Investigations

The search for a cause of hypertension should be more thorough in the young, severe hypertensive, and more restrained in older patients.

NICE recommends that in all people with hypertension, offer to:

• test urine
  • test for the presence of protein in the urine by sending a urine sample for estimation of the albumin:creatinine ratio and test for haematuria using a reagent strip
• measure plasma glucose, electrolytes, creatinine, estimated glomerular filtration rate, serum total cholesterol and HDL cholesterol
• examine the fundi
  • for the presence of hypertensive retinopathy
• arrange for a 12-lead electrocardiograph should be undertaken (1)

Use of fasting blood samples will allow assessment of fasting glucose and assessment of triglyceride levels (1)

Further investigations should be guided by clinical suspicion of other factors such as heart failure or secondary causes of hypertension.

The American college of cardiology recommends the following basic and optional laboratory tests for primary hypertension:

• basic
  • fasting blood glucose (may include a comprehensive metabolic panel)
  • complete blood count
  • lipid profile
  • serum creatinine with estimated glomerular filtration rate
  • serum sodium, potassium, calcium
  • thyroid-stimulating hormone
  • urinalysis
  • electrocardiogram
• optional
  • echocardiogram
  • uric acid
  • urinary albumin to creatinine ratio (2)

NICE suggest that:

• if hypertension is not diagnosed but there is evidence of target organ damage such as left ventricular hypertrophy, albuminuria or proteinuria, consider carrying out investigations for alternative causes of the target organ damage (1)

Reference:

• (1) NICE (August 2019). Clinical management of primary hypertension in adults
• (2) Whelton PK et al. 2017 ACC/AHA/AAPA/ABC/ACPM/AGS/APhA/ASH/ASPC/NMA/PCNA Guideline for the Prevention, Detection, Evaluation, and Management of High Blood Pressure in Adults: Executive Summary: A Report of the American College of Cardiology/American Heart Association Task Force on Clinical Practice Guidelines. Circulation. 2018;138(17):e426-e483.