Can Being Sick Cause Hypertension?
Yes, acute illness can temporarily elevate blood pressure through multiple physiological mechanisms, but this represents a transient stress response rather than true chronic hypertension.
Physiological Mechanisms of Illness-Related Blood Pressure Elevation
The body's response to acute illness involves activation of compensatory systems that directly raise blood pressure:
The renin-angiotensin system (RAS) is upregulated during acute illness to maintain adequate organ perfusion, which increases vasoconstriction and promotes sodium and water retention 1
Fever, inflammatory response, fluid status changes, and altered kidney function all influence blood pressure during acute illness, making elevated readings common at presentation 1
If the ACE/Ang II pathway increases without adequate compensatory ACE2/Ang-(1-7) activity, deleterious hypertension can occur, particularly in patients with pre-existing cardiovascular risk factors 1
Clinical Context: Illness vs. True Hypertension
It is critical to distinguish between stress-related blood pressure elevation and chronic hypertension:
Hypertension is fundamentally a nutritional-hygienic disease rooted in long-term caloric excess, chronic supraphysiological sodium intake, excessive alcohol consumption, and psychosocial stressors 1
The rate of blood pressure increase appears more important than absolute values in determining clinical significance 2
Patients presenting with substantially elevated BP who lack acute hypertension-mediated organ damage are not considered to have a hypertensive emergency 3
COVID-19 as a Specific Example
The SARS-CoV-2 pandemic provided clear evidence of illness-induced blood pressure changes:
Initial reports suggest blood pressure at presentation might be higher in patients who develop more severe COVID-19, independent of baseline hypertension 1
SARS-CoV-2 binding to ACE2 and subsequent downregulation may induce pulmonary RAS dysregulation, leading to increased circulating Ang II and unopposed vasoconstriction 1
Concurrent acute kidney injury and endothelial dysfunction can magnify blood pressure elevation through ACE/Ang II upregulation 1
Clinical Implications and Management Approach
When encountering elevated blood pressure in an acutely ill patient:
Complete diagnostic evaluation should include laboratory analysis (hemoglobin, platelet count, creatinine, electrolytes, LDH, haptoglobin) and fundoscopy to assess for true hypertensive emergency 2, 3
Symptoms such as headache, visual disturbances, neurological changes, or chest pain warrant immediate assessment for acute hypertension-mediated organ damage 2
For patients without acute target organ damage, avoid aggressive blood pressure reduction as this represents a physiological stress response that will resolve with treatment of the underlying illness 3
Multiple factors must be accounted for including fever, inflammatory response, fluid status, and kidney function before attributing elevated readings to chronic hypertension 1
Key Clinical Pitfall
Excessive or rapid BP reduction in the setting of acute illness can lead to organ underperfusion, cerebral infarction, and damage to myocardium and kidneys 2. The elevated blood pressure during illness often serves a protective role in maintaining organ perfusion during physiological stress. Treatment should focus on the underlying illness rather than aggressive antihypertensive therapy unless true hypertensive emergency with target organ damage is present 3.