25]:

ABPM can also be used to monitor treatment response, and to clarify the diagnosis of [26]:

Systolic blood pressure readings over 180 or diastolic blood pressure readings over 110 mmHg suggest severe hypertension. In the presence of hypertensive ophthalmic changes such as retinal haemorrhage, papilloedema or exudates, or symptoms indicative of phaeochromocytoma, such as headaches, palpitations, sweating and labile blood pressure [27], this is termed “malignant” or accelerated hypertension and requires urgent treatment (within 24 h). On the other hand, in asymptomatic patients with no evidence of acute end-organ damage, the short-term risk of severe hypertension is low and there is no proven benefit of rapid in-patient blood pressure reduction [28, 29].

Based on the ABPM results (overall average blood pressure 138/87; daytime average 142/94), John was given a diagnosis of hypertension. Initial examination, blood tests and urinalysis were normal, suggesting no end-organ damage had yet occurred, but given John’s young age, his GP performed a more focussed cardiovascular examination and requested some further blood tests to identify whether this could be secondary hypertension (serum calcium, parathyroid hormone, serum lipid profile, aldosterone:renin ratio).